Over the past few days i have started to notice that at 4250rpm the car stopped pulling as hard, i.e. the rate of acceleration suddenly drops, then as the revs hit about 5000rpm it stutters until hitting about 5500rpm, then everything picks up and goes as normal. This all started of hardly noticeable but was steadily getting worse so i booked it in for next tuesday. On the way home last night i got caught out for fuel and ended up having to put standard unleaded in. Within 20 miles the symptoms have totally gone away!

Any thoughts??

I'm going to put the usual tank full of optimax in today and see what happens.

(Car is an MY02 WRX)

 

It sounds like a coincidence.
Stuttering under heavy load (ie hard acceleration) usually indicates an electrical problem - have you checked HT leads, distributer etc...?

Gastro

 

Perhaps with higher octane fuel in the car is detting and the problems you feel are it backing off. This could be "fixed" (i.e. dodged round) by switching to the lower octane fuel. Assuming you have a UK car, the lower octane fuel will cause the car to switch to the lower octane maps which are far more conservative which probaly don't cause the problem. Of course, you get less performance with the lower octane maps.

Perhaps you have a problem say with a MAF sensor which is on it's way out, causing the car to run lean, and when on the higher performance maps, this causes det.

Just a theory but I would get it checked out!

Matt

 

I have just replace the standard air filter with a new performance panel filter, so i was thinking MAF sensor.

The thing is i had the same thing happen about months ago, took it to the garage and when i picked it up it wasn't happening but they said they didn't find anything wrong and did nothing.

 

i would check the coil packs. had similar probs with old scoob, tuners said nothing wrong, changed plugs, fitted FCD but it was the coil packs all along.

just a thought....

 

just occured to me that it seems have tied in with the weather getting really $hitty and wet