Hey guys, I'm usually over on the thirdgen site with my 88 Camaro, but I've been having trouble with my 4th gen car too and through all the searching and diagnosing I've been doing I'm at a dead end. For awhile now the car will throw a multiple misfire code and go into limp mode. It happens at idle when warm, all of a sudden it's like a switch is flipped and the car starts stumbling. When you restart you can tell the idle won't hold steady, but bounces around where it should be steady. It'll run like that and then go into limpy stumble mode. Wait a bit for the car to cool off and it fires right back up just fine. I even drove around running errands the other day after throwing on new plugs and wires, starts stops and restarts, car ran fine. Started the misfiring as soon as I got home and popped the hood to double check if I missed anything. I've checked all vacuum lines, the first time I found one that was chewed thru and fixed it, ran fine for awhile and now it's back. Checked all lines again, they're fine. Checked ignition, all coil packs fire the same and were still firing fine when the misfire started, so I'm not expecting ignition trouble. But like I said, I'm at a loss, hahaha

Where should I go from here? ICM? MAF? Any advice is appreciated.

 

is that the only code

 

Ran the codes today- P1516 - TAC issues. Looks like it's common on 3800s and throws the car into limp mode. Also explains why the throttle occasionally sounds like it's full of marbles. Hitting the junkyard tomorrow....

 

Replaced the entire throttle body with a clean one off a nice junkyard car, didn't help the problem very much. Now the car dies a few seconds after you start it up, then restarts and runs fine. Going down the road the other day the car just straight up died and said CHECK GAUGES-no SES light. Had just fueled up, too. pulled to the side and fired right back up. You can almost tell there's a delay from touching the throttle and the car responding, like they're still not in sync. Guess my next move is to just trace the rest of the electronic throttle system....

 

sensor at the foot peddle may be failing. i have not had the pleasure of having to deal with tac yet.

 

Thanks for the input, craby. I Replaced the accelerator pedal sensor/assembly, Camaro's still acting up. There's like a 1 second delay between hitting the throttle and the car responding. Whatever's failing is heat related, the car fires up fine cold but when warm, it can't restart withing dying right out. You have to start and hold the throttle at about 2k RPM for a bit to get the car to run when warm. Let the car sit for a bit and she fired up, stumbling, but idled. What to check now?? Gotta find a diagram for this throttle system somewhere.....

 

go here http://www.mediafire.com/?40mfgeoe4ctti and download the factory service/shop manual, 2000 svcman would be for your 2000. what is the temp gauge reading? is it working good?

 

Just the heads up, one of the main problems with the Throttle bodies is a lack of sealing in the throttle shafts. The throttle shaft leads right to the optical sensor. The fastest way to kill the throttle body is to spray cleaner into it and its almost guaranteed to ruin it is the engine is not running when you spray it. The cleaner runs right down the shaft and in to the optics. but it should be throwing the code for DBW

IMO its a bad design because a single backfire can scrap it.

On the other side, in my 96 the MAF pigtail connector went bad, it is such a common issue now that make parts store have tem in stock. I was talking to one of my old mechanic friends and he said at his shop any car getting a MAF sensor more then 10 years old gets a new connector just because they fail so often.

 

Thanks everyone so much, I got it figured out! the misfiring/reduced power was solved when I replaced the throttle body. The car wouldn't restart because of something really silly- oil pressure. The car drove fine and idled great driving around all day, the only trouble was I had to give it some throttle when restarting. To build oil pressure! The gauge started reading low, it hit me the car was stalling because the oil pressure switch wasn't letting the fuel pump stay running. Just changed and refilled oil, drove around great and pulled over every few miles to try restarting. No problems! Thanks all!!

 

pick up a new oil pressure switch/sensor, sounds like its not happy. may be ready to go or could have some old oil in it gumming it up. just had mine fail in the 2k and it ran fine with the gauge at 0, check gauge light came on. it was leaking oil pretty bad out of the sensor itself.