power quest an enthusiasts perspective

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Power Quest – An Enthusiasts’ Perspective* on the MK-III MR2 Introduction.............................................. 2 Stock Power Limits........................................3 Research.................................................. 6 Boosted ,Blown or Sprayed – Turbo, Super Charger or Nitrous? .......................................................... 7 New Engine Street Break-In Procedure......................8 Boosted 1Z Engine Tuning Summary..........................9 Dynos, Shops and Tuners..................................10 Aftermarket CAMS.........................................14 Stock ZZ Engine Cam specs..................................................................................... 15 CROWER Cam comparison to 1Z............................................................................ 15 Fuel and Ignition Upgrades...............................16 Toyota Coil On Plug Ignition.................................................................................. 17 Known Ignition issues............................................................................................. 18 Cooling System Upgrades..................................18 Oiling System Upgrades...................................19 Crank Case Ventilation...................................21 Power Supporting Modifications...........................22 Emissions Testing........................................24 OBDI ready flags and two-trip logic...................24 Stock Sensor Info........................................25 O2 volts and relative Air Fuel Ratios...................................................................... 26 Mass Air Flow Sensor............................................................................................... 27 Stock ECU Facts..........................................29 Bill Sherman Page 1 6/6/2022 My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Page 1: Power Quest an Enthusiasts Perspective

Power Quest – An Enthusiasts’ Perspective* on the MK-III MR2

Introduction........................................................................................................................2

Stock Power Limits............................................................................................................3

Research..............................................................................................................................6

Boosted ,Blown or Sprayed – Turbo, Super Charger or Nitrous?................................7

New Engine Street Break-In Procedure..........................................................................8

Boosted 1Z Engine Tuning Summary..............................................................................9

Dynos, Shops and Tuners................................................................................................10

Aftermarket CAMS.........................................................................................................14

Stock ZZ Engine Cam specs...........................................................................................15

CROWER Cam comparison to 1Z.................................................................................15

Fuel and Ignition Upgrades............................................................................................16

Toyota Coil On Plug Ignition........................................................................................17

Known Ignition issues....................................................................................................18

Cooling System Upgrades...............................................................................................18

Oiling System Upgrades..................................................................................................19

Crank Case Ventilation...................................................................................................21

Power Supporting Modifications....................................................................................22

Emissions Testing.............................................................................................................24

OBDI ready flags and two-trip logic.........................................................................24

Stock Sensor Info.............................................................................................................25

O2 volts and relative Air Fuel Ratios............................................................................26

Mass Air Flow Sensor....................................................................................................27

Stock ECU Facts..............................................................................................................29

Throttle Position Values............................................................................................29FAIL-SAFE MODE...................................................................................................29

Revision History...............................................................................................................30

The term crank horsepower (CHP) is used deliberately to indicate an estimated value. When an actual HP value is known or expected wheel horsepower(WHP) is used.

Bill Sherman Page 1 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Introduction

In the early days of Spyderchat, when someone said, “My MR2 is slower than a Honda Prelude …” a common response was “Drag racing’s for pussies! Are you a pussy?”

Fortunately, the board has mellowed and such posts are now answered in more tempered fashion with “You can’t handle what little ya got!” and “Learn to drive Fanboy!”.

When it comes to power, no matter how much you have, there’s always gonna be some guy making more with better reliability for less money all while looking better doing it. Or he’s kicking your butt with less!

It may seem obvious but the only real limitation to making power is motivation.Doesn’t matter what’s lacking be it knowledge, time, money, a garage, tools or talent.If any of these are preventing you from doing anything then your just not motivated enough to get ‘er dun!

There, isn’t that nicer than saying “S E A R C H …..ya Noob!!” It’s about as useful.

In the quest for power, an engine swap is a natural first thought. Many successful N.A. swaps have been performed. In terms of skill and cost they range from the reasonable Toyota 2ZZ-GE, to the not so reasonable 3MZ-FE to the totally foreign hp Honda K20.

Both ZZ engines have strengths and weaknesses, clues to which can be found in these papers: Development of the 1Z-FE & Development of the 2Z-GE and 2ZZ MMC Liners

Like most contemporary 4-cylinder’s, they both respond reliably and well to mild levels of F.I. The 4-valve-per-cylinder, pent-roof heads with their centered plugs and tapered squish are detonation resistant despite having factory compression ratios of 10:1 and 11.5:1 respectively.

The main focus of this thread is forced induction in a 1Z powered street car because chances are your MR2 already has one and F.I. is the method of choice because N.A. mods will never break 180whp for less than $10k. A 2Z swap revved to 10,000rpm might hit 225whp. Someday…There IS a point somewhere above 350whp where swapping in a force-fed 2Z makes more sense though. This 2Z Build thread compares and contrasts 1Z and 2Z engines.

Tracked cars have their own requirements & restrictions dependent on class and venue and will barely be mentioned in this document again.

Bill Sherman Page 2 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Stock Power Limits Some Typical 1Z Power Results

Unlike the MK-I and MK-II models from the ‘80’s and ‘90’s, the MK-III never had a factory F.I option. Except for a sensor-failure induced safe-mode and fuel-cut rev-limiter, there are no factory ECU safeguards (MAP sensor) to limit power production. A ZZ engine’s ECU will allow power to build until something lets go.

That may sound great but, unlike the older 3S-GTE, there’s not as much strength in the rotating assembly so a 1Z will not reliably make 300Chp on the stock bottom end for long. There are other challenges as well, including a returnless “deadhead” fuel rail, hi-impedance, pencil-style injectors, three 02 sensors and an unhackable OBDII ECU. The 5-volt hotwire MAF still makes for good driveability under mild boost but becomes a constraint later on.

Although both are an open deck design, there have been no reported instances of core shift. A few extreme buildups have fitted custom bore guards in both 1Z and 2Z blocks.

The 1Z has cast pistons in a 79.00mm bore with grey steel cylinder liners. Aftermarket piston makers can create any dimension and CR within reason but 8.8:1 in a 79.50mm diameter are frequently used. Up to 350Chp, a .50 mm overbore on stock bore liners that retains the OEM MLS head gasket has worked well.

Sleeving the 1Z is overkill for anything under 300Chp and possible even up to 400Chp. There have been HG sealing issues with 2.0 liter 1Z's overbored to 82mm.

The 2Z has Metal Matrix Composite (MMC) liners that CANNOT be machined. Finding forged pistons that fit is a trial and error process on a used block. Sleeving may be the only reliable option but the 5.5mm distance between bore walls is already 3.0mm closer than on the 1Z thus making cross-bore heat transfer an issue.

Stock ZZ cranks have been proven by MWR to be good to over 600Chp.

