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Reliant High Idle

Q. Dear Bob: I have a high idle problem with a 1987 Reliant 2.2 auto, 220,000 miles - that's not a typo, throttle body injection, A/C. Over the years, the idle speed has crept up. The idle speed control system seems to work, initial high idle drops immediately after starting as it should, but it does not come down as low as it should.

Throttle sensor is good, a nice clean sweep on my analog VOM is displayed but I changed it anyway. Distance sensor is also good, coasting to a stop in neutral causes the idle to step down when the car is almost stopped. Again good. Just for a check, I borrowed the entire throttle body assembly from a friend's car with good idle.

On my car, idle was high with the different TB. The borrowed TB was from a 2.5 liter car, if that accounts for the difference. No trouble codes are present. I believe excess blow by through the PCV system is providing excess air into the base of the TB. Disconnecting the PCV system causes idle speed to soar, and plenty of "smoke" from the breather. Is this fixable, or should I let it be? This car has been unbelievably reliable.

My "it has to be Japanese to be good" friends consider this a freak. The only weak part of this car is the MAP sensor. You should see the collection of failed units I've amassed since I bought it used. A spare is a must!

Thank you,
Dave

A. Bob's not here Dave, but if you don't mind, I'll try to help you out. Bob's in school for the next two weeks. He's learning how to operate a garden hose.

FYI, the 2.2 engine in that car is a Volkswagen engine. If you look on the block you will see VW stamped on it.

The most likely reason you have a high idle in that car is because there is too much unmetered air entering the engine. If you can't get the idle to come down by turning the idle speed screw in, then you'll have to find where the unmetered air is coming from. Most likely a broken vacuum line or cracked PCV hose.

The blow by is coming from weak rings, only a major engine overhaul would repair this. My opinion is this car is not worth it.

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