V3 STI - Idle issues-MAF changed, IACV Cleaned
 

Hi guys,

Im having some issues with my V3 STI. When the engine gets warm, the idle starts to hunt only on deceleration.

Say ive had the engine running for about 10 mins from a cold start and i get the revs to around 3000 rpm and let go of the pedal, revs will drop down to 800rpm and then go up to 1200 and then keep hunting.

If i turn the engine off and restart it will idle normally until i rev it up and let go of the pedal. Only seems to do it on deceleration.

If the engine is cold and i rev it up, it wont hunt and only does it when the engine is hot.

There are no fault codes and i have swapped the MAF with a known working unit.

I have also cleaned out the IACV and components.

Thanks in advance guys.

Coolant temp sensor ?

Symptoms point to this, I may be correct.

TPS sensor

thanks guys...i'll test these out

can u smell fuel ??

IACV is still the best candidate seeing as it directly controls the idle. There is a small coiled up spring in the base that moves the pole around between when it's cold and hot which is what compensates for cold running etc. I'd definitely look at changing the IACV after checking the TPS which is fairly straightforward with a voltmeter.