Impreza Turbo - engine holds revs when stopping

[Escort2dr]

I'm currently looking to buy a 'classic' Impreza Turbo UK spec, which comes with a s/s exhaust, air filter and dump valve as the only mods. The car is quite tidy but I noticed on the test drive that when taking it out of gear when stopping at a junction, the engine revs stayed high and then dropped to idle after a few seconds, rather than dropping back down straight away.

I am quite interested in buying the car but wondered how much this issue would cost to fix? What might be the cause?

Cheers.

[GavinPearson]

Likely cause is the throttle damper if it has a cable. Very easy to fix if that is the case.

[dnb]

Sticky idle control valve or the airflow meter wearing out are other causes. What year car? (This determines how likely an airflow meter problem is)

[Escort2dr]

It's a 1999 V plater. What's the likely cost of the things you mention please? I'm guessing around £80 for the MAF.

[anonymous-user]

V unlikely to be a MAF fault with those symptoms, i'm with GP (^^^^^) on this one ;-)

[stevieturbo]

Max_Torque said:

V unlikely to be a MAF fault with those symptoms, i'm with GP (^^^^^) on this one ;-)

There is no throttle damper on a Subaru. Could be an idle valve problem, air leak, dump valve...many things

But it should drop to idle like any normal car.

[GarryA]

If its an oiled filter it may have ruined the MAF, common on Imprezas.

[stevieturbo]

GarryA said:

If its an oiled filter it may have ruined the MAF, common on Imprezas.

Myth.

Plenty of MAF failures with standard air filters too. In fact...wouldnt really matter what filter on 99/00 cars, they just fail.

[dnb]

Max_Torque said:

V unlikely to be a MAF fault with those symptoms...

My 99 plate STI has "eaten" at least 3 MAFs in the last 7 years I have service records for. Yes, they do just fail. One of the early symptoms one one occasion was a slow return to idle as described. Obviously an air leak or IAV fault can easily cause the same symptoms.

[SteveTusc]

I had a MAF fail on both of mine. Both times they did what you are describing.