Truck idling high too high and trans not shifting right
11-25-2009, 12:42 PM
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Truck idling high too high and trans not shifting right
I have a 99 silverado 5.3 with the 4l60e trans. Stock internals just magnaflow exaust cai no cats. It will idle and shift fine but after a while the idle goes up to 700rpms in gear and 1000 at park. The trans wont shift right, it hangs gears and wont shift till i let off. Does the tps control shifting in these trucks? Could it be a IAC problem or a transmission problem. Does it more when engine is in closed loop at normal operating temps. No codes.Anyone got an idea before i start throwing money at it.
11-25-2009, 02:01 PM
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I heard a contaminated MAF can cause this, oil from k&n filter. I would try to clean it with seafoam before you replace any parts. I would try it with mine and let you know but im waiting for my pcm to get retuned.
11-25-2009, 06:05 PM
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Get some contact cleaner to clean the maf, pull the t/b off and give it a good cleaning with some carb cleaner. You can also pull out the iac and clean the whole passage with a tooth brush. Good time to do the coolent hose bipass too.
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11-25-2009, 06:41 PM
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I would guess the throttle position sensor could cause it but I would try cleaning the maf first. I goggled it earlier and that's what worked for most, the oil from aftermarket filters a screw with it.
