After a fairly spirited drive back from St Albans to Oxfordshire I think the beastie may be in trouble.......no real thrashing for her but some v high speeds 130mph (private dual carraigeway http://bbs.scoobynet.co.uk/wink.gif ) but about 3 miles from home these symptons started :
On boost in top and she suddenly stops accelerating for a split second and then carries on....then in third gear coming out of a roundabout the same happens......
It feels like fuel starvation/surge but she has nearly a full tank in her so it cant be......
I'm quite concerned so any help and opinions would be appreciated...
MY 97 Wagon
Standard
97 BP SUL all the time

Cheers amigos

Richard,

IANAM (I am not a mechanic), but it does sound like you are just experiencing the "fuel cut" thingy. You may have opened her up a bit with spirited driving, and now boost gets a bit too high for the standard ECU.

Is it "face to windscreen" type of hesitation, or just splut-splut ?

On a related note: I still don't understand why an Impreza gets "lazy" after some normal driving, and needs a bit of trashing before it gets to max boost/performance ? Anyone know ?

Theo

Rich,

It does sound like your suffering overboost and may be worth checking that there's no oil contamination in the hoses that run from the turbo to wastegate actuatior and wastegate actuator solenoid where the restrictors live... the ecu will momentarily cut bfueling if the boost is over 1.2 bar I think...curtainly did when I played with the restrictors on mine http://bbs.scoobynet.co.uk/rolleyes.gif

Theo,

The standard Scoob ECU aledgedly adapts to your driving style, so if you do pootle round for a bit it tends to go into an 'economy' mode http://bbs.scoobynet.co.uk/wink.gif give it a good thrash and it remembers what it was meant to be doing in the first place...suposidly...

Wastegate solenoid needs cleaning. Brake cleaner will sort it.

Check your oil level too Rich.

R

Sounds like the "overboost" problem I had about a year ago in my MY97 wagon. Cured by dealer putting in a smaller diameter restrictor to the sensor dooberry I think, although I'm sure its down a few horses since this was done... http://bbs.scoobynet.co.uk/frown.gif

See Stev Breens FAQ for more info (in here somewhere:

RICHARD ,tim is right it sounds like you run has pulled oil up to the boost solenoid,have a look on the SIDC web site ,you'll find all you need to know to clean it,This is common on 97 cars. tommy.

Richard,

Have a look at

Tim, yeah, I understand that bit ... but it gets spookier when I tell you I have a Unichip setup.

Normally the car is a bit more sluggish because the boost drops a bit after a while. OK, understand that. Standard ECU may adjust the pulses going to the boost solenoid.
But in my case it is the Unichip (with boost controller) that drives the solenoid, and not longer the standard ECU. And guess what ... same thing happens.

After some lazy driving, boost is about 0.1 bar lower than "normal". Give it some stick, and it's back to its original level.

Question than still is: why ? Unichip setup re. boost is pretty straightforward (% of duty-cycle at different rev points) and is in no way related to other parameters. Fuelling is not changed. Standard ECU will surely not retard ignition because you are poodling around (that would be daft).

So ... why ? http://bbs.scoobynet.co.uk/biggrin.gif

It could also be the fuel filter. Over time they fill get water in them and need replacing. The water molecules are too big to go through the filter and thus in turn stop fuel going through, creating the symptom you described. Dont know if this is as much of a problem in modern day cars as in older ones though.

If it is this it'll be cheap as chips to fix.

Theo

Bit off the orignial topic I know, but it is Richard http://bbs.scoobynet.co.uk/biggrin.gif

I'm not sure how the unichip works Iknow it's a piggy back board onto the standard ecu, does it control ignition and fueling? If so I have a clue why your experiencing the problem, unless of course it's something too do with a build up in the engine of crud with the mad Unichip setting http://bbs.scoobynet.co.uk/biggrin.gif while your trying to behave!

Gerg,

I had a problem with the fuel filter in mine after a dodgy batch of fuel which caused a lot of det, but the car went like hell! And oh how I wish they were cheap, std IM dealer price is around 60 quid! Although I have bought the correct one from another source (powerstation) for 12...so not that bad really http://bbs.scoobynet.co.uk/rolleyes.gif



[This message has been edited by Tim W (edited 27 April 2001).]