The car would drive normally while accelerating. But, during deceleration all the way to a complete stop, the idel would hover around 1200 to 1500 RPMs and pulsate for about 20 secs. After that, it would gradually come down to 900 RPM's. Once it gets there, it would be stable and normal. Does anybody know what can be wrong. On colder days (30F and below), it does this on higher RPM's (around 2K) and pulsates longer.

Of course, this would be more noticeable when sitting at a light after normal driving. I thought it would go away after the car warms up. But, it does not.

Thoughts anyone. Much appreciated.

First thing to check is the idle control valve -- may be sticking open.

Usually, that causes stalling when coming to a stop, however, as it sticks closed more often than open. Worth a try, anyway.

Otherwise, your overvoltage protection relay may be bad, causing the idle control circuit to fail (high idle).

I would also verify that the throttle position switch is working so that the computer knows it's supposed to be idling the engine!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Great. I'll check all that. Where's the idle control valve? Can you give me a description of what it looks like. Thanks.