I have become involved in a coversion project that was begun,abandoned,then begun again.A ZZ4 crate motor was installed into an '89 RS which was originally equipped with a 5.7 TBI.
Once they got the car running with all the original induction and fuel systems intact.The idle quality is very bad,and the car is very nearly undrivable.
What do I need to do to fix this problem?

 

Your own chip burnning equiptment!

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Chronologically challenged. But still kicking!
'92 CAMARO RS
305 TBI 5/spd (now TPI)
B4C Alt.
Cam change:TRW 198/210 ,450/.460 114 LSA
Stock TBI manifolds
'85 IROC 3" Cat. back Exhaust
14.94-92.00 mph
SDPC base and "350" Vortec coming soon!
'69 camaro-BB/Lenco,1050 dominators, /Pump Gas/no drugs 8.97-150+/3200lbs.
SoCal Thirdgen F-Bodies

 

yah, he said it best.
but you can call hypertech and give them the specs of your engine(cam, heads etc etc) and they can proly burn a chip for you.
But for proly not to much more, you can just throw an intake and carb. on there, and you will make more power than the crappy tbi.

 

hate to say this,,,,but there was no 5.7 tbi. but if it is tbi,,,or tpi,,,is should be more flexible than you have stated.

 

are you running EVERYTHING stock that was previously on the car? throttle body, etc.?

you will definitely need a custom chip to get the most out of it, and i would DEFINITLEY get a high CFM throttle body if you plan on keeping the TBI.

but..even without a custom chip, the car should be more than driveable. i drove mine for over a year with a stock chip and it screamed. this spring i am going to be making/getting a custom chip, so i plan on seeing what the combo really has.

so, what are you running? what equipment?

-brian

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1991 Camaro RS
GMPP 350 HO crate engine - 454 TBI, MSD ignition, SLP exhaust, everything is new
700R4 - 2,400 stall converter, vette servo, shift kit
My car's webpage - z28boy.cz28.com
President - Central New York F-Body Association
Email - z28boy@twcny.rr.com
AIM - "Z28 Boy"

 

Maybe you should get a TBI from a
big 454 and then have a chip burned
for your car.Unless your running a TPI.
Just a thought.

 

Isn't there 5.7 TBI that exist in Caprice cars.

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'89 GTA 5.7 TPI bone-stock

 

yeah, and in trucks, but not F-bodies.

 

all the throttle bodies are basically the same, except the 454 truck throttle body has 2" bores instead of 1-11/16" bores.

the difference between the 305 and 350 throttle bodies is the rating of the injectors.

you can get an adaptor and get either a 454 truck throttle body or a holley 670 cfm throttle body. but, you shoudl probably use your injector pod (with either) because the GM style injectors are WAY better quality than the ones that come in the holley, and both the 454 tb and the holley come with HUGE injectors.

your best bet will be to use your stock injector pod, make the fuel pressure regulator adjustable, and use your stock injectors at a higher FP or get 350 injectors.

with the stock TB you will starve the engine for fuel. BUT it should be driveable. so that may not be yoru problem.

-brian

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1991 Camaro RS
GMPP 350 HO crate engine - Holley TB, MSD ignition, SLP exhaust, everything is new
700R4 - 2,400 stall converter, vette servo, shift kit
My car's webpage - z28boy.cz28.com
President - Central New York F-Body Association
Email - z28boy@twcny.rr.com
AIM - "Z28 Boy"

 

I replaced my TBI 305 with a crate 350, but not as agressive as the cam in the ZZ4.Still, You should be able to make it work with the 350 Truck injectors,adjustable fuel pressure regulator and a custom chip.
Mine puts out a little over 300HP with this setup,but with the Crane Compucam 2030 hydraulic roller,ported Turbo City Throttle Body and cast iron TPI heads.
With the ZZ4 cam, you might need the 454 injectors, but like Z28 boy said, I'd stay with the gm injectors as they will tolerate more fuel presure than the Holleys.
-Rich-

 

If you're running the TBI it's close enough to a regular carb. so I'd dump the TBI, ecm, etc and use a nice new 750 carb. That's just my opinion.

 

I agree. Drop the TBI and go carb. Obviously you aren't into EFI enough to understand how it works so give it to somebody that has lots of time on their hands.
EFI is only as good as it's programming and obviously you need some good programming.

 

If you want to stay TBI get the chip reprogrammed and get this
670 CFM 2-BBL GM Truck TBI
Made by Holley, "Fully compatible with all O.E. plug-ins" plugs right into your old harness