Stock 1Z rods tend to pretzel just over 300Chp on a decent tune, much sooner with detonation. Carver takes one for the team! then Morris bends a stock rod at 291whpCrank/rod bearings also tend to flatten out north of 300Chp.

The 68mm 1Z throttle body tapers to 55mm and reportedly flows 400CFM capable of supporting up to 270Chp naturally aspirated. When force-fed, the TB and intake manifolds are good to at least 450Chp in the 1Z and over 600Chp in the 2Z.

The stock clutch will hold 175-190Chp for awhile as long as its not launched hard.There have been several failures of 5sp and 6sp transaxles at stock power levels. Failure points are input/output bearings, the 1,2 synchro and 3rd gear. The bearings were reportedly changed in ’03+, use a GL-4 gear oil for the synchro and LSD for strength. Avoid GL-5 rated gear oils.

Bill Sherman Page 3 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Swapping a 6MT into a 1Z Spyder The SMT has a different throttle body

Stock Limitations on Fuel and Air Flow Toyota Fuel Injection Explained

The fuel pump runs at 44-50 psi supporting about 280Chp. However, the 24lb/252cc injectors can only support 180-190Chp at 45psi and 9x% duty-cycle.

Depending on the setup, the MAF signal when in a 66mm stock I.D. sampling tube needs to be re-scaled starting at either ~10psi of boost or ~280Chp whichever comes first. After that, part-throttle drive-ability begins to deteriorate until, around 330Chp, the car drives like a light switch. Meaning, it only drives well under two conditions: light throttle cruise or full WOT. Anything in-between bucks and bogs from too much fuel.

Putting the stock MAF in a 76mm diameter tube doesnt solve the problem entirely but does move it up the power band. How far up? IDK.

Clamping the MAF volts at 4.9v and using a 3-bar MAP sensor resolves this but the MAP module in the EM-blue doesnt compensate for the weather and the PFC for the 1Z doesn’t support a MAP sensor.

The WRX Sti or Turbo Supra MAFS reportedly get past all this but scaling one to work can be time consuming and requires a standalone EMS.

Bottom Line - what these limits really mean.

The most cost effective power upgrade is an internally stock 1Z running 5-7psi of boost. Available in kit form starting at $3000.00 they add 80-100hp at $30/HP.

With the right supporting mods. an internally stock 1Z streetcar can put down 225-250whp with no lag, stock fuel economy, excellent off boost driveability and OBDII compatibility all while delivering reliability measured in years and 10’s of thousands of miles.

1Z Weak points: pre-cats, rods and transaxles.

A stock 2Z is trickier to tune but can reach 275-325whp at just under 1-bar due to a better head, VVTI-L, higher rpm, 11.5:1 CR, oil squirters and beefy-beefy connecting rods.

2Z Weak points: pistons, lift bolts and transaxles.

From Left to Right - 2Z, Crower and 1Z rods

Do not boost a sick engine! How to do a compression check

Bill Sherman Page 4 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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If your motivated enough to address the respective weak points then 300-500whp is within reach.

Bill Sherman Page 5 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Research

A Built Turbo Engine Swap is challenging enough when well informed and entertaining to others when your not because… 

1. They require time, space, expense, sacrifice and the indulgence of family. Sometimes a lot of each.

2. Trusting it all to a shop may lead to dashed expectations but doing too much of the work yourself can too☺

3. A good local tuner whose familiar with your EMS may not exist and tuning it yourself might be worse than ever starting the project in the first place☺

4. The cylinder ring-seating period of the break-in period is very brief. The break-in tune isn’t the same as the daily driven or maximum effort tune. Don’t get caught with a brand new engine and an untuned ECU with an empty or unknown map. You can’t break it in from a scratch tune and you can’t create a scratch tune in time to break it in.

Here’s some light reading!

Building a 1Z discussion Informative tales of various Build Threads

Morris Uses A GT28R to force 20psi down a 1Z

TurboJimbo hits a stock 1Z with the GT2871R

1Z Turbokits and Dyno MWR 1Z Turbo Kit and Dynos

MWR Turbo 2Z Thread with Dyno charts MWR drag 2Z puts down 666whp

Turbo Corolla Parts list

A 1Z Turbo kit with a Factory Warranty

Garrett GT-series Turbochargers

Generic Turbo Terms and Definitions

Bill Sherman Page 6 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Boosted ,Blown or Sprayed – Turbo, Super Charger or Nitrous?

Superchargers don’t make power the same way turbochargers do therefore a S/C car feels and behaves differently.

Some argue a supercharger is more in keeping with the lightweight spirit of the MR2 Spyder. A debate Thread...

Some basic differences include:

Changing the pulley and the s-belt is the only way to change the boost on a S/C. This can be a good thing for the tuning challenged who wouldn’t be able to resist the temptation of a boost controller knob.

Given two identical cars with identical WHP, the turbo’d one will be less stressed than the S/C version. 200whp takes 230Chp with a turbo and ~240 with a S/C.

A turbo conversion deletes most, if not all, N.A. I/H/E mods but a S/C will keep them including the stock intake and exhaust if the car still has those. However, an aftermarket header and exhaust should be swapped in because the stock setup is very restrictive and the main cat has been known to melt around 190whp. A turbo engine bay will run hotter than a S/C with similar IAT’s

A S/C may be easier to tune because boost is linear.

A turbo bay is easier to work in unless the firewall is cut to allow access to the S/C.

Some S/C Success stories

WEB 3.0 Rotrex project

CURT’s Rotrex SuperCharger

The CarverCharger Kit probably a dead project but who knows

USPSPRO's Rotrex puts down 242whp & SgtSpyder's custom MP45 build Nitrous on the ZZA few have tried but most shouldn’t have bothered. Weed thru the thread drift to see how Carver's 1Z did when squeezed & 2Z N20 Set up in post #4

Bill Sherman Page 7 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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New Engine Street Break-In Procedure

This can also be done on a loading dyno set to inertial mode or an inertial dyno.

The break-in period should either use the stock computer and stock injectors or a known good naturally aspirated calibration.

