Thread: 2001 GP 3800 Wont Idle without gas pedal

like it says.. Every time i start this car it has very extended crank, when it does turnover it will not idle unless i keep it running myself. I have been trying to figure this out, any help would be appreciated. I have replaced the coil packs, new plugs, plug wires, fuel pressure reg, and map sensor. It has not resolved this issue. I did pull a vac hose and it does idle and runs great, but soon as i put the hose back on, the car dies instantly. Unplugging the IAC does not make a difference.

since the car wont stay on by itself or even turn on, and it only stays on when you either press pedal to give it more air or by pulling a vaccum line. It means that not enough air is getting into your engine. could be two things. you have a plugged up pcv valve or a bad IAC stuck in the extended position which means pintle is actually stuck on throttle body or carbon deposits on pintle causing it to be stuck not letting it open up to allow air into engine. 1. you can check pcv by removing it and shaking it. a good pcv will make a rattling sound. another way to check it is to see if you can actually blow air through it. 2. as far as the IAC, remove it and clean pintle with carb cleaner and also clean the hole where the pintle extends into (its about a 7/16 inch small hole. you can also check IAC by removing it but keeping it connected to harness and have a someone turn the key to the on position but not crank and see if the pintle moves. if it doesnt then that means the little motor inside of it is bad. Good luck

Originally Posted by Jakegday

which vacuum hose did you pull?

Its the vacuum hose on the back of the manifold, the one the that is next to the brake booster.

Originally Posted by chev1988rolet

since the car wont stay on by itself or even turn on, and it only stays on when you either press pedal to give it more air or by pulling a vaccum line. It means that not enough air is getting into your engine. could be two things. you have a plugged up pcv valve or a bad IAC stuck in the extended position which means pintle is actually stuck on throttle body or carbon deposits on pintle causing it to be stuck not letting it open up to allow air into engine. 1. you can check pcv by removing it and shaking it. a good pcv will make a rattling sound. another way to check it is to see if you can actually blow air through it. 2. as far as the IAC, remove it and clean pintle with carb cleaner and also clean the hole where the pintle extends into (its about a 7/16 inch small hole. you can also check IAC by removing it but keeping it connected to harness and have a someone turn the key to the on position but not crank and see if the pintle moves. if it doesnt then that means the little motor inside of it is bad. Good luck

Thanks for all of your help, i will check the PCV Valve, and check the IAC.

Originally Posted by FoSHO99

would go ahead and replace the vac lines. 26 bucks if a good cleaning of the iac doesn't work. Just because it idles without it doesn't rule a vac leak out.

Where is a good place purchase the Vac lines? Just Napa? Thanks!

Originally Posted by cerick08GP

Sounds to me like your fuel pump resistor is bad. I just don’t get the whole vacuum hose thing though.

Good luck

Is there a way to check the resistor? Where is the location? Thanks!

if it was fuel related then it would not start at all or stay on when you press the pedal. your giving it more air by pressing the pedal which achieves the correct air/fuel mixture to turn the engine on

Does that bypass only work for gtp's? I have a 97 gt doing the same thing.

You have a bad IAC solenoid, had it happen on three diff cars 5 times. It will not always set a SES light.

Okay, where exactly is it located? I will try changing it out. I did notice too that once the car sits for a while after it will start up.

I have came across this and found it to be the throttlw postion sensor. Actually ive came across this a few times. Check your codes if you have any. Either tps sensor or iac Sensor both located on your throttle body

Someone will correct me if I'm wrong but I think the 2 speed fuel pump is only on the GTP (supercharged) cars.
Rob

Originally Posted by Fritcr

Someone will correct me if I'm wrong but I think the 2 speed fuel pump is only on the GTP (supercharged) cars.
Rob

Yes, only on the GTP...

Okay so I changed my IAC valve, and it seemed to idle and run a lot better! Then I went to the store and when I came out, I had the same problem it would start then die immediately I had to keep the gas down to keep it running. Even then it was sputtering and a lot of smoke was coming outta the exhaust. I managed to start driving and I could put ti to the floor and it would sputter along at no more that 20mph.. I let off some and it sputtered up to about 30, then it seemed to clear up and ran fine again, I had all the power back all of a sudden... Stopped at a light and it was alright, I got on it some and it could break the wheels loose no problem...

I have changed the IAC and the cam shaft positioning sensor so far... This is driving me crazy since it will run fine one monent and not at all/barely the next...

Tps changed and I removed the EGR and cleaned it and put a new gasket on it... So I drive about 10 miles and go into the store about 5 mins later come out and start it up and it dies right away... I had to hold the gas down slightly to keep it running again.. I started driving down the road and it was sputtering real hard and then all of a sudden it cleared up again like usual and was fine the rest of the time... Stopped again got back in the car and it fired up no problems at all.. And its been fine on the last few times ive started it.. Just once in a while it seems it just wants to act up when I try to start it... ...???

Someone told me it might have something to do with the temperature control sensor?? Said that it might be sending incorrect temperature readings and causing not enough or too much fuel to be sent... Any comments on that???