Can anyone in Freehold help someone out with a TBI car?
 

Ive been trying to help Mike diagnose his car over AIM, but its hard not being there in person. Its an 89 TA with TBI, and a 350 swapped in. Im so busy that I wont be able to make it up there any time soon, and was wondering if anyone around that area might be able to stop by and lend him a hand?

Some people are trying to steer him wrong with his car, and Id rather not see that happen... I told him to register here, his user name is 12gauge. If anyone is in the area and has some free time, that would be really cool. He should be posting in here shortly.

Thanks! :bow:

whats wrong with the car?

Hey everyone. Just wanted to say thanks to Rob for helping me out here- I really appreciate it. Well, my names Mike. I'm 17, and I just bought this Trans Am from a guy in Avenell maybe a month or two ago. Its an 89 Trans Am, and I'm having some trouble with it that I hope you all can help me with. The car originally had a 305 in it, but the previous owner swapped it for a 350 with an oversized cam and edelbrock intake manifold and throttle body system. He replaced some of the electrical engine components as well, such as the distributor and thermostat. When I start the car, it goes to 1000 RPM, comes back down to about 500, then fluctuates in between the two for a couple seconds before it stalls out. If I depress the gas pedal to a certain point and keep it there, it will stay at a steady 1000 or little lower RPM. However, when I let it go, it stalls out immediately. Also, when I keep it at 1000 RPM for a couple of minutes, my catalytic converter starts to turn red hot (towards the back end where it meets the exhaust pipe) and smokes (not out of the pipes, but its just so hot that it smokes). I thought it was backed up, but when I place my hand at the end of the exhaust pipe (I have the muffler off so I'm dealing with the pipe directly from the cat) I'm feeling the exhaust flow. I had a friend look at it, and he told me that the combination of things on the engine were no good (I was told the air pump was eliminated, theres no intake temp sensor, the cam isn't good for it, and I'd need to change the entire fuel delivery system among a couple of other things I can't recall at the moment) If anyone would like to give a word, I would greatly appreciate it. Thanks!

well more then likely the engine is running very lean to get the cat that hot,but on the other hand it is possible for an engine to run overly rich,and once the cat gets hot enough to burn off the extra fuel in the ex,it pretty much turns into a furnace.any chance u get black smoke out of the pipes when the car is running?

you didnt make any mention of a fuel pressure regulator, so I'm going to assume you're running the same PSI that you were with the stock 305. If thats the case, you're gonna be running pretty lean because a cammed 350 is going to need a lot more fuel than a stock 305. I would look towards the fuel system first to try and fix this problem. Try getting new injectors and an adjustable fuel pressure regulator because it sounds to me like you're motor is running lean.

it sounds like your car is running really lean and you need to get larger injectors if your running the stock 305 injectors, along with possibly making your fuel pressure regulator adjustable... also with a cam (which im assuming you dont know the specs of) you will need a tune to make the car run right... the stock ECM will absolutely not handle the cam and demands that the new engine needs... as for anything else... you have to tackle one thing at a time so you first need to address the fuel issue before diagnosing anything else

The cam thats in there is VERY small, on the line of almost stock small. And yeah, chances are he still has 305 injectors on there as well... forgot about those.

are all vacuum lines in good condition, any crossed? plug wires crossed? I mean it can be a multitude of things... if the cam is small, then the chances of the ECM being messed up a lot are not very good, a small cam like an l98 or lt1 cam will need tuning but it wont cause the car not to run, the injectors should be "alright" depending on the size of the cam but at idle theres not a high demand for fuel that would cause the injectors to go static... i would check some basic stuff first

Is it throwing C/E lights? The RPM flucuation is odd.

Just listening to that description I'd guess a vac leak somewhere, running lean.

Also, I might have missed it but has anyone address the tuning..ie the chip?

EDIT: Nevermind, I should read better, screw my idea on the chip, it's been addressed lol

Happened to me. too


first things first.

are all the spark plug wires on and on the right spark plug?

if so check the spark plugs and possibly change them and wires. if that doesnt work, check the oil to see how dirty it is and change the oil and filter.

if thats not it, it might be the cat because mine was clogged and did the same thing.

this is what I did and my car ran perfectly.

Yup, I did an oil change and my car gained 17 horsepower and started running great!

;):D

its the simple things we all forget.

my car wouldnt idle, wouldnt peel out(when it did idle)

after plugs and a oil change I peeled out of my garage

Reverse doesent count.

SOrry I haven't said much- I've been checking things. As it stands, the oil is fine- brand new oil, and filled to the proper point. The spark plugs are correct, and still in good shape. In addition, the wires to my knowledge are correct as well. As for vacuum leaks, there are none that I, my stepfather, or a couple friends I had look at the car can find. In reference to the injectors, they should be fine- took them from a 350 throttle body. Theyre not in GREAT shape, but I wouldn't expect replacing them to fix the problem. I threw a 350 PROM chip in there, so shouldn't that take care of the computer aspect of the problem? I had it programmed to all the engine and cam specs. Finally, the cat shouldn't be clogged up, because I feel the exhaust coming out of it. Can anyone come and look at it? I would greatly appreciate it, and thanks for all the suggestions here! Learning more each day ;)

I think the oil is the least of your worries ;) I was just messing with wayfast...he made it sound like an oil change made his car ran great.

it does, only for a few minutes though ..... :grin:

Moving this to the tech section.....

Who did the chip tuning for you?

- Justin

if you need chip tuning, i tune TBI's so PM me if your interested in finding out about a custom tune & pricing

A guy by the name of Brian from TBIChips.com did the chip for me. I gave him all the specs and he supposedly tuned the chip to it all.

its not going to be a perfect match for your car its basically what he thinks that the car will run well with... it is not based on any engine data so your not even close to running at your full potential yet

Listen to him hes tuning my car come Sept :D

Could it be possible that the chip is the main reason the car isn't running correctly?

have you definitely ruled out the catalytic converter? id address mechanical problems before thinking that its something in the tune thats haywire

The things that have lead me away from the cat are that I can feel the exhaust flow from it, and theres no real bad smell coming from it. Is there anything else I can check for?