I have a '95 Mondeo 1.8 which is very slow to return to normal idle speed when coming to a halt. It starts and runs ok, but when coming to a halt the idle speed stays at between 1500 & 2000rpm for two to five seconds before dropping back to 950rpm.
Gunsons Fault finder gives fault code of 327 (EGR system exhaust gas pressure differential sensor) though I've seen a suggestion that this is normal / often happens! Anybody suffer the same problem or know what the cause is?
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My daughters Fiesta does exactly the same. It was previously my wife's car and it has done it regularly for the last few years. It has been dealer maintained from new. Not very helpful but I wouldn't worry too much. I had a '98 Escort that did it very occasionally as well.
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our mondeo idles high some times, espcially in hot weather - normally disappears after a while. Had similar prob with the Audi 2:3 a few years back.
some one told me it was the "electroic brain2 that needed replacing at vast cost - i did not and the car was normally ok,
the brather valve may needs cleaning.
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This problem can be caused by the signal from the throttle position sensor. After a period the voltage from this sensor at the idle position will exceed its operating parameter. The ecu then does not recognise that the throttle is shut and waits until it sees a zero road speed from the vehicle speed sensor before allowing the idle speed to drop from the 1800 rpm you state. Try removing the 3A (purple) KAM fuse from the fusebox for 10 minutes or so then replace it and start the engine without touching the throttle, go and have a cuppa then take the car for a run in various traffic conditions. Removing the fuse makes the ecu lose its adaptive memory which triggered the fault. When you restart the engine the ecu sees the voltage from the throttle sensor and whatever it is (within reason!) logs it as correct for a closed throttle. Normal operation is when the engine speed should hang up (not increase) between gear changes and wait at 1100 rpm until the vehicle is stationary then drop to 900.
Andrew
Simplicate and add lightness!!
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