Im new to scooby ownership and have myself a 98 STi V4. Ive had it a about 2 weeks and its been absolutely fine, I have also recently fitted myself a Blitz DTTDC Turbo timer (All seems to be ok with this though as it was just plug and play).

However driving into work this morning i went to give it a little bit and when the car got over about 4.5k it cut power and started violently shaking back and forth? Not cut power as in switched off, but cut engine power?

I tried it again in a different gear and it accelerates fine again up to about the middle of the rev range and then again a sudden cut of power and the car shakes back and forth?? Its then really slow to respond again on the throttle, building up the revs, comes on boost and then bang, the same happens again?

It cant be anything too serious as it was fine until yesterday. But I have no idea how these boxer engines work so ive no idea where to start! ANY help would be much appreciated.

 

Has your speedo stopped working?

 

No the speedo still works fine, everything works as it should. No CEL or anything, just this hesitation above 4k. Its like it is in limp mode or something.

Tried a few searches on here too, could anyone post up the link to performing your own self doagnostics please? I cant find it.

Could be MAF sensor? Boost Control Solenoid? Dump Valve sticking?

 

Does it do it all the time, or only at full throttle? mine is doing this at the moment, but only when throttle is fully depressed. if i use about half throttle, it runs all the way up through the rev range.

I have had it Dyno'd, and turns out the neutral position switch is faulty, and causing it to stutter, almost like hitting the rev limiter, but at around 5500rpm. DON't take it to a subaru dealer, as they won't be able to find the fault (as i found out!!!)

I cannot take credit for this, as originally TonyBurns suggested it might be this on my car, and Scoobyworks in Loughborough confirmed it by rolling road. car is going in today to have new switch fitted (its not expensive, Approx. £60 + £40 labour). Scoobyworks said they have had quite a few with this problem.

For additional info, here are the threads I have posted on about this problem before, hopefully they might help:

https://www.scoobynet.com/general-te...ew-member.html

https://www.scoobynet.com/general-te...loody-car.html

 

Thanks Loco. I have a veriety of things noted down now what it could be but I suppose without sheer guesswork (which i cannot afford) or taking it to a diagnostics centre im never going to know.

Ill clean up the MAF and Boost Solenoid when i get home, check the coil packs for splits under the boots, WD40 my dump valve and then im fresh out of free ideas.

I just need this link to performing the self doagnostics to see if it throws a code....

Anyone?

 

Overboost fuel cut? Do you run a boost gauge?

 

well as i mentioned in my initial post i have the Blitz DTTDC and that has a function on it that measures my peak boost. Its standard VF23 and has never hit more than 1.3 bar before full throttle in 3rd.

Im taking it the way you are goin here is wondering if its had a boost spike and subsequently auto cut?

I dont think it has, but ill check it at dinner.

 

Whats this fuel cut business all about?

If my car is overboosting and hitting the fuel cut, how do I remedy it?

As ive said before the Blitz device has read boost up at 1.3 bar max before, but It wont reach anywhere near that now. Its less than 1 bar and then this happens...

 

check your spark plugs and gap, do you know what make they are ? also what's been done to the car to allow boost up to 1.3bar cos that's over standard

 

No idea whats been done to the car to be honest, I only found out what it was boosting too because i fitted this tubo timer a week ago and it has a peak boost reading on it.

Turned out something had just got wet on the car it seems? as it was raining heavily the morning it happened and had stopped and dried by dinner, took it back out and it was fine?

Like nothing had happened.

Seems theres something intermittent on the car as ive had a few little blips since, over the weekend. But nothing like the bogging down it was doing that morning?

Any ideas?

Wet filter and a wet MAF was my guess?