Group Captain Smudger

UK MY97 Turbo, 60,000miles: P1 (STi) backbox; K&N induction kit

Symptoms: when hoofing it it has a tendency to hesitate quite badly at times (similar to fuel starvation). If I'm brutal with the accelerator the car shudders quite violently, which the kids in the back find amusing but of course I don't. Now I can almost sense when this is about to happen. Gentle pressure on the accelerator alleviates the problem.

Thought it could be the plugs so these were recently replaced with new PFR6Bs. Old ones were mucky brown and the gaps were on the large side but the problem is still there. The only other symptom of note is that the backbox has a sooty rim. Others on this db have mentioned that MAF sensor failure can be indicated by erratic tickover. I wouldn't say mine's erratic but I've noticed on several occasions the revs dying and then picking up again (mainly on slow downhills when the engine is cold). Normal tickover (when warm) is about 750rpm.

Any help/advice appreciated.

P.S. Originally posted yesterday. This morning it was a bitch to start - kept on cutting out. Not sure if drop in outside temperature could be behind this.

mo,s scoobymonster

hi mate dont know if this would help but been quite a few threads like this and people suggest cleaning boost solonoid with brake cleaner hope that helps

Opoce

I have MY97 for a week now and have the same problem when cruising on hwy (@3000rpm) and have to overtake or similar.
Seems to be old, known and reported bug - see http://www.iwoc.co.uk/impfaq.html - Technical and Problem section - Q. After about 20 miles ...
I've just realized that yesterday so let please me know what's the cheapest way to get rid of this ...

Petr
Prague,CZ

Dark Blue Mark

Backbox should be lightly sooty, as they do run a bit rich. On boost hesitation can be cuased by a failing MAF, but as mentioned, check the boost solenoid too. I notice you have an induction kit (one of the better ones) They will lean the mixture on boost, and combine that with a potentially leaning MAF, and you have trouble.

Reset the ECU, and see what the idle does then. If it's erratic the look to the MAF. Failed MAF's are a *******, as they will cause the car to cut out instead of idling properly. They don't normally give a CEL either.

MB

Group Captain Smudger

Today's symptoms. Starts first time but then tickover drops. First part of my usual journey is downhill (approx. 400yds) and by the time I'd reached the bottom it had stalled. CEL is on continuously from initial start until after 10mins or so. Recent mpg is nearly 10% better but that's probably because I'm easy with the accelerator pedal at the mo. I did "The Judge" 3000rpm test, and the rev drop was as he described it should be - fast to 1200-1400 and then steady to 750-800rpm. Also the motor has passed the "unplug the MAF and see if it stalls" test.

So if it's the lambda sensor and not the MAF:

1. should I fit a Subaru part? (MY97 3 wire I believe)
2. if not which make and from where should I get one?
3. are they easy to remove and fit (compare with changing spark plugs)?
4. BTW the MOT was passed nine weeks ago
5. BTW now running with standard airfilter

Dark Blue Mark

Whats the ECU failt code and did you reset the ECU as suggested?

Again, read my bit about the induction kit.

I still dont think its the O2 as this takes a few minutes to come into life from a cold start. Fuelling / idle is governed by the ECU.

I still think its the MAF
If you want an 02 sensor, you can get them from cats direct, or get an OE one for a bit more money. Its easy to remove, and lives in the downpipe. IMHO, its good practice to change is every couple of years.

MB