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700 Series TBIThe TBI used for 87-88 Fiero 4 cylinder motors isthe 700 series unit presently manufactured byDelphi Automotie for !"#$ou can find Delphi%s public relations info for the700 TBI here#The information includes ima&es

and &eneral specification data# The articles that 'e%re interested in at themoment are (Throttle Bodies - Sin&le )oint* and (Throttle Bodies - "ultecBottom Feed#* The first is the TBI unit and the second is the in+ector in moredetail# Fiero uses the lo'-pressure ersion# ,ote. Delphi chan&es thin&s fairlyre&ularly# If they still e/ist these documents may be hard to find# I can1t postthem due to copyri&ht#2Belo' you can see ho' the TBI is setup and 'here some of it1s components are#I also noted the "AT sensor for you# ,"AT is also coered in the DIS article#2

FPR, Fuel Pressure Regulator TPS, Throttle Position Sensor IAC, Idle Air Control motor F In/Out, Fuel Lines MAT, Manifold Air Temperature

The desi&n of this TBI is really somethin It can tolerate ama3in& amounts ofcrap in the fuel system 'ithout plu&&in& the in+ector# There are screens ri&hton the in+ector# $ou%d hae to coer them nearly completely to bloc offin+ector flo'# To &et that much trash to the TBI both the main filter and thepicup soc in the tan 'ould hae to fail or you%d hae to hae ma+orcorrosion dama&e to the inside of the fuel lines#

The 700 TBI is comprised of t'o modules# The upper section handles all thefuel meterin& and is the same re&ardless of 'hat lo'er section is used# Thelo'er section handles all the air meterin& and contains the throttle plate andIA5# There is no fuel flo' bet'een the modules e/cept 'hat flo's from thein+ector tip# 700 TBI bore diameter is determined entirely in the lo'er section#,If you 'ere punchin& out a 700 you 'ould only machine the lo'er half# Thelo'er section assumin& there is enou&h metal can be punched to thema/imum diameter of the upper half#2BT6 the TBI used for 87 and 88 Fiero 4 has a 4mm diameter main bore# Thelar&est Delphi maes is 48mm# $ou could install a 48mm one but you1ll need toream the manifold and you probably 'on1t &ain much po'er#

Do I need to use in+ector cleaner in my &as9

)robably not# The cleaners already present in most pump &as should be morethan enou&h# :eep in mind that this in+ector is not bein& heat soaed lie portin+ectors are after en&ine shutdo'n# It%s far from the intae ales andupstream of the throttle as 'ell# That preents fuel residue from cooin& ontothe in+ector#

http://www.delphiauto.com/http://www.delphiauto.com/http://www.delphiauto.com/http://www.delphiauto.com/http://www.delphiauto.com/

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The only time I can thin of 'here cleaner mi&ht help is if the car sat paredfor a lon& time# That should help 'ash a'ay anythin& caused by stale fuel#6ith this system if you are findin& allot of carbon in the TBI and intae thenyou hae problems deelopin& that need more than some cleaner# ,$ou 'illliely also need to chec;replace the "AT sensor#2

Throttle )osition Sensor

The T)S is not ad+ustable# The ne terminal 'ill sho' ?# Another terminal is &round# The last is the output#The T)S output should sho' less than @# olt 'hen the TBI is at idle# >utputolta&e should increase smoothly bet'een idle and 6>T# ,ote. It is usuallyeasier to test the sensor 'ith an analo& meter# Di&ital displays are often too+ittery#2

The In+ector

ote. Don1t rely on the isual appearance of the in+ector output# In most casesyou 'on1t be able to tell a &ood spray amount;pattern by eye# These systemsnearly al'ays loo lie sho'er heads 'hen runnin :eep in mind that unlieport fuel in+ection fuel from the TBI has plenty of time to mi/ on the 'ay tothe cylinders# The TBI is also on a heated manifold +ust lie a carburetor uses#If the in+ector is leain& it 'ill tend to do that as soon as the systempressuri3es# The most common lea is >-rin& failure but it is possible for thein+ector to lea internally#The in+ector used in these is built lie a tan# I don%t thin I%e heard of morethan one or t'o that 'as actually bad# I%d say C of the time if the in+ector

'eren%t firin& that you need to chec the fuel pressure and the si&nal from the

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$ou can &et noid li&hts at many parts stores# $ou can &et 'hole sets of themonline from arious sources#

Idle Air 5ontrol motor

5ontrary to popular belief the IA5 is ery 'ell desi&ned and 'ill last nearlyforeer under most conditions# If you thin there is an IA5 problem your firstpro+ect should be checin& for acuum leas and >T spray the IA5 'ith (carb* cleaner# If you must try to clean it useelectronics parts cleaner# Stron& solents can eat the insulation off the coils#$ou can no' &et test ,(noid*2 li&hts for IA5 as 'ell as the in+ector# I1e seenthese for about E@0 at )ep Boys#Ideally you1ll use an IA5 noid 'ith an T use&aset sealer on it= If it leas then it needs to be replaced#The fuel pump on the other hand is a common failure item especially if you%erun the tan dry# The fuel flo' cools the pump and it 'on%t tae lon& to coo'hen runnin& dry# ,This is true of the many inds of pumps not +ust fuelpumps#2The Huic test for no or lo' pressure is to pinch the fuel return line and see ifyou &et pressure# This may help if the re&ulator is bloced open but probably'on%t do a thin& if the pump is batty#There is a fuel pressure &au&e set aailable for TBI and other lo'-pressuresystems that don%t hae Schrader ales# The set includes and adapter thatsae you from cuttin& the line to install a T# These sets are e/pensie typically