1. Fill crankcase with the cheapest 5w-30 DINO juice available.

2. Pull coils, plugs and EFI-1 fuse so injectors don’t fire, disconnect WG rod and oil return line at the pan.

3. Turn key to ACC/ON* and check for fuel leaks at the tank, rail, FPR etc…

4. Crank engine for 30-45 seconds making sure the turbo oil return line is draining.

5. Install stock-spec plugs such as Denso IK-16 if 1Z. Reinstall coils, EF-I fuse and reconnect oil return to pan.

6. Start engine and let idle up to 176* or until t-stat opens then shut it down.

7. R&R the oil and filter because it now contains assembly lube and some metal.

8. Let engine/bearings cool down for an hour.

9. Take her out and bring up to operating temp keeping RPM’s under ~3000.

10. Pull to 4k in 3RD at about 1/2 throttle then let off the gas and coast.

11. Let the RPM’s drop to ~1500 while coasting under vacuum.

12. Repeat steps 10 & 11 three more times then drain and replace oil.

13. Let engine/bearings cool overnight.

14. Drive for 500 miles before boosting or until the new clutch stops chattering, whichever comes later

15. Switch to full synthetic oil.

*If you have en Emanage, floor the pedal to open the throttle plate all the way!!!

Bill Sherman Page 8 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Boosted 1Z Engine Tuning Summary

Read Which EMS for built 1Z to run 300whp & E-manage Resource Thread

These EMS are known to work with the ZZ engines and transmissions.Piggy-Backs(1Z only) Greddy Emanage Blue&Ultimate, AEM FIC and UnichipStandalones(1Z or 2Z)Apexi PFC , HKS Fcon V Pro and Hydra Nemesis

The Apexi PFC is incompatible with the SMT and doesn’t pull timing in response to the knock sensor therefore a J&S Safeguard or Vampire is a good idea with this standalone. It also has no MAP sensor support. Read about Kevin Bean's Co-Pilot for the PFC

380cc,525cc and 630cc injectors are commonly used and idle well even with a piggy-back and the deadhead rail. 630’s can be challenging and are probably the largest that can be used without a standalone EMS even with a return system.

Any automotive gas engine will make good power over a fairly wide range of AFR's. Anywhere between 10 and 13:1. 00. A mildly boosted 1Z responds well when boosted AFR's are in the hi-11's to low 12's. Off-boost should be in the mid-to-high 14’s.

As soon as the engine enters boost, the A/F meter should drop to the desired level and STAY THERE. It shouldn’t dipsy-doodle all over the place. Pay close attention to throttle tip-in at various load points as lean spikes are common and must be tuned out.

The ideal AFR curve is the opposite of torque curve. Meaning it should be go richer just before, during and after peak torque. Therefore, on a 1Z, the idea is to be a .5pt richer between ~4200-4800 rpm. Fluctuations of a .25 pt or so are tolerable and unavoidable with a piggyback but a deviation of a .5pt or more between boost onset and redline is not acceptable

With the fueling set, power production is primarily a function of ignition timing, though cam timing (VVTi) can have a noticeable effect as well, if one has the means to adjust it.The exact amount of timing retard required is really dependent upon the individual setup (e.g. intercooling efficiency, octane rating, compression ratio, etc., etc.), but sometimes using roughly .75 degrees of ignition retard per 1 psi of boost can be a good starting point. Above all, keep this in mind. An engine will be less stressed and run much more efficiently with more timing and less boost…there is a point where it is counterintuitive to retard timing in order to continue raising boost.

In the 200-250crank range and using an A/A I/C without chemical intercooling, maximum total 1Z timing should be no more than mid-teens at 6500-7000rpm.If the rev-limit has been increased or CR reduced then more timing advance may be needed.

On a cold day (40F) you might get away with hi-teens but that’s iffy. The stock ECU

Bill Sherman Page 9 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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won’t retard timing or add fuel under boost. But it will pull timing in response to intake temperatures and/or Knock.

With methanol in a 50/50 mix, stock timing +2° is possible with total timing in the low-20’s This is true even when ambient is in the triple digits. But, just like a frat party, aggressiveness is seriously bad news when the alcohol runs out unexpectantly! 

EGT’s shouldn’t exceed 900F at idle or 1500F in 4th gear at WOT

Dynos, Shops and Tuners

My MR2 has been on three models of Mustang(250,500&1100), two DynoDynamics and a DynoJet 248x at 6 different shops comprising ~120 pulls. These consisted of two group dyno days, two tuning sessions and 3 solo power pulling sessions just to see where the car was at. The experiences, while mostly positive, make me skeptical of power claims, charts, operator competence and shop motives. There’s just too much voodoo involved.

Results for the same car obtained from different dyno's or even the same dyno on a different day can easily differ significantly in terms of area-under-the-curve and peak power. It can be worse when F.I is involved because discrepancies increase as power levels rise. For instance: The VE profile of a hi-boost 1Z will be completely different from stock or one that’s mildly force-fed.

Choosing a Shop for TuningWhere there’s a choice, pick one that has the most experience with your engine and EMS. Find out whatever you can about their reputation and time in business. Has it had the same owner and location or does it change/move around a lot? Ask if there’s a “dyno day” coming up and bring a truck or the Spyder it doesn’t matter. Just get a feel for what’s going on and stay clear of the rollers!

Dyno Type The loading units are better for tuning because they can hold a steady-state at any rpm and load point to dial in fuel and timing.. Whereas, an inertial unit is good for bragging rights because WOT runs will read the highest on them.

Don’t dismiss a shop simply because its “got a DynoJet”. Ask which model and options they have. For example: An “Eddy Current Brake module” is one of the Accessories for a DynoJet model 224x but isn’t available for the 248x model line. This module transforms the 224x into a loading dyno.

An additional issue with inertials and the Spyder is weight. The back of the car only weighs 1200lbs but the drum on a 248x weighs 3000lbs. This makes it difficult to simulate realistic street loads and has a tendency to create a tune that makes great power on the dyno but is too far advanced and too lean for the street!

Bill Sherman Page 10 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Dyno operatorExperience, competence and honesty. Remember, they can make the graph look any way they want. Never tell them how much you EXPECT to make. Otherwise, you might be presented with a chart showing tantalizingly less. This is the bait to sell tuning services.

Do yourself a favor by arriving at the shop with a 18mm x 1.5 WB bung already in place.If the wideband O2 bung is after the main cat then it will read at least a .5pt leaner and possibly leaner than that if there’s a strong tailwind blowing into the shop. This is where an unscrupulous operator can make some money by positioning the sniffer just inside the tailpipe where it will read dangerously lean. "DudE! We need to richen it up before we can go any further or your engines gonna blow!! More bait…

Correction factorsThese are used to adjust power levels for atmospherics back to a known reference point for repeatability and comparison purposes. It’s perfectly valid to apply them to a N.A. engine chart as long as you know which of a dozen possible ones were used.

They’re problematic with forced induction because the standard factors for altitude, barometric pressure and ambient temperature are seriously skewed by boost.

Ambient temperature is an important tuning value because it affects how much timing an engine will tolerate. But it’s not always a valid correction factor for a F.I engine due to the adiabatic nature of F.I. and the various intercooling countermeasures deployed to reduce IAT’s. Ambient temps are not what the engine is seeing.

