mk4 astra 1.4 16v idle problem

[drnick]

Recently bought one of these for the missus and it failed the mot on emissions so ive replaced the o2 sensor as was advised it could of been that and now it only idles correctly for a few seconds after starting then rises to about 1500-1750rpm and stays there, could it be a faulty sensor or something else?

[DaveGib]

If you take the sir intake pipe off the throttle body and check if its oily and greasy inside. If so it needs removed cleaned and then refitting.

Its an easy enough job to do

[drnick]

what is the sir intake pipe? Ive cleaned out the throttle body with some carb cleaner but that hasnt made any difference!

[DaveGib]

sorry rushed the reply it was supposed to say air. It is the throttle body did you clean the small breather hole that comes into the throttle body near the butterfly. I used to use 1 strand from a wire brush to push through and spray with carb cleaner as you have said you have done. I also used to disconnect the battery for 15 mins to reset the ecu. When you start the car up dont touch the throttle pedal just allow the car to settle at its own idle point. This used to sort the problem when I worked on them.

Hope that helps