I'm determined to get this problem nailed this summer. It's not something which really affects the driving of the car as such but it's starting to annoy me now.
When the engine speed is dropping from say >2500rpm back to idle (like for example when approaching a junction and dropping the clutch) the car almost stalls but then the ECU catches it and recovers to normal idle speed. Only takes about half a second or so and never actually stalls but I know this is not normal behaviour.
It can also be demonstrated just by sitting the car in neutral, revving to 3000rpm or so and coming off the gas quickly. You get an undershoot of rpm but then it catches and idles normaly.
So far I have replacd the idle control valve and the throttle potentiometer (the one on the engine rather than the one on the accelerator pedal). All to no avail.
I mentioned it to the main dealer once when I was passing, but the chief tech there (Victoria BMW, Harrogate) said it didn't even have an idle control valve. All confidence in them even opening the bonnet evaporated in a puff of smoke at that point.
Does anybody have any suggestions of what to try next? I was trying to find some tech data on the throttle pot on the accelerator but couldn't get anything from either cardata, RealOEM or the TIS disc???
When the engine speed is dropping from say >2500rpm back to idle (like for example when approaching a junction and dropping the clutch) the car almost stalls but then the ECU catches it and recovers to normal idle speed. Only takes about half a second or so and never actually stalls but I know this is not normal behaviour.
It can also be demonstrated just by sitting the car in neutral, revving to 3000rpm or so and coming off the gas quickly. You get an undershoot of rpm but then it catches and idles normaly.
So far I have replacd the idle control valve and the throttle potentiometer (the one on the engine rather than the one on the accelerator pedal). All to no avail.
I mentioned it to the main dealer once when I was passing, but the chief tech there (Victoria BMW, Harrogate) said it didn't even have an idle control valve. All confidence in them even opening the bonnet evaporated in a puff of smoke at that point.
Does anybody have any suggestions of what to try next? I was trying to find some tech data on the throttle pot on the accelerator but couldn't get anything from either cardata, RealOEM or the TIS disc???
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