Intermittent high idle after tune.
Thread Starter
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Joined: Jan 2010
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From: Hurley, VA
Intermittent high idle after tune. Occasionally my car will start idling around 1600 rpm then once it's stopped it gradually goes back down and acts normally. It did this twice on a 4 hour trip home. It made it 90 percent of the trip fine so I wouldn't think it's tune related. I'll check it out tomorrow for vaccumm leaks but since it doesn't do it all the time can it be the cracker table ?
I have the exact same issue. My car is a M6. Driving the car it is completely fine no issues. But when sitting parked at idle if you tap the throttle it will hang around 1600rpm or so and then slowly return to idle. I'm not sure if it's my iac counts or in the throttle cracker, or even what the issue is. I am positive it's not a vacuum leak but I am going to have to check again.
TECH Fanatic
Joined: Jun 2007
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From: Dolla$ , TX
Occasionally my car will start idling around 1600 rpm then once it's stopped it gradually goes back down and acts normally. It did this twice on a 4 hour trip home. It made it 90 percent of the trip fine so I wouldn't think it's tune related. I'll check it out tomorrow for vaccumm leaks but since it doesn't do it all the time can it be the cracker table ?
I had a car that appeared to do this randomly , it was a leaking Fuel pressure regulator causing random surges was a 97 cadillac eldorado
On The Tree
Joined: Oct 2011
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From: 20 minutes from the Valley...
It sounds like an IAC issue. When we were tuning my car the same thing happened. It would intermittently hold around 2k rpm in gear and pull the car down the road. If i put in the clutch and stopped it would slowly return to idle. Not 100% sure what my tuner did, but he messed with IAC settings and straightened it out in about 15 mins.
In my case it was something in the min airflow tables. But it has been there, it didn't just start one day. I could actually see the ecu command higher iac count keeping it higher than it should have been.
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It could also be the throttle cracker/follower decay tables are set too low and take too much time to come down.
If more air was added to the tune, the decay tables need to be increased also.
Brad
If more air was added to the tune, the decay tables need to be increased also.
Brad
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Joined: Jan 2010
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From: Hurley, VA
It doesn't do it consistently. It'll be fine 80 percent of a trip and then all of the sudden it will do it. I can be driving 50 mph and just throw the clutch in. It'll maintain 1600 until the car rolls to a stop. It never returns to idle when the cars in motion. As soon as it stops 3 seconds later. Idle drops to normal.
Thread Starter
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Joined: Jan 2010
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From: Hurley, VA
Ok the car got to the point it would hang every single time I moved the car. Sitting still it was fine. 2mph instantly 1600 rpm. I replaced the tps and swapped iac and as soon as the car started it would shoot to 1600 rpm. Thinking since the iac was a used one it was bad. So i put my original one back on I had the same problem. So I knew then the new tps had to have something to do with it. I hooked a scan tool to it and it was showing 23 percent throttle position. Loosen the screws up and it drops back to zero and the idle went to normal. Replaced that tps with another new one (same brand and it did the exact same thing). I took it off and put a old 150k mile one off of a throttle body I had laying around and it drives normally 90 percent of the time. I'm thinking my 102 tb is bottoming the sensors out inside themselves causing it to read a higher throttle posisiton at random times. The idle has literally hung once since putting the old tps on it. Now I have to force the car through the reverse lockout so I'm thinking I may have a speed sensor or a solenoid going out but my problem I believe is in the tps.