Additionally, a shop could be trying to build a reputation as “being able to get more power” by telling its dyno ambient is always 120*F and applying a correction factor back to 60F*.Correction factors applied on F.I. power pulls are not useful and might indicate the operator is inexperienced or making an attempt to get artificially high numbers.I don’t like "graph smoothing" either because it can be used to hide an inadequate inductive RPM pickup and/or detonation. 

For instance, the pickup can initially be intentionally misplaced to represent knock, which appears as jagged lines on the power curve, this is more “bait" because the operator, by merely positioning the pickup correctly for a subsequent run, can point at the improvement and say “It was pinging pretty bad when you brought it in…”.

3rd vs. 4th gear power pulls 4th is the best to use because its almost a 1:1 ratio. The transmission isn’t adding any torque multipliers. 3rd is used because the RPM's max out sooner and at a lower load level. After several 3rd gear pulls, the shop can say they'll get you more power, when all they really do is surf the net for 1/2 an hour. The next pull will show an increase because they did it in 4th gear on a cooled down engine. Its still OK to use 3rd gear and dyno operators like them because they're less risky (less

Bill Sherman Page 11 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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engine load). It also gets you on & off the rollers sooner on "dynodays" when cars are lined up.  It may show a higher final HP value but the total power producing area under the curve will be smaller than a 4th gear pull simply because a 4th gear pull takes longer. When more work is done over a longer period of time it takes more power.

Be suspicion if a shop tries to sell services based on comparing two different gears.

Tire pressure and strapping downforce Both have a measurable effect unless it’s a hub dyno. How much? It all depends. It can be measurable.

Jinxing the Run ParametersEach dyno needs to be setup for each vehicle. The operator will enter various values such a weight, hp at 60mph (usually a value between 40 and 50hp) and top speed in tested gear (101mpg in 4th). And, that’s not all.

Practically every dyno has internal baseline calibration values that can be incorrect such as setting its installed elevation at 5280ft when its on the coast.. Like all machines, they also have tolerances, operating ranges. margins of error and parts that wear out.

Ask when was the last time they had the machine calibrated. You don’t have to pretend to understand. Your simply looking for a straight forward answer such as “I don’t know” or better yet, “Four times a year, last time was a month ago and here’s the signoff sheet we use” Of course, any checklist/certificate could be a fake.

Try asking the shop to measure how much WHP your making in 2nd gear at 2000rpm.

Dyno Charts are Crazy MakingWhen looking at a dyno chart, its best to look at the shape and location of the curves, what the run parameters were and the area under the curve. Peak values are what that particular car made on that particular dyno on that particular day. It’s no guarantee of what a similarly equipped vehicle might make.

WHP & WTQ are the only values that matter. Flywheel is always an inaccurate calculated estimate unless measured on an engine dyno. If you must calculate wheel power by backing out parasitic losses then multiply flywheel by .875% The MK-III takes much, much longer to spin down on the dyno (MD-250) than a MK-II.

The torque ‘curve’ on a 1Z with stock cams is flat. This is true in both N.A. and mildly boosted forms. It starts at about 2000rpm, has a slight bump up around 4400rpm where maximum VE occurs and remains flat until redline. Any sudden or gradual drops or peaks indicate a problem with the car, its tune, the dyno or it’s operator.

The layout of dyno charts is configurable. Don’t accept the shop defaults, ask them what they can do to change it be what you want to see. Here’s what like to see…No corrections factor, no smoothing. 4th gear for power pulls.

Bill Sherman Page 12 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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The x-axis (horizontal) scale should be in RPM not vehicle speed. It should start at 3000 rpm and increment in 500rpm intervals to 6850 or just before your rev limit .AFR plot showing ratios between 10:1 and 15:1 for the full run not just min, max & avg.The y-axis (vertical)  TQ and HP scales on opposite margins. If they don’t intersect at 5250rpm ask why different scales are being used. Tuning VS PowerPullsIt’s their shop, their equipment, their reputation and you should be able to trust them to know how to protect those things while making good power with your setup. But if they blow your engine for any reason Oh well. Pay to play.

I haven’t been to a shop that didn’t let me change the setup between pulls. I’m sure there’s some that don’t allow it and they’re probably very good at what they do but I would be suspicious of one that only let me observe from behind a glass wall, in a leather chair with a latte.

Bring a modification list so the tuner knows what he’s dealing with.Bring an OBDII scan-tool, laptop, and infrared thermometer. Log everything.Note on each chart the oil, ambient and engine bay temperatures, plug gap, fuel pressure, pulley size , total timing, map#, and boost so they will make better sense to you later.

The biggest factors affecting tuning time and cost are:

1. Your expectations. How close to the edge are you willing to go? Do you know where it is. Does the shop?How long does it need to last? Are you F&F living your life 10seconds at a time?How much can you afford to pay? Don’t spend $3k to tune a streetcar or $300 to tune a track car.

2. Sophistication of EMS. A standalone has much more control than a piggyback. Greater capabilities generally take longer to dial in but yield better results.

3. Shop knowledge of multiple EMS's. Do they have base maps for your setup or will they have to start from scratch? The more systems they install the better they'll be able to sell one that fit your needs. If the only tool they have is a hammer then all their problems have to be nails. You wanna be someone’s nail? Well do you?

4. Tuner skill level with your EMS, your engine, your power levels. All 3 are critical. Give a Motec M600 to a muppet and he'll blow your 1Z at 200hp. A certified Greddy/AEM shop should be able to safely reach 300whp on a built 1Z streetcar using an Emanage or FIC piggy.

A note on Water/Methanol InjectionShould you decide to go with chemical charge cooling FOR POWER then CLICK HERE Don’t expect every tuner to be comfortable with it. Some will inject it on top of an

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already overly rich tune just to prove to themselves “See, this stuff just don’t work.”. Others, may flat out refuse to create a tune that depends on it. Its their shop…

Aftermarket CAMS

The 1Z head is not a hi-performance unit and can’t be made into one.Removing the valve cover is heading down the wrong path and totally unnecessary for F.I. You can port & polish a 1Z head all day long then overbore it, raise the CR to the sky, fill the block with epoxy and run it on race gas but there’s only 30-60 N.A. HP to be had. Nothing to sneeze at in a 2200lb car but is it worth the cost, downtime and effort?

Low boost F.I. will make more power, for less $. And it will do so at much lower tensile loads and wear rates than raising the rev-limit ever will.

