I've got a '00 M6 SS, and I've got this ridiculous TPS problem that I CAN NOT figure out! It started a while back and slowly got worse and worse it seems like. I'll be driving the car down the road and when I push in the clutch, my rpm's shoot up to around 1800 or so and just hang there for a few seconds before it slowly starts idling down to normal. It does this between shifting gears and when I'm pushing in the clutch to come to a stop. Here's the weird part...say I come to a stop, and if I let the car idle down to normal (750-800) rpm's and then I take off again...the car acts perfectly normal... no "high-idling" between shifting gears OR when I'm coming to a stop. But, if I don't let the car settle back down to normal idle all the way, the problem persists.

Here's what I've tried: Replaced the TPS with no luck. Tried different throttle bodies with no luck, and I just replaced the TPS wiring harness/plug with no luck. I soldered the new TPS harness/plug in last night and let it reset before start up. When I started the car, it idled real high and funny for a few seconds and then settled down. I drove it down the road and it drove perfect! During my drive, I shut the car off at a stop light and restarted it and it instantly started idling and driving bad again...with the same problems as before. It's like if I let the TPS reset it'll drive fine, with the exception of a weird start up idle. I have no more ideas!

A friend of mine told me I may need to replace to Operating System. Anyone have any input on that? I'm at a loss right now. Any help would be extrememly appreciated! And sorry for the looonnngggg post!

 

you might wanna see if a friend has a IAC you could swap out and possibly your maf too. Is it throwing any codes?

 

Without knowing if you have any mods or not.........I'm gonna say a sticking IAC motor. It can't react fast enough and when you sit at a stop for a bit then its stuck on the low idle side instead of high. Try cleaning or replacing the IAC and see how it is. If you're modded and tuned it can be a whole lot of things.........

 

Thanks for the responses! Well, I just installed H/C/I, 42lb injectors and other supporting mods...but the car had already been acting up like this before all that work was done. So, it shouldn't have anything to do with the mods or tune. Here's where it gets even more weird! You both mentioned changing the IAC sensor out...I have tried a total of 4 different throttle bodies on my car. The first one was a ported TB, and I changed that one out with a buddy who had a stock one on his car. With his TB on my car, it drove perfect! Not one problem! With my ported TB on his car, it drove perfect for about 500 miles and then it started doing the same thing on his car. We swapped them back and his car was back to normal and mine went back to screwing up. I traded my ported TB out with two more stock ones. After the install of those two throttle bodies, on the first drive, my car drove great. BUT, the very next time I went to drive my car, it was acting screwy again. It's like I "tricked" the PCM for the first drive, but after that one time, it knew what was going on.

About a CEL. Every once in a while I'll get a code for the TPS. I can't remember the actual code number though. It's weird, cause the light will be on a while and then out of nowhere, it will go off. Hope this all made sense.

 

sounds like a leaking evap solenoid, could be a leaking brake booster. could be in the tune. could be a sticking cruise control assembly. your tune could have something to do with it, decay problem, your iac steps.... endless possibilities with the given info. when you changed throttle bodies did you change iacs or keep your same one. i would go for iac at this point.....

 

A datalog of the drive and the resulting problem would help.....

 

When I changed throttle bodies, they had different sensors on them...so I'm kind of ruling out the IAC because the cars the "test" TB's came off of worked and drove fine. I do have a buddy who has HP Tuners, so I'll see if maybe he wouldn't mind taking a look and hooking up his software to my car and get some more details of my cars operation. Thanks again for your suggestions and ideas. I'll definitely keep things updated here. I'm going to be swapping out my TB again today with the one that was working on my car a while back. So, we'll see!

 

Update: Swapped TB's again with the one that worked on my car a while back (the one I mentioned earlier) and it was even more screwy than ever. My buddies car that I swapped with was doing the same thing as mine was, so we were thinking maybe all 3 of the TB's I had tried were messed up. That's the kind of luck I'm having, so it wouldn't surprise me. His TB on my car started and idled great and drove great the first few minutes. After a few minutes of driving it started screwing up again, but not bad. I pulled in my driveway and let the car idle for 5 or so minutes and jumped back in to drive it and instead of high idling, the car would drop to like 2-300 rpm. Did this for a few minutes...I pulled to a stop light, shut the car off and when I restarted it it drove perfect. I pulled to another stop light, shut it off, when I restarted it this time, it was back to the high idling problem.

I'm going to try running new wiring for the TPS all the way to the PCM and seeing what that does. Just another update on my piece! Thanks!

 

If that doesn't fix it Joe we can pull a log of it while it's happening to post up.

 

Alright man. I found that schematic you were talking about, so I'll be able to look at that tomorrow. Thanks for the help

 

Good luck Joe!!!

 

Hate my car. Just to make sure there were no damaged wires, I ran new wires from the TPS to my PCM, and that did absolutely no good. Still having the same problems. What are the chances of the actual PCM going bad? Should I try datalogging before anything else?

 

What is your tps voltage closed throttle? Should be close to .6 volts

 

Ill get a log of the car and post it up in the next few days.

 

Last time I checked it was at .3 volts. But, while the car was sitting, I bumped the throttle and the voltage dropped to 0 and stayed there while it idled down.

Bill, just let me know when you're free...I'll work around your schedule.

 

Last I checked, the tps voltage was at .3 volts at normal idle. But, when I bumped the gas the voltage actually dropped to 0 volts and stayed there while it slooowly idled down.

Bill, thanks so much. Just let me know whenever you're free...I'll work around your schedule.

Oops, stupid internet connection!

 

Just give me a call