2000 Buick LeSabre. Still having a high idle after warm up. Have checked PCV, IAC, EGR valves for excess air. So far, nothing. No other vacuum leaks either. Put my scanner on to check IAC operation. When I manually dial it down, the idle is fine. Restart the car and it goes back up 100 RPM over what it should be (1000 RPM when it should be 880-900). Throttle body was cleaned also. Plate is where it should be without any hang up due to carbon buildup.

Could this be a software issue with the vehicle computer?

TPS?

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

TPS was replaced some time ago. I checked it again this week and it is where it needs to be. Idle still high even when it is removed.

Can you do a resistance reading on it and then move it and get an increase in resistance? What do you get when you have the key on, but not running when you read the voltage from the black lead to the other two on the plug?

TPS turned out to be the problem. Replaced and now idle is fine. One remaining issue. When idle is at 1100-1200, shifting transmission into gear results in a "slamming lurch." Doesn't happen when idle is 1000 or below. The car, which we've owned since new, didn't do this until recently. My 98 Bonne and 07 Lucerne don't exhibit this problem.

Any ideas?

Idle should never be 1100-1200 unless cold. 600-700 is normal. Are you sure the TPS was installed correctly?

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

Good to hear the 1st problem is fixed, the second problem could very well be a bad front engine mount.

I should have clarified my earlier statement. Idle starts at 1200-1300 cold, then drops to 600-700 when warm. Matches the desired idle indicated by my scanner.

I will check out the motor mounts. Like I said, car didn't shift so roughly a few months ago.

Yes, front motor mount (actually a transmission mount) is bad. Thanks for the suggestion.