Bigpower

scoob has been hesitating and holding back some times, had a new fuel filter fitted and fuel pump so i'm guessing fuelling is ok.
could it be the coil pack or an HT lead?

it trys to idle at 250rpm and splutters when you press the throttle.

when i turn the ignition off and re-start it the problem goes away :?

i guess at worst case it's the ECU, booked in thursday for a rolling road so hopefully that'll shed some light on the situation

could be faulty o2 sensor removing to much fuel on idle but hard to say with out reading live ecu data

or an intercooler pipe loose ?

does it try and hunt on idle as well??? if so it could be the MAF sensor, these are pretty weak on the later classic Impreza's, and a common fault. For safety don't go trying to drive the car hard on boost till you find the issue as the fuelling will be way out and probably very lean.

Is it running a standard ECu, if so you can do a check of the fault codes by connecting up the diagnostics connectors under the dash, if you do a search on the net it'll tell you how to do this and also how to read the codes.

sounds like it could be the maff, try unplugging the maf and see if its the same
im not sure what version yours is but if its a version 3/4 and if you can get to colchester your more than welcome to try mine

If it is v3/4 and turns out to be the MAF, I have a secondhand one you can have for

we do V5/6 ones for

thanks for all the options guys, the car started to play up at 70mph and was only when i pulled into a layby that the idle was low, and sounded like it was running on 3 cylinders.
The idle control valve gasket was recently replaced, would this affect anything while driving at speed if the valve was faulty? I understand it could be the MAF or O2 on idle but what about when driving?
cheers.

dave

Could be the MAF whilst driving if it was misreading airflow figures.

It could be the O2 sensor too as it would still be in closed loop but it depends on what you mean by 'playing up'. A small amount of richness wouldnt cause too much of an issue but running a little lean would make it jerky as would running a lot rich.

Is it still playing up when in open loop - ie when over 4300 rpm ?

Could still be intercooler hose/s loose or split.

I'd take it to somewhere that can hook up to read the ecu data to see what is going on.

Easy way to rule out the O2/Lambda sensor is to just unplug it and see if that makes a difference.

But if it sounds like its running on 3 etc that sounds like something else.