Birdie00one

Hi there,
I've recently purchased an Impreza Turbo 2000 (w plate) and its hesitant, especially at low revs and when its cold. It just refuses to rev cleanly and revs only in pluses i.e it goes, then it doesn't, then it goes, then it doesn't and so on....

So far its had a new airflow meter, oxygen sensor and plugs. Now its been suggested that the blow off valves at fault. Has anyone else had this problem and has anyone heard of this cure????

Cheers.

Scott.T

iTrader: (2)

MY99/00 are quite prone to this when cold. It's due to the oxygen sensor not yet being up to temperature and providing a false reading to the ECU.

Try disconnecting the oxygen sensor then go for a drive under the same cold conditions. You should find it alot smoother.

This is due to the ECU using the fuel base map rather then adjusting the fuelling according to the oxygen sensor reading.

You probably won't even see the 'Check engine' light come on with the oxygen sensor disconnected. So you can drive like this all the time, although when warmed up the fuel economy will be slighlty worse at low/cruise speeds.

Shell Optimax can also cause more hesitation when cold, so try swapping to something like Esso SUL. It won't stop the hesitation, but on mine it did improve it.

Birdie00one

Thanks for the advice I'll give it a try.