RocketScientist

1991 Pontiac Trans Am GTA 5.7 TPI, 5 speed. Recently bought this car from a guy out here in Colorado Springs. States it was "built" in N. Carolina with oversize injectors. (40lb?) Looks like 24lb is recommended for our elevation. Car runs rough & wont idle at all after warm. Smells extremely rich.

Big&BadGTA

iTrader: (1)

How was it "built"?

A 5.7L uses 22b injectors from the factory.

Tuned Performance

iTrader: (92)

I’d use 22#hr injectors. The ecm should be tuned for the 350 swap or maybe it was a trans swap.
The letters on the computer chip (memcal) will tell the story.

RocketScientist

It was a 350 TPI motor pulled from an 87 Iroc. Guy said it was decked & bored .30 over, heads resurfaced & rebuilt. Not real hip to the TPI jive. Don't believe it was chipped or tuned afterward. He did say the injectors are bigger than stock & it ran great at sea level. Up here its pushing way too much fuel. Really rich.

Big&BadGTA

iTrader: (1)

When I drive to Colorado, I don't change my injectors.

Again, 22lbs on 350 is factory. Unless a bunch of other mods, that's what I'd go with.

RocketScientist

Thanks. Looks like Ill be shopping for 22lbs set.

RocketScientist

Are the reman sets on EBay decent? Bosch etc?

southbay08

Tuned Performance

iTrader: (92)

You might want to verify it’s a 350 not a 305.
Block I’d behind the drivers side head. Suffix code rh front of engine bye tha a/c compressor if equipped.
Then contact southbay. They might cost more than eBay but you know they will fit.
And if you have any issues they stand behind there products.

RocketScientist

The former owner said "he" built it. The car originally came with a 305 TPI (5 speed T-Top car) & he pulled a 350 TPI motor out of an '87 Iroc with an auto. He told me it has 40lb injectors in it, hense the rich condition & poor idle issue. I know they didn't put a 350 in a t-top car with the 5 speed. Structural issue my guess. 350 TPI models w/ 5spd were only hardtops. Plans moving forward are to put the stock 22lb injectors back in, & have a look at the current "chip" to see if its been modified (Hypertech or whatnot) & go from there. Do I seem to be on the right track here? Thanks for all the responses. Its just going to be a daily beater. Its kinda rough around the edges.

Big&BadGTA

iTrader: (1)

40lb injectors. Not good. Not even at sea level.

I'd have to think back to my 383 and recall. But 26 lb injectors, maybe.

Anyways, good luck!!

Tuned Performance

iTrader: (92)

Your on the right track, if you Post the letters on the memcal I can identify it for you.
There wouldn’t be a Hypertech that would be for that application. It would be a custom tune.
http://www.3rdgenformula.com/87/promcodes.htm
No doing a tune might result in idle surge on deceleration. A 305 memcal controlling 22#hr injector will also run rich.
http://www.chevythunder.com/prom_bcc_1987.htm
If you have tpi maf these codes would apply.
I’m thinking he left the stock speed density setup and 1227730 ecm in place.
If that the case you would have a ATNX,
AWFZ,AXXC, AXXD
ANJS,
ANJJ,
AXYC
You might want to install a new o2 sensor when you swap injectors. It might be fouled from the excessive fuel. You can identify the injectors bye the numbers on the body of the injector.
https://www.southbayfuelinjectors.co...0_TPi_i_1.html

RocketScientist

Well. Things are getting interesting. I tried to ID the casting # on the block but have to do it with better light. The label on the hood states it is a 5.7 TPI car. Unless the hood is different. I also thought the 91 models came with an HEI distributor? This one is fed off an external coil (looks to be a factory one) & is just laying loose next to the distributor. Great. If it was a 5 speed swap, it looks to have been done pretty well. Nothing out of the ordinary, like chopping or rough cutting anywhere. Car looks to be more of a basket case at this point.

Big&BadGTA

iTrader: (1)

F body used external coil / small cap.
Sounds fun.

RocketScientist

Oh..its a runner all right. Test drive the PO put it sideways across 2 lanes. Its definitely rough around the edges, & runs extremely rich with a non existent idle. But its loud & obnoxious. I like it.

Tuned Performance

iTrader: (92)

You might want to be gentle on that transmission if it’s a 5 speed.
It’s a gernade !

RocketScientist

Ive decided to hold off on the GTA for a bit & focus more on my 2nd gen Camaro project. Im up to 7 cars right now & looking to sell 2 soon. Ill probably get it in the shop in a few months to really start checking it out to become my daily. If I can iron out all the issues with it.