Fully built MWR N.A. 1Z puts down 166hp on race gas

The most built-up N.A. 1Z on SC put down 158whp on pump gas$1000 MWR 1.9L kit Wieseco 11.0:1 pistons. (Heads can be machined to ~11.8:1CR)  $500 Block machining$600 MWR springs, stock valves. $200 AEM intake.$500 PPE header and cat-less test pipe.$600 Apexi N1 exhaust.$425 Crower stage III cams$500 MWR oil pan.    $1000 Apexi PFC.        $250 2 hours of tuning at $125. WAG – Maybe he got it for free?--------$5575 to gain 36hp and 27ftlbs = $154/HP

A less expensive route using stock cams. $200 - TB rebore$100 - Port match intake&exhaust manifolds$300 - Machine 1Z head (resurface, 3-grind valve job, $600  - Aftermarket springs and valves$1000 - EMS such as PFC or Emanage Ultimate + V-manage module. Raise the rev-limit $500 - Tuning. Know a good one because it adds up fast @ 125/hr----------2700

What happens when you get bored with 160-190Chp?Good news is your only out the tuning $ because F.I. will benefit from the headwork..Bad news is you could have added twice as much power (100hp+) for the same price without doing any of the above and without opening the head.

Bill Sherman Page 14 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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CAMS for F.I. are Unnecessary on a STOCK 1Z because…

The stock cams are more than sufficient. It makes more sense to replace the rods and pistons FIRST.

Approaching 400Chp puts the weight/power ratio at 5.5. Well past the point of “traction challenged” and into the realm where plain streetability can be a concern. Valves & springs and a built bottom-end are all that’s required to get there.

So when do aftermarket cams make sense?

1. N.A.1Z that revs to 8000rpm and doesn’t care about low-mid range losses.

2. Turbo 1Z at 400hp+

3. Turbo 2Z at 500hp+

4. For the hell of it

Stock ZZ Engine Cam specs

CROWER Cam comparison to 1Z

Bill Sherman Page 15 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Fuel and Ignition Upgrades

Fuel Injectors are top feed and hi-impedance 12-14Ω.Do not use resistors to fit low-impedance injectors when running a piggy-back EMS.

There are 7 commonly used injectors on ZZ engines.

1. 00-06 MKIII MR2 GREEN rated at 252cc/min Lag time .806ms 2. 00-01 Celica GT-S YELLOW rated at 310cc/mm. Max 210Chp at 38psi 98%DC3. 2002+ Celica GT-S BROWN rated at 330cc/min Max 220Chp at 38psi 98%DC

4. Bosch P/N 0280-155-868 WHITE and flow 380-410cc/min.Max 275Chp 38psi and 98%DC. Fit stock rail and head but need a square electrical clip.

5. Blitz P/N 31209 are BLUE rated at 525cc/min Same as 02-05 Subaru WRX Sti? Lag time .99ms

6. Power Enterprise P/N TH550A-C are BLUE referred to by PE as “550cc/min,” actually rated at 525cc/min. Visually similar to Blitz P/N 31209, unconfirmed if these are “rebadged” parts. Replaces stock injector clips. Lag time 1.1ms

7. Siemens DEKA IV are BLACK and rated at 630cc/minBoth ends need be lathed down to a10mm O.D. to fit the stock rail and head. They the same electrical clip as the Bosch 380’s. Turn on time: 1.14ms @ 14VDC, Turn off time: 0.85ms @ 600KPa.

Injector sizing calculator http://www.rceng.com/technical.htm#WORKSHEETThere has been some speculation that the 1Z BSFC may be as low as .45.Keep in mind, a street car can run the DC into the 90’s whereas a track car shouldn’t. For reliability, it is recommended that injectors not be run at greater than 80-85% DC for extended durations.

Aftermarket injectors are commonly rated at 43.5psi therefore, unlike vehicle’s running 60-80psi stock such as the Dodge Srt-4, a return fuel system would’t be required until a little over 300Chp; however, the need for a return fuel system is still a subject open to debate. 300whp has been achieved using 660cc injectors and an otherwise stock fuel system. There is a degree of uncertainty as to how long or how much more than stock pump can take without giving up the ghost, but if the pump is upgraded, it may be sufficient for much more with converting to a return style. These limits have yet to be tested or proven. (ref: http://spyderchat.com/forums/index.php?showtopic=55642&st=0)

Injector sizing calculator http://www.rceng.com/technical.htm#WORKSHEETThere has been some speculation that the 1Z BSFC may be as low as .45.Keep in mind, a street car can run the DC into the 90’s whereas a track car shouldn’t.

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Aftermarket injectors are commonly rated at 43.5psi therefore, unlike vehicle’s running 60-80psi stock such as the Dodge Srt-4 , a return fuel system isn’t required until a little over 300Chp.

Toyota Coil On Plug Ignition

Both ZZ’s use a 12 volt coil driver circuit not 5v like your ‘bro’s Honda. There are no distributor, plug wires or “MSD” upgrades that work. Upgraded coils have to be run with a standalone EMS because the stock ECU expects to see a confirmation signal every time it fires a plug. But no one has ever reported any trouble making fire on the stock hardware well into 20#’s of boost as long as plugs are re-gapped to .025 to -035, dependent upon the application.

As a point of reference, on a setup using NGK Copper V Power Plugs P/N BKR7E-11’s re-gapped at .032 on an 8.8:1 compression 1zz engine, spark was blown out around 14 psi. Re-gapping the plugs to .025 resolved spark loss and held strong up to 17 psi.

The stock plugs are Denso iridium (IK-16, as mentioned earlier) and are pre-gapped at .044 and must be re-gapped for F.I but DENSO does not recommend re-gapping Iridium.

Changing to different types of plugs is not as much of an issue for N/A cars, though some prefer copper over iridium for its superior conductivity. The trade off is that while iridium plugs last much longer, copper plugs should be changed out roughly every other oil change. Another downside to iridiums is that the tips are very brittle, which makes some people iffy about running them in boosted applications for fear that a piece could break off inside the cylinder under less than ideal conditions.

Some have reported that going to copper plugs has resulted in a “cleaner burn” and less “backfiring.”

For boosted applications, heat range selection can vary depending upon factors like how much boost you are running and whether you are still at the stock 10:1 compression or if you have rebuilt the engine for say, 8.8:1. As a general guideline, with any amount of boost you should go at least one range colder than stock. This may be adequate until roughly 1 bar (14.7 psi) of boost, but it will vary depending on the application. If you notice the plug deteriorates in any way, you should back up one range. The colder your plugs are, the more resistance you should have to detonation, but it can detract from the efficiency of the engine off boost.

