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Old 03-24-2021, 04:35 AM   #9
LH-Jet & Carb Free Zone
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Join Date: May 2003
Location: Duvall, WA

On LH 2.0 and 2.2 cars, the engine should flare up to ~2000 when the engine first starts, then drop immediately to 750 rpm. Another thing to check is the TPS. Make sure that it clicks each time you move the throttle plate by hand. That said, your problem sounds more like advanced timing or a vacuum leak somewhere. If the TPS intermittently clicks, the idle will pretty much be all over the place, ranging from anywhere between 750 and 2400 rpm.

Yet another thing to look at... AC switch. Needs to be all the way over to "0" to turn off the idle boost function. If it is, there's still the possibility that the flap on the side of the switch isn't depressing the microswitch completely. I've had that occur in the past. With the car running, and the center dash console pulled out enough to reach the wires behind it, pull one of the wires on the left side of the AC switch. If the idle drops to something more reasonable, you've found your problem.

1982 242Ti - black, M46. 1985 245Ti - blue, M46 - soon to be for sale.

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