1997 Gtp Running Funny

**DanGTP** · 11-09-2009

Sounds like what you unplugged was the intake air temperature (IAT) sensor. The MAF is the one on the top side of the throttle body with a 3-wire plug. The "vac leak" sound you hear when it bogs is probably the idle air control (IAC) valve opening trying to bring the idle back up. Does it sound like a vacuum cleaner when it does that?

**chi_town** · 11-10-2009

Hmm im not sure about a vac cleaner, you can just hear a vac leak period as it struggles to stay running, but even when i have the IAT unplugged it still runs alittle bad =( , after the engine went it hasn't ran the same with the newsed one and it's making me hate the car and not even able to enjoy it ...

All i know is the mpg is horrible for the car, and all i have done is a 3" dp and k&N drop in , that's it.. But the mpg was horrible befor the o2 was taken out so idk whats the issue... =/

other than what is stated is has lack luster power ..

ideas?

Chi_Town

**DanGTP** · 11-10-2009

I'm a bit stumped. Do you have a way to get a video of it 'running'?

**MONTEMATTMAN** · 11-14-2009

I have a 99, it does about the same thing. Runs rough and is hard to start cold, hisses out the air intake, sometimes dies out like it's running out of gas and so on. I have replaced the fuel pump and the MAF with a new one, but it still puts the MAF code. I have replaced the plug on the MAF also, but to no avail. The car runs great other than being coldnatured, and it actually hasn't died out for awhile now. The SES light stays on constantly with the MAF code, but unplugging the MAF makes no difference. If you figure something out, let me know. Otherwise, I love the car.

**chi_town** · 01-18-2010

Still no fix, a friend told me that the codes i brought up like stated befor are just a universal code and should'nt be followed. So i went ahead and looked around online for those codes that would be brought up for "GM CARS" and found myself looking at a "MAP" sensor being the factor here.. I ordered one just now and will get it tommorow, i still belive i have another sensor from the old engine sitting at my house so i may toss that one on there and see what comes of it, if that fix's the problem then i wont be needing the new one.

I was going to get a few things done to the car but that will be put on hold untill i get this issue fixed and move forward with valve cover work and wheel bearing.

Any other ideas?

Chi_town

**gtpinsc** · 01-18-2010

MAP sensors dont commonly go bad on these cars... have u checked ALL vac lines for leaks?

**blueguy** · 01-19-2010

Hiss is a vacuum leak. Check all the "T" fittings around the blower and from the TB to the black canister on the back of the blower. Either that...or it needs new plugs/wires/coils/ICM.

**chi_town** · 01-19-2010

Plugs,wires where just changed and the coils where swapped around and changed out with another set, still same thing. It just seems like i have to almost continue to push the gas at start up to keep it running like it's running out of gas or somthing, which than makes it sound like a vac .... But when it clears up, it runs fine... and seems to boost normal and have good power. Thats where im so confused, because if there were a vac leak wouldn't it be there constantly? not just at startup or some times at idle?

Chi_Town

**BigTom73** · 01-19-2010

I've got a couple of questions. Did this problem start after you dropped the new engine in? What year GTP did that engine come from?

**blueguy** · 01-19-2010

Diagnosing a car without video is stupid for the most part...get a vid man...it'll help a ton.

**DanGTP** · 01-19-2010

Originally Posted by chi_town

Thats where im so confused, because if there were a vac leak wouldn't it be there constantly? not just at startup or some times at idle?
Chi_Town

If you have a gasket leaking on the TB/SC/Intake, it may clear up enough to not be noticeable once things get warm and the gasket and metal engine parts expand a bit. Start off by checking the TB gasket. New ones are only ~$5 at Auto Zone. Go ahead and replace it if the old one is questionable or tears when you remove the TB.

I recently did some trouble shooting on a friend's car that acted like there was a huge vac leak, but it made absolutely no hissing sound. We swapped in a new MAF just to be safe, but there was no change. Got out a can of ether and started spraying. Found the leak at the TB gasket. Turns out the TB gasket had been put on backward and had just recently started to leak enough to cause problems.

**chi_town** · 01-21-2010

But as of late it has been doing it as im driving as well.. Usually right when im at a stop I'll go to hit the gas , and it will start to sputter almost like it's running out of gas. And, under boost or on highway if i only go about .25throttle it starts to jurk and the rpm's jump...

Im getting tierd of putting money into the car, when I even brought it to a shop and they didn't find anything... idk how they couldn't find naything though.

it's still pulling the codes listed earlier in this thread and even when i delete them they come right back. Sounds like i have a HUGE vac leak somwhere then it goes away and does it from time to time at stops and while I hit the gas to pass it surges....

Chi_Town

**DanGTP** · 01-21-2010

Grab yourself a can of ether and start spraying around all of the gaskets you can get to.

**caput0** · 05-15-2010

same problem here. except my car will only run for about 5 secs nd then dies out.. seems to be starvin for gas?? its weird. just started this problem yesterday while drivein.

ANNYYY HELPPPP IS APPERICATED!!