Copper plugs that are suitable/recommended replacements: Note –11 indicates a gap of 1.1mm or .044” This is too wide for anything over 5-7psi.NGK Copper V Power Plugs P/N BKR5E-11  (stock heat range)NGK Copper V Power Plugs P/N BKR6E-11 (1 step colder)NGK Copper V Power Plugs P/N BKR7E-11 (2 steps colder)

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Known Ignition issues 1.Exploding intake manifolds. The EManage piggybacks cycle the ignition circuit when the key is turned to (ACC/ON). This may ignite any fuel vapor from a leaky injector.

2. Coil pack can short out if water get into the plug well.

3. This is more of an issue for the J&S Safeguard as it relates to the 1zz ignition. For anyone who may acquire one, some of these units will blow an ignition fuse upon attempting to engage the ignition unless it is changed to a higher amp fuse.

Cooling System Upgrades

Even though 1/3rd of the heat generated ends up in the cooling system, none of these upgrades are straightforward propositions for a street car. Some may do more harm than good. Research….

1. 160° TRD thermostat – Stock ECU has a 176* threshold for several reasons.2. KOYO radiator – May not help a street car AT ALL.3. Manual fan controller - Reduces reliability if driver doesn’t turn it on or off.4. WaterWetter – Prefers to mix with H20 not ethylene glycol. Ice may form!!!!5. 2Z WP Swap – No hard proof that it helps, impellers may hit block w/o

clearancing.

Its been speculated that the stamped steel impeller of the 1Z WP is less than optimal and might cavitate when spun above ~4500 rpm because water can get behind the impellers. As far as I know, the only 'proof' ever offered is that Toyota used a different impeller design in the higher revving 2Z engine. As both engines will accept either pump flange the reason may have been to reduce the costs of the much more common 1Z.

Everything is based on this line of thinking. Nobody honestly knows if the 1Z WP cavitates at all or if it does, at what RPM or how much worse it is at 5000 vs 6500rpm.

I believe the stock 1Z WP is adequate for a street car up to 300fly/260whp HP because...

1. In practical terms, a daily driven street car might see 10 seconds of sustained WOT operation 2 or 3 times a day if the owner is unconcerned with speed limits. There will be frequent but much shorter boost intervals occurring perhaps dozens of times daily. Under these conditions, the excess heat created will be quickly absorbed and dissipated by the stock cooling system because ...

2. The MKIII MR2 already has a greater cooling capacity than any other 1Z platform due the distance between the radiator and engine.

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Raise the rev-limit and/or go for big power then the 2Z WP is a no-brainer because it’s a straight swap. May have to clearance the impeller a 1/64th so it doesn’t hit the inside of the block. A 1730 to 1745mm belt works if the A/C is retained.

Pulleys:The 1Z pulley is welded to the pump shaft, the 2Z is bolted. Non-interchangeable.The 2Z pulley is larger so it underdrives the pump. A larger pulley will slow the accessory down, and a smaller pulley will speed it up. There have been no reported heating problems driving the 2Z pump slower on a 1Z on street or track.

Oiling System Upgrades

Sure are lots of things that might be done if money grew on trees!

Most of these also have compromises but unlike the cooling system upgrades, damage might be done if you DON’T do them.

Recommendations: Switch to full synthetic oil, especially for turbo applications. Compared to mineral-based oil, synthetic oil has a stronger and more uniform molecular structure, less frictional losses, more high temperature stability, more resistance to break down, and resists coking of bearings in turbos. For turbo applications, also avoid oil with a wide multi-viscosity range if possible to further guard against coking.

Epoxy neodymium magnet to the outside of the stock drain plug.

For any ZZ seeing g-forces (track, autocross, donuts): 6QT Moroso pan.

For a mildly boosted stock internal ZZ streetcar in a mild climate: 3,5 & 7 should suffice.

For a high boost, built engine or mildly boosted stocker in a hot climate:2 thru 7

For a dedicated track car who cares! It’s the sponsor’s money!!

1. 1Z Piston oil squirters. Custom machining required.

2. 6QT Moroso pan. From MWR – Same one fits both ZZ’s

3. Oil cooler. Thermostatically controlled radiator style with ½” hosing.

4. TOGA OPT039L-HV oil pump or stack the OEM relief spring or install Circuitworx gears.

5. Instrumentation to monitor temps and pressures.

Bill Sherman Page 19 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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6. Turbo oil inlet 1mm restrictor to go with HV pump.

7. Maintain the OCV filter screen/s.

8. Remote relocation of oil filter.

9. Accusump oil accumulator/re-oiler

10. Magnetic drain plug. The cheap one’s come apart/magnet sticks inside the pan.

11. Lowering the oil pickup on stock pan. Don’t dent the pan on a curb if you do this!

12. Crank scraper/Windage Tray from www. crank -scrapers.com

Bill Sherman Page 20 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

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Crank Case Ventilation

In any gas engine, pressure is created in the crankcase as the result of combustion gases leaking past piston rings (down into the crankcase) and past valve guides & seals (up into the valve cover). Without an exit to vent the pressure, the weakest seal will eventually fail spewing hot oil into the engine bay. Before environmental laws were passed these gases were ventilated directly to the atmosphere. The new laws required they be sent back into the engine and burnt. That’s why the Positive Crankcase Ventilation system was created.

In a F.I. conversion, the intake manifold becomes pressurized under boost disabling the PCV system. This will eventually turn the oil into engine killing sludge. But more immediately, as in right away, the crankcase becomes over-pressurized forcing the oil up the return line, past the turbo seals and into exhaust pipe creating a smoke cloud. It can also get into the I/C piping, fouling the intercooler, MAF and throttle body. This reduces drivability and increases the chances of detonation. It also makes a mess.There are at least 5 different ways to address this* Here’s the two most practical for a ZZ.The Minimal SolutionCut the 5/8th" hose that's located next to the oil filler cap on the intake side of the head. It needs to vent to atmosphere. Cap the throttle body side. Leave the ½" line connecting the PVC valve to the intake manifold alone.. The KrankVent with Catch Can SolutionInstall a one-way KrankVent on both lines and a catch can on the PCV valve line as depicted. The will help create a partial vacuum in the crankcase and that helps the turbo oil return to drain and purportedly helps rings to seal.

*Other solutions include the factory turbo style, drag racers vacuum pump and the hot rodders exhaust scavenging head breathers.

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Power Supporting Modifications

There are big questions to answer before even beginning like … What’s the power goal, budget and build schedule and how do the supporting mods fit into all that?

Turbo or Supercharged? Do they require emissions testing where you live?

Will it be totally custom or kit based? Its not a good idea to attempt a custom F.I. conversion without ever having done one at all before.

