Hello everyone...

I bought a new to me 1992 Trans Am TPI Automatic... It dies when i put in gear I have to keep my foot on the gas to keep it running... it will idle at about 1k rpm and every couple of seconds it idles down to 700rpm more or less after a few minutes it dies starts again without a problem and will run for a few more minutes ... even if i rev the engine up to 2k it still every couple of seconds it drops 300 rpm and goes right back up to what it was before dropping....

It was running ok a couple of weeks ago but it would die when I stoped at a light for more than a few seconds... them it started with the problem I have now and eventually it died completely my mechanic told me it was the fuel pump and he replaced... nothing changed with the new pump other than the car starts again now...

Do you guys have any idea of what it could be?

Thank you!

 

Is there any codes it's throwing?

 

LB9GTA thanks for the reply... no codes I ordered a cable to link to my notebook I have not yet received it... but no check engine light...

 

Check the timing. Also how many miles on it? Mine was acting up a couple of years ago and I replaced the entire distributor.

 

A bad TPS will also cause this. Not hard to check the adjustment

 

Aaron thanks checking that now... I will post the results shortly!

 

I wouldn't throw any more parts at it until you're able to scan the car. Could be a whole host of things.

Are you planning to use tunerpro?

 

Aaron it was 0.53 I have it now @ .054 no change at all same problem...

Thank you!

 

ULTM8Z

Thank I agree...

Brian from http://www.tunedperformance.org recommended the following harness to connect to my PC http://www.moates.net/aldu1-and-cabl....html?cPath=64
I just received it a couple of hours ago...
He also recommended the TunerPro, I will try to pull the codes as soon as the rain stops :-(


Thank you again!

 

It has 105k miles, the distributor looks like new... the previous owner had replaced a bunch of the ignition parts and sensors.. so I this car had a few problems...

 

Yeah he's right. Its a good investment for future troubleshooting situations.

Record some running data too. Then post it here. We can take a look at it.

 

what cable / software will you be using for this? I need this too but have no idea where to start / what to get!

 

Cable
http://www.moates.net/aldu1-and-cabl....html?cPath=64

Software
http://www.tunerpro.net/downloadApp.htm

I have not yet used it... because my battery cables are really bad I bought new ones and they have not arrived yet... I think this could be one of the problems I have... they are corroded and green inside I cut as far back as I was able and the green still shows up...

The cable looks to be really high quality

 

wow the software is freeeeeee so you just need the cable?...sweet!!!

 

I read a tech article from some TPI guru awhile back that stated bad battery cables can wreak havoc on the TPI cars and is often overlooked. Might cure your issue, the info I mentioned is near the bottom.

https://www.hotrod.com/articles/1985...tte-ses-light/

 

Clogged cat will do weird things. Unbolt it and see how it runs disconnected. I edited this to add another thing to check, rent or borrow a fuel pressure gauge. Your fuel pressure regulator may be on the fritz. My GTAs went out and I ended up buying a Holley adjustable unit.

 

Thank you Reddragon88gta, I had to replace all the battery cables they were really bad, but no luck the problem still the same...

 

Thank you BigWhiteGTP my car has no CAT and it also has long tube headers...

 

Hello everyone..

I just got my ODB1 plug fixed and got my Moates adapter to work with the car to read data... the only thing it shows in red is the Target AFR @ 14.28
I am going to post the log and the ADX file I used here.. I took the car back to my mechanic that installed a new fuel pump and he is now telling me that I need new injectors without even looking at the car..

Thanks again for all the replies and suggestions to fix this problem!

 

Here is a screenshot of the data

 

He was selling the car, I'm sure he/she would have told you that they did a fresh tune up the day prior if it makes the sale. Start with a fresh tune up: new plugs, wires, cap & rotor, etc.


Where is the O2 sensor located? If it is down by the collector, that is farther from the heads than the stock manifolds. The distance and exhaust flow makes it harder for the O2 sensor to stay heated and give proper readings. It might be worth investing in a heated O2 sensor

 

Thank you blacksunshine,

I replaced the cap / rotor cables and spark plugs already.and the coil as well.. I will check the oxygen sensor location tomorrow.

 

Thank you Blacksunshine'91

The o2 sensor is next to the oil filter on the driver's side before the collector. :-(

I tried to follow all the vacuum lines and one of the hard lines that go under the TPI intake (connected to the front of the driver's side close to the throttle body is broken and missing part of it... do you know where it should be connected to?

 

When you are looking at TunerPro, does your car continually switch between Open and Closes loop? If so, I would bet that your O2 sensor isn't staying hot enough. A heated sensor is actually pretty easy to hook up.

If the hard line is the one I thinking about, the forward end connects to the nipple on the bottom of the throttle body. The other end of the hard plastic vacuum line attaches to the EGR solenoid. Another hard vacuum line should then go from the EGR solenoid to the EGR valve.

 

Here's a thread that shows where the lines should be.

https://www.thirdgen.org/forums/tpi/...-solenoid.html