Biggles0509

Car: MY2000 Impreza Turbo with 105,000 miles on the clock. All gentle and mostly long motorway runs. No smoke or rattles. Mechanically standard. Regularly serviced by Subaru.

Has developed the following problem:
Originally a "misfire" under hard acceleration which wasn't cured at Subaru service has now developed as follows:
Accelerator pushed flat to floor at any speed in any gear produces no acceleration. Accelerating gently does produce increased speed (just). When engine is warm the car will do no more than about 40mph - trying to accelerate produces what almost feels like a misfire accompanied by a hissing noise from the engine.

Has today come back from the garage still not fixed - cam belt checked today and garage has admitted they do not know what the problem is. They will now swap bits with another Impreza until the fault no longer exists

Is this a known problem as I can see me paying a fortune in labour fees to pay for bits being changed that don't need it?

scoobyboy

air flow sensor , boost solenoid valve , o2 sensor my money is on the air flow sensor

vulnax999

iTrader: (7)

Split boost hose?

Biggles0509

Thanks.

nom

To add to the split boost hose, split intercooler hoses - those under underneath the top-mount are prone to splitting (heat cycling from the engine/gearbox). Unfortunately, it's quite hard to see if they've split or not... from the sounds of things, at WOT the turbo is producing boost (woosh) but it's not getting where it's meant to be (engine ), so it's disappearing somewhere along the inlet path from the compressor outlet up to the inlet manifold. That means... crack in turbo (unlikely 'cos it's the cold side), pipe from compressor > top-mount (or potentially the actual connection between the hose & housing/top-mount), the top-mount itself (possible - it does happen, but it shouldn't on the model that you have), and possibly the itty-bitty tube that goes from the top-mount to the manifold. Many tuning companies insist that this tube is uprated before they raise the boost - i.e. they are known to cause problems at only marginally over the standard boost level!

wacky.banana

Biggles,

YHM

vulnax999

iTrader: (7)

Yeah Nom, that's what I meant, you just said it better!

Biggles0509

Car sorted today by Subaru dealer - with a little guidance from SIDC!!
It was the air flow sensor ( not working at all) plus dirty connections on the idle speed control valve (giving falls readings to the ECU).

Grin factor has returned!!!

Thanks for your help and interest guys.