The car starts up fine and runs smooth for the most part. I can drive it okay, but as soon as I get on the gas (2/3-full throttle or sudden acceleration) the rpms fall off and the car doesnt move. The tach falls to about 700 and just sits there. This is a big problem in traffic. Then if I let off and slowly go back into the gas, the car will move. But sometimes it'll only rev to a certain point, no matter the position of the pedal.

There is a hissing as the car runs, I think it might be the IAC. But I really dont know since I have very limited experience with this.

I forgot to mention: 1989 stock GTA with 350 TPI

 

the hissing sound might be a vacuum leak from a broken or missing hose.

as for other things that could cause that hesitation/rpm limiting problems, i've seen similar effects from crappy ignition systems (mine, didn't like to go over 2200 rpm), clogged fuel filter, and it also seemed to drive better overall after i replaced my O2 sensor.

i've never had a bad IAC, so i can't speak for that though

 

I checked all the hoses, and they seem to be ok.

Now, here is the interesting part: Last summer, the car started acting the same way. It would go nowhere under full throttle and would lope at idle. Within about a week or so, I couldn't start it up and let it idle because the lope was so bad that it would die out. I would have to give it 1/2 pedal just to keep it running. It sounded like I had a killer cam , but from the outside it looked like I had a manual and didnt know how to drive (because of the shaking).
I read the engine codes and it gave me a TPS code (44 if I remeber correctly ). I talked to a few people and they suggested replacing th O2 sensor, because it was cheaper than TPS. I replace the O2 sensor and the car ran like new. I was happy...until now.
Could there be something thats burnin out the O2, or is it some other problem? Any advice would be appreciated.

One last thought: A friend and TPI guru told me that the car should stay running using input from the TPS if I disconnect the MAF. It doesn't. Are all these problems related?

 

some cars have a default setting for the MAF signal, others move to one extreme or the other (very rich or very lean) since the car thinks it gets either zero or infinite air. so i'm not sure i'd recommend removing it on an '89. the older ones might have ignored it, but the 88 i had couldn't.

you can try having someone start it and revving it by pulling the TPS manually to see if it seems to be a problem. (you can alternatively squeeze the cruise control servo for the same effect)

i'd do the fuel filter just in case, it's like a $5 part and takes 10 minutes to change (just make sure you cover the fittings with rags to catch the 40psi gas that can spray out)

might want to look for a junkyard TPS or borrow one to test with if you think it's too expensive to get a new one. or try another O2 sensor, it's just $25 or so

 

and like i said, i never did much with the IAC, but i don't think it should really affect the high-rpm performance

i'd check all your wires, and maybe the plugs & distributor too, and make sure the O2 sensor wasn't all fouled when you take it out.

 

Thanks a lot. Tomorrow (hopefully) I will check the fuel filter. This makes more sense to me now, because the car acts like it would if it were running out of gas. I'll try to keep you posted. Thanks again for the help. I had no idea what to do.

Dave

 

well, i can't guarantee these will fix it, but they certainly helped when i had that problem. just be careful with all the high pressure gas that will come out when you disconnect the fittings, and put some plastic bags/sheets down and something to soak it up, or it'll be all over the place.

 

when you replace the gas filter
REMOVE the gas cap it will relieve the pressure of the fuel line so you wont have gas spraying all over lol 1 other thought i had the same problem with A different kind of car ..... it could be a fuel pump going bad i also own a 89 gta 350 and if thats the case i hope not your looking at alot of work just to get to the gas tank

 

The problem turned out to be the MAF sensor. I disconnected the MAF and the car ran strong but rich. Now the question is, where can I get a MAF for relatively cheap. I dont have $150 to buy a new one. If anyone has any suggestions or has been here before, post up.

Thanks for all the help,

Dave