Rev lag when starting car

[Anarchi]

Hi all,

For a few months now, when I cold start the car, the revs go up to 2000rpm, lags for a second, then goes back up to 2000rpm. This doesnt seem normal to me. When the car is warm started its fine.

@0ms: Start car.
@1000ms: revs to 2000rpm
@1500ms: revs lag to 1300rpm
@2500ms: revs go back up to 2000rpm
Revs go down to 800-1000rpm once the engine has warmed up.

What would be the cause of this? Is it anything to worry about?


btw There are no ECU codes and I had an oil change 2 weeks ago - I use Castrol Magnetic natural oil.

 

[DirtyD]

so this only happens when its cold?

 

[sherpagoodness]

sounds like your fast idle valve located on the underside of the throttle body...time for a rebuild on it, to make it easier pull your whole tb.

 

[Anarchi]

It only happens when the engine is cold, but even still it only happens about every second start.

I have changed my brake pads and replaced all filters myself, is servicing the throttle body difficult, i.e. could I replace the idle valve myself?

I havent changed my fuel filter for a while, could that be the cause?