Idle control

[Stephen]

Ali
The symptoms you note are almost identical to those I had with the stop keeping the butterfly slightly open.

[alicrozier]

The tell was the throttle didn't hit the stop when engine running. Did with it off...

[robin]

Robin I reset the TPS etc as you suggest. I think there may have been too much air getting in when the TPS was telling the ECU that the butterfly was closed. A mechanical rather than electrical issue.

What do you think happened to mean that the engine needed less air at idle than when first built? I agree that what you did might well have cured your problem. What I am querying is whether it was the "right" fix.

Cheers,
Robin

[Stephen]

Hi I didn't give you the full background. When I got the car it had a 56mm throttle body which affected the cable length and generally caused the car to run like a pig. I replaced it with a second hand 52mm as should be fitted to the car. It was this second hand 52mm which seemed to have been adjusted at some point before I fitted it. The stop was set such that it prevented the throttle butterfly from fully closing.
S

[robin]

OK, so that makes sense for your car, but assuming nobody has adjusted the factory-fitted and factory-set throttle stop on Pete's car, it is really unlikely that it should be the cause of his problem. I am just writing this here so that in future when somebody searches for this issue they are not tempted to adjust their throttle stop in order to address idling issues. Of course if, like you, they are starting with a throttle that somebody else has messed about with, then clearly it is not unreasonable to try to return it to a better setting.

Cheers,
Robin

[Stephen]

Agreed