How much work can I do myself? Is life stable enough to attempt this? Am I stable enough? How would one know if one wasn’t☺

1. Getting the power to the ground.

a) Transmission – 5MT vs 6MT final drives & gear ratiosb) LSD - Viscous, clutch 41301-ST804 or OEM/TRD helical P/N 71301-ST900

OEM Helical P/N 41301-20230 from Japanparts P/N 014-108-41301

c) Clutch - TQ capacity, disc or puckd) Tires and wheelse) Suspension - Inserts, coilover or Sportivof) Brakes

2. Managing Heat

a) Thermal coatingb) Shields, Sleeves and Wraps

3. Component Mounting, Bracing and Routing,

a) Turbo & S/C access hatch b) To Intercool or not A/A, A/W, W/A, FMIC, BMICc) Motor Mounts – stock, full replacement or insertsd) Oil cooler location, boost lines and gauge wires.

4. Intake and Exhaust

a) Manifold type, flow estimates pipe sizing (1” per 100 HP) and routingb) Piping design (size - efficiency vs. noise, price - stainless vs mild steel

etc…)c) Cat or straight piped) # of O2 sensor bungs 1,2,3 or 4e) Any EGT probes?f) Water/alky injector bungg) Relocated IAT sensor bungh) Air filter type and placement

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i) Boost control internal/external WG,EBC or MBCMj) MAF and or MAP MAF Location in a turbo conversion DRAW or BLOW

5. Instrumentation

There’s so many opinions and options that the research is yours to do. But the minimal are a boost and wideband permanently mounted in the cockpit. . If you do any hard driving (such as track, autcross, canyon carving) an oil pressure and oil temp gauge are also highly encouraged, as alluded to in the oil system upgrades section. This is considering the history of oil starvation with the ZZ engines and the extra heat and vulnerabilities introduced to the oil system by a turbo setup.

A. The dashboard dimming dial is a rheostat that cannot be used to control aftermarket gauges brightness.

B. The cigarette lighter circuit is sufficient for all the gauges listed below.

C. Put expense gauges like the WB on a proper fuse or fuses.

D. Do not run mechanicals for any liquids (oil, gas, water). Use electric.

Here’s a part/price list for six 52mm gauges and their supporting mods☺

WideBand O2 LC-1 and XD-1 $399 InnovateMotorsparts #3765 1VDO Boost Gauge Came with Hass kit 2Custom A-pillar gauge pod $67 GB Spyder chat GBFuel Pressure Gauge $90 Cyberdyne 280-A211E061Y from jegs.com 3Oil Pressure Gauge $62 Cyberdyne 280-A210E060N from jegs.com 4Oil galley block adapter NPT to BSPT $10 Autometer P/N 2269 for oil pressureOil Pressure Sender $22 Cyberdyne 0280senss2e Oil Temp Gauge $36 Cyberdyne 2 1/16 70-260F 5Oil Temp Sender $14 70-260f 1/8 NPTECT Gauge & Sender $48 2 1/16th 70-260f and 1/8NPTsender 6ECT sender 30m hose adapter $25 DEFT 1/8NPTBosch LSU4 WB Replacement Sensor $40 www.parts.com 021-906-262-B

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Emissions Testing

Onboard Diagnostic Overview

Strictly speaking, if your locale has periodic emissions testing, the vehicle must have all three stock O2 sensors, a catalytic converter, the stock ECU and a working CEL.

By using a piggyback or a standalone EMS in piggyback mode, many (including myself) have retained the stock emission equipment and successfully passed OBDII testing while making double the factory power. The car will drive in and out of the testing station just like stock and no one will be the wiser. A supercharger may even pass a visual inspection but a turbo sure wont.

The no-holds barred, power-with-full-control-approach requires a standalone. In this case, you will need to swap in the stock ECU, smaller injectors using the stock injector clips, smaller MAF piping, bypass the S/C pulley and install the three O2 sensors or their simulators. So, if you go with a standalone, be sure to have three O2 sensor bungs in your setup or learn how to spoof the signals so the stock ECU doesn’t pitch a fit when its time to test.

OBDI ready flags and two-trip logicAnytime the stock ECU is disconnected from battery main power all OBDII readiness test flags are turned off and wont be re-enabled until the vehicle has been run long enough for the stock ECU to realize there’s no condition present that will cause a two-trip logic DTC. This is why clearing the CEL with a scanner or battery disconnect while waiting in line at the testing station doesn’t work. Sure, the CEL goes out but the ready-test flags are now ALL unset. Toyota two-trip logic is defined as two consecutive driving cycles where the car has been driven for 15minutes or longer, during which, the coolant temp reached 176 or higher and a speed of 40mph or greater was achieved.

A return style fuel system reportedly unsets one of the ready-to-test flags Starting in 2001, you can have only one flag un-ready. ’96 – ’00 vehicles can have two.

Spoofing the ManThe list on the next page contains the 13 DTC codes associated with O2 sensors. Any one of them will light the CEL, undoing the associated ready-flag/s and cause the vehicle to fail on sight.

The stock ECU is expecting a total of 7 O2 signals to be present. Two for each A/F sensor in the exhaust manifold (circuit signal & heater load) and 3 for the post-main cat O2 (circuit, heater and cat efficiency)

O2 Sensor signal (2)The Split Second ESC1 will spoof the O2 circuit signals that the ECU uses for fuel trims. The better option is to feed the 0-1v analog signal from your WB controller to the stock ECU on pins E12 and E21.

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Heater circuit signal(2)The three heater circuits require at least a 10w25Ω axial resistor because the ECU is looking for 23Ω to 32Ω of resistance corresponding to 800°F before turning off each heater circuit.

Main cat efficiency (1) PO420Thread the final O2 sensor into two stacked Sparkplug anti-fouler’s in a straight pipe to spoof the post main cat signal.

Stock Sensor Info

Heated 4-wire Oxygen sensorsThe stock sensors are physically and functionally equivalent and can be swapped with one another, left to right and top to bottom. The post main cat sensor has a different P/N and harness length but just cut the wires and swap. Universal 4-wire sensors are typically half the price of OEM.

HO2S Wire colors 2Z are probably identicalBLUE = SIGNALWHITE = SIGNAL GROUNDBLACK = HEATER CIRCUIT. Doesn’t matter which goes to which there is no polarity.