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oer E0# $ou may be able to borro' one from some parts stores# ,Thee/pensie part is the adaptor that installs bet'een the fuel line and the TBIbody so you can connect the &au&e#2

Fuel Filter

It%s under the car and can be a real pain to chan&e#$ou 'ant to chan&e this eery so often lie once a year or so# These filters arebuilt lie a small oil filter internally and hold a tremendous amount of &arba&e#The only 'ay I can thin of that you could plu& the thin& are if the fuel line is&oin& bad or if the picup soc in the tan fails# If you seem to loose fuelpressure after the car runs for a 'hile the filter could be the problem#If you are &oin& to remoe the filter for any reason then +ust replace it# Theydon1t cost ery much and you can usually &et them een cheaper at places lie6al-"art#

Gepair Gebuildin&

When installing the IAC motor, make sure the pintle is

retracted. DO NOT force the IAC motor into the throttle body Ifthe IAC motor !ill not easily seat fully in the body then the

pintle is too far out. "ou should be able to seat the motor fullyinto the throttle body !ith little effort.5arefully chec the TBI mountin& holes in the manifold# These holes can bedama&ed if the air cleaner has impacted the trun 'all# ,Gead the torHue strutarticle#2 If the holes are stripped you1ll hae to use Jelicoils on them#

If the throttle shaft is badly 'orn find another TBI unit# $ou should be able tofind these fairly easily at any sala&e yard# >ther'ise the 700 unit is ery easyto rebuild#Don%t mess 'ith the idle stop durin& rebuild= There%s no reason to fool 'ith it#The rebuild its include the fuel pressure re&ulator diaphra&m# If the F)Gdiaphra&m is bad then +ust buy the rebuild it and be done 'ith it# The it isn%tthat much more than buyin& the diaphra&m and you &et all the &asets >rin&s and screens# $ou essentially end up 'ith a ne' TBI unit#The rebuild it usually comes 'ith more &asets than you 'ill use# The last oneI bou&ht came 'ith three mountin& &asets and t'o body &asets# $ou shoulduse the replacement &aset that matches the ori&inal#

Assembling and Mounting the TBI

6hen you put the t'o hales of the body to&ether torHue the scre's tospecification#After you torHue the mountin& bolts chec the body scre's a&ain and torHueas needed to reach specification# The mountin& bolts often cause the body

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bolts to loosen# If you don%t chec them the upper body could 'arp and causean air lea#

Jard'are TorHue

Fuel meterin& to throttle bodyscre's K in;lb , m2

TBI to manifold bolts @8 ft;lb , m2,Source. Adata2In case you don1t hae a ?'ners "anuals and otherinfo#

http://www.helminc.com/http://www.helminc.com/

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ADATA DI$is a &ood source# This is the online ersion of the 5D;D?D productthey are 'ell no'n for# 6hile you can 'or directly from their data I usuallyconsider them a supplement to other sources includin& the Jelm boo#ADATA has all the TSB and Shop "anual updates you +ust can%t &et any'hereelse# If the online ersion allo's printin& I%d say +oin them for a year and print

eerythin& you can &et your hands on# ,I stron&ly recommend a laser printeroer an in +et# "ost in +ets are liely to eat multiple cartrid&es doin& this#2

Adjustment Procedures

The only ad+ustment possible on the 700 is to the idle stop scre'# 6ith thepossible e/ception of ne' replacement units there is no reason I can thin ofthat you should eer ad+ust the idle stop# All the ones used on # liter motorsshould transplant 'ithout chan&in& the idle stop#The only reason I%m coerin& the idle stop ad+ustment is because eery so oftenyou run into a motor 'here some hac has scre'ed it up# $ou%ll no' if that%s

happened because the Idle Stop seal 'ill hae been remoed#

Idle Stop

$ou1ll need an

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If you do &o looin& for a 48mm unit chec the intae manifolds and head oflater model DIS 4 as 'ell# This could sae modification of the stoc manifoldand may &ie you lar&er intae runners etc#The reason I say this is that !" specified the @ >lds 5utlass 5alais ,?I 92Iron Due at @@J)# I1e seen that motor once and only e/ternally# It looed

identical to the @88 en&ine# ,Balancer motor#2 They had to rin& out the e/trafrom someplace#In reality you1d be better off seein& if the @@ en&ine 'ould 'or in Fiero andthen buildin& that up if needed# That &ies you an en&ine - years ne'er as abase# I couldn1t see 'hy it 'ould not but I haen1t been able to really di& intoone yet# $ou should be able to &et one for about E00-K00 from a local sala&eyard# ,I beliee @@ 'as the last year for this en&ine#2If you do that mae sure you also &et its " but you1d loose updated code in the @ )G>"# Theori&inal Fiero )G>"S hae a fe' minor issues###2

Fuel Pressure

Accordin& to 'hat I1m told you can mae the fuel pressure re&ulatorad+ustable# If you try this do it to a spare re&ulator coer# It inoles cleanin&out the sealer;solder oer the re&ulator scre'# $ou may also need a lon&erscre' and a +am nut to preent the pressure from chan&in& due to ibration#,Someone in the forum did this once# I for&et 'ho###2To tune it you1ll need a fuel pressure &au&e and a chassis dyno or a !tech unit#

$ou really don1t 'ant to do this by feel alone#The idea is to start from >< pressure and t'ea the thin& up a little bit at atime until performance peas# ,It1s a bit more inoled than I1m coerin& here#2:eep in mind that if you restrict fuel flo' too much you could burn out the fuelpump=