Hi folks, I'm an inexperienced Volvo owner - just got a '90 745 GLE (yes, it has a new timing belt). I perused the FAQ, but can't find an answer to this problem: When cold, the car idles at 700-800 RPM, once warmed up it settles into a steady 1100 or so. I brought it to an independent Volvo specialist who adjusted the TPS and said that it's a problem with the ECU and I should live with it, since it's not terrible. Any other ideas? And about the ECU: it's a Bosch 571, which I haven't seen mentioned anywhere. Are any of the other ECU numbers compatible with it, should I run across a cheap used one?
Thanks for youanswers, and this great resource in general.

sf

SF-

I still have the same problem with my car after replacing the AMM. I was checking the FAQ's and there is a thread that stays the 89-90 700's have 3 temp sensors. one to work the gauge on the dash, and a second plug that houses 2 sensors, one of which sends info to the ECU. When this goes bad, the ECU thinks the engine is cold and dumps extra fuel, contributing to high idle, and possible like in my case, a rich mixure.

Hello There!

Did you ever resolve your high idle problem? I have a '89 760 with the same exact problem as you described. I got the car in December, and didn't have any problems, but as soon as the ambient temperature rose (like over 70 or so) the problem surfaced. I was told that it was a bad AMM, because it was mis-interpreting the ambient temperature. I swapped the part and it didn't fix the problem. And I don't know if it's related, but I failed state (NJ) inspeciton for emissions. NOX and HC were ok, but CO% was high. (1.76%, where .50% is the limit). Let me know! Thanks!

Don

If the TPS fails, then the car will idle high since the ECU does not see the "idle" signal. Check for TPS continuity at both extremes of idle and wide open. Consider that the IAC may also be weak. Finally, look for vacuum leaks in the intake system.

Assuming it's an automatic, wouldn't an idle that high stress the transmission?

i've always wondered where the stress would end up exactly. i think it would stress the torque converter.
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Kenric Tam
1990 Volvo 740 base sedan (B230F)
My Volvo 'Project'

It just heats up the oil is all. The convertor at that low rpm is fine. But I have seen some drag cars where the convertors started to "balloon" from all the pressure .

Oh it will certainly affect your gas mileage in town.