Bank-1 Sensor-1 Monitors the outside cylinders 1&4 and is located on the passenger side - ECU pin E4-12

P0130 O2 Sensor Circuit Malfunction P0133 O2 Sensor Circuit Slow Response/No Activity DetectedP0135 O2 Sensor Heater Circuit Malfunction P0171 System too Lean P0172 System too Rich

Bank-1 Sensor-2 Monitors the main cat down by drivers side rear wheel. P0136 O2 Circuit MalfunctionP0141 O2 Sensor Heater Circuit Malfunction P0420 Main catalytic operating below minimum threshold (two trip logic)

Bank-2 Sensor-1 Monitors the middle cylinders 2&3 and is located on the drivers side - ECU pin E4-21 P0150 O2 Sensor Circuit MalfunctionP0153 O2 Sensor Circuit Slow Response/No Activity DetectedP0155 O2 Sensor Heater Circuit Malfunction

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P0174 System too Lean P0175 System too Rich

O2 volts and relative Air Fuel Ratios 0.1=17:1 0.2 =16.5 0.3 =16:1 0.4 =15.4 0.5 =14.9 0.6 =14.4 0.7 =13.8 0.8 =13.2 0.9 =12.7 0.985= 12.1

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Mass Air Flow Sensor Type: Toyota Hotwire DENSO P/N 22204-2101 It has been found through trial and error that the MAF voltage is somewhat erratic and laggy if there is nothing to smooth the airflow out before the MAF. This can be vanes, similar to stock, or some have also reported a honeycomb insert (Mcmaster-Carr P/N 9635K33) as being effective as well.

Upgrading the MAF housing’s inner diameter will slightly “desensitize” the MAF, allowing it to read more airflow at a lower voltage. A better solution, if doing one or the other, would be to upgrade the MAF sensor itself.

The IAT and 2-wire MAF do not share the same ground and the IAT does not need 12v power.

1 - B+ - Solid Black = MAF 12v Pin16(A) from the EFI2 fuse block2 - E2G - Black w/Red = MAF ground Pin1(C)/EVG3 - VG - Solid Purple = MAF signal Pin11(C) on ECU4 - THA - Yellow w/black = IAT signal Pin12/C)/THA on ECU5 - E2 - Solid Brown = IAT ground Pin18(C)/E2 on ECU

The original option pioneered by some was to rewire the MAF sensor plug to work with a Gen IV Toyota Supra MAF.

Turbo Supra MAF P/N /22250-46030 From 1995 and newer.2.75” intake side and 3.25 “ IM side1 - B+ 2 - VG 3 - THA 4 - E2 5 - E2G

Subaru/Denso MAF

One alternative that is rapidly gaining in popularity is to swap to a “plug and play” Subaru/Denso MAF sensor. This MAF is shared among many 2004-2007 Subaru vehicles including the WRX, Sti, Forester, and likely others not yet discovered. This sensor plugs directly into the stock MAF plug without any rewiring. Rather than attempting to rescale the airflow curve on a standalone such as the Power FC, several have successfully opted to simply do a full retune for simplicity’s sake.Denso part number: 197400-2090Subaru part number: 22680AA310

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Intake Air Temperature (IAT) sensor

As indicated above, the MAF housing also contains the IAT bulb. If your MAF is so located that accurate IAT’s are unobtainable then it really must be moved or the engine timing will be suboptimal The most common reasons in a turbo application are because the MAF is:

1. In an un-pressurized intake pipe before the compressor housing.(reads cooler)2. In a pressurized pipe before the A/A or A/W intercooler (reads hotter)3. In a pressurized pipe after any I/C but before the W/A injector. (reads hotter)

These P/N’s use a standard 3/8" - 18 NPT thread. Be sure to get the weatherized two wire pigtail electrical connector and splice it into the yellow/black and brown wires on the MAF plug.

1. GM #25036751 2. Standard AX1 3. GP SORENSEN 779-19001 4. AC DELCO 213-190 5. NIEHOFF IGNITION TS83631 was DR-136W 6. WELLS SU107 MSD 2320 (includes connector)7. ECC72-4514

Engine Coolant sensor (ECT) and the Crank & Cam These sensors are not an issue for FI. Don’t even think about screwing with their signals. No you cant “lower” the ECT to keep the ECU in cold-start mode to get more fuel. It will pitch a fit and go into fail-safe mode.

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Stock ECU Facts

The ECU is in Open-Loop during these 5 conditions only:

1. Cold Start for 180 seconds or until O2 sensors heat up.2. Warm Start until it has enough sensor data for o2 feedback3. Hard Acceleration – based on load and environmental conditions4. WOT 5. Fuel cut 1400rpm and rev-limiter

That’s all well and great but boost-fanatics want to know WHEN does the ECU leave closed-loop? Well, there is no one point where the ECU enters open loop under hard acceleration. It can be as soon as 33%TPS or not until 5000rpm or some other place depending on conditions and load.

If your scanner doesn’t actually display open loop status then it can be found by watching the O2 sensor voltages.

Start in 1st gear at 2000rpm with the coolant up to at least 176F. The O2 voltages should be bouncing.Slowly raise the RPM until the O2 signal/s goes dead rich and stops bouncing.Note the RPM/TPS where the O2 stop dithering.Start in 4th gear at 2000rpm and repeat. Note the RPM/TPS where the O2 stop dithering. Was it the same as the 1st gear run?

Throttle Position Values TPS% Toyota spec My car IDLE 12% 0.3 – 1.0v 0.63WOT 79% 3.2 – 4.9v 3.98

*The range of voltages should be solid and always the same for any given car but they will differ between vehicles..

FAIL-SAFE MODEFrom page DI-8 of the MR2 ’00 BGB

The stock ECU enters FAIL-SAFE mode under 5 conditions.

Cause __________ DTC/CEL Result until Fixed___________________1. IAT sensor failure PO110 Intake temps are set to 68F* 2. ECT sensor failure PO115 Coolant temp are set to 176F* 3. TPS sensor failure PO120 Throttle position set to 0° 4. KNK sensor failure PO325 Timing retarded maximal until IGN OFF.5. IGN Circuit failure P13XX Fuel cut

Bill Sherman Page 29 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.

Page 30: Power Quest an Enthusiasts Perspective

Power Quest – An Enthusiasts’ Perspective* on the MK-III MR2

Revision History

04/26/08 Initial release04/27/08 MAF location argument BLOW or DRAW

05/11/08 Add link Epoxy neodymium magnet link to page 17

05/18/08 Add link to 2ZZ MMC liner on page 2

08/05/08 Add EGT note on page 8

08/31/08 Add O2 volts AFR on pg 22

08/31/08 Add clutch P/N’s to page 19

10/05/08 Added link to Curt’s Rotrex install, updated Fuel, Ignition, MAF sections, and other miscellaneous additions noted in RED. Thanks to KingSpyder

10/6/08 Create Table Of Content and changed the Honda F20 reference to K20

Bill Sherman Page 30 4/9/2023☻ My ’00 1Z MR2 has had multiple crank HP levels: 138hp, 160hp, 270hp and headed for more.