1988 cadillac deville-Help

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- brian ellis
  
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posted
20 years ago

Wed, Sep 10, 2003 1:18 AM

the vacuum lines have been replaced, spark plug and wires changed, compression tested each cyinder. the engine is in great shape. this car still has an high idle speed. i replaced the idle speed control motor, which had a broken plunger. The replacement unit has an adjustable plunger, but i dont know what the setting was on the original plunger.

What is the proper length for the plunger so that the car will have the proper idle speed?

thanks in advance

ps...i hate these computer controlled engines.

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- Rich B
  
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posted
20 years ago

Wed, Sep 10, 2003 3:44 AM

Thi should be a simple matter of pushing the pintle (plunger) in with your thumb while holding the IAC. Some need to be rotated slightly while dong this. Anyway, these self-adjust when the vehicle speed exceeds 40 mph (at least on all the ones I've seen). Check any good service manual for instructions specific to your vehicle. If you still have a high idle you may want to check for a leak at the TBI mounting gasket.

****************************************** I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. ~ Thomas Jefferson ~

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- Rich B
  
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posted
20 years ago

Wed, Sep 10, 2003 3:47 AM

I forgot to mention that you should depress the plunger before installing it to keep from damaging anything and so that it can adjust itself to the proper length.

****************************************** I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it. ~ Thomas Jefferson ~

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- Robert Hancock
  
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posted
20 years ago

Wed, Sep 10, 2003 4:05 AM

The ECM is supposed to adjust the idle speed automatically. Some cars need some persuasion to make them reset the idle speed - try disconnecting the battery for a few minutes, then after you reconnect it, turn the key to on for 30 seconds or so before you start the engine to give it time to reset the valve position.

If the idle speed is still too high, it's likely either a vacuum leak, or some kind of wiring problem between the IAC and the ECM, or the ECM is bad..