Thread: need help ASAP PLEASE

Whats up guys, I know this is my first post on the forums but i have been cruising them since early last year. So i'm having some issue with the GTP and need some superoir insight as i am lost now.

Just a brief run down. I've popped a few codes as of late and they are Maf code (which is new within the month) and insuff. EGR flow (EGR valve as been replaced within the month as well and seafoamed the egr system while i was at it.) And also the O2 bank 1 sensor 2(rear one.) Still getting codes with new parts.

Now this is what the car is doing. when i'm driving down the road and i let off the gas to go into a turn or off ramp. the idle drops and bounces from 400 to 1000 rpms sometimes dying. Now this is a problem when doing 70 mph and you go to exit a highway, surprise, ZERO powersteering but when just sitting at an idle without the car moving it idles fine. I have also cleaned the ICV thinking that may help my issues but no. Also my MPG have dropped from around 21-22 to 16-17 during all this

I can live with a bouncing idle but not about smashing gaurdrails with my 2 year old daughter in the car.

i have started the car and while running unplugged the tps, map, and icv and none of them had any affect on how the car ran. Doesn't drop idle, change or studder at all. So i'm thinking i may have a bad driver in my PCM. is this possible???

I'd like to hear from some of the senior members on here or just a GTP guru. i have done alot of trouble shooting and just would like to get to the bottom of this. Thanks in advance for taking the time to read my long post guys.... T.J

I have a 99 GTP,

i have replaced the MAF but not the rear o2. i ran the seafoam through the gas and oil and yes the filter was changed. i've checked for vacuum leaks as well by spraying the vacuum lines and listening for the idle to raise. Nothing there. If it was a CPS wouldn't the car throw that code??

and just to be clear its not just the tach bouncing the engine is actually reving up and down

also could a bad cat cuz this behavior?? i had a bad spark plug for awhile just didn't know it and i'm sure alot of unburnt fuel when into the cat???

also i cant thank you guys enough for the very fast replies

Originally Posted by bluegtp91

Bad spark plug...was it damaged? If so then you have internal issues...if not then don't worry about it. Not sure if the CPS throws a code...never had any issues with mine. Cat...what cat? I'd get rid of it so you don't have to worry about it. Also...since yours is a '99...you might fuel pump issues...try bending the sensor tab seen here in this pic...

what exactly does putting the fuel pump in high mode do?? i mean sounds like more fuel output??? and yes i do want to get a down pipe to take the ubend and cat out. but wanted to try to fix this issue before and performance mods you know what i mean.

I will try this but on a side note I was just out messing. With the car and I unplugged the tps and the rpms jumped. But only that one time , couldn't get it to do it again. I also unplugged the maf and icv and no changes in idle. I'm confused a little

I was thinking that but was kinda waiting for that code. Plus i feel like I'm throwing parts at something that isn't the issue. But I guess I will try it. And the relay thing didn't work for me. Thanks for all your help so far

Originally Posted by 01GTP

Check the wiring going to the maf.

is this a common problem or just a suggestion?

i'll give it a shot. at this point anything is worth a shot. can a tps go bad and not throw any codes, but throw other codes instead? and can you tell me what some of the symthoms of a bad ICV

Ok , so I replaced the tps as well now. And still the bouncing idle. I've searched for a vacuum leak and can't find any. If I hook a boost gauge on it way should I be getting as a reading? And is this another valid way of checking for a leak

Where is the best place to tap into the vacuum line?