JAMES.M.

Hi there!
I,m having a bit of a problem with my STI 2 and was wondering if anybody has any ideas as to what is causing it.
Under hard acceleration in mainly first & second gears i am getting a very bad hessertation or stutter, it has been like since ive had the car (about 7 weeks) but i always thought it was perhaps the spark plugs.
This evening i have changed them,before i had PFR6B NGKs and have changed them under advice from NGK to PFR7B after checking the gaps and managing the fidly job of refitting them, i have found that it hasnt made any difference!!!
In the main FAQ it says about the waste gate solonoid, does any body know where abouts in the engine bay it is and if it would make any diference cleanig it?
Please help as it is starting to get on my nerves not having proper acceleration!!
Thanks..JAMES.

Bob Rawle

Plug gaps should be 0,7 - 0,8 mm. This is important. If the gaps are as above then you probably have one or more coil packs breaking down when the spark has to jump under boost conditions. They "age" and start to produce less voltage. The higher the boost the more volts needed to make the plug spark so ... tired coil pack equals misfire under acceleration. I had exactly this problem with my Sti II. New coil packs fixed it. Approx £47.oo each plus the vat. You may find that its only one thats on the way but best to replace the set IMHO.

Bob

JAMES.M.

Bob.
Thanks for your help,do you know if there is anyway testing them to see if it any particular one?
Also do you know if the sti ones are the same as standard uk impreza?
...JAMES

Norrie

James

I've a similar problem with my MY95 WRX. However, with my car the problem has been gradual. I Haven't had the car serviced yet but will do soon so I can't compare plugs before and after. This sort of problem seems to be fairly common. BTW, did you change the plugs yourself? Is it really as awkward as it's supposed to be?

Let us know about the wastegate progress.

Norrie

Bob Rawle

James, the way I worked out which one was faulty was to examine the plugs. the mis-firing cylinder had an obviously "dirty" centre electrode insulator whilst the others were nice and clean. Suggest that you give the car a run without allowing the misfire to clean up the plugs then force the misfire to happen a short distance from home and then whip out the plugs and check. I'm afraid I don't know about the coil pack types. They are part numbered and serial numbered though so you should be able to check.

Bob

Steven Breen

The solenoid valve is located in the engine bay on the drivers side (UK) attached to the wing. It is the small brass cylinder about 1.5in in diam.

I think the FAQ recommends pulling the T shaped supply hose off and filling it with brake cleaner from an aerosol. Then go for a blast before the cleaner evaporates.

Steve

JAMES.M.

Norrie.
Yes i did change the plugs myself,i wouldnt say it was hard, just fiddley.
If my extension bar had been any bigger or smaller i would have struggled also i have a ratchet with a pivoting head which made life a little easier.
what i did was on one side take both the battery and wiper washer tank off, and on the other take the top of the air box off(getting the bottom left hand screw off was the hardest part) this made access to the coil tops a lot easier.
Hope this helps?
..JAMES
P.S.Thanks steven i have been wondering where that was for weeks, i will give it a go.

Bob Rawle

I don't think that the Sti II has the T piece. It uses a three way valve but Steve's comment holds good. Spray the cleaner directly into the top port of the three way valve. Oil in here though usually causes overboost cut out. If you have a boost guage you should be able to see the boost going too high. This causes a complete engine cut not a stutter but it may be worth a try as well.

Bob

Mark B

interesting.

just had my car serviced yesterday and they fitted new spark plugs. they mentioned to me that the ones in there were not at the right gap distance.

so today I gave the car a real thrashing and when you get to full on boost and hold it for more than 1 second the engine stutttttters so badly the boost drops to zero.

I thought *#!! that !!! tried it again and the same. So I have one of these Air Flow resetters in the dash which is always turned off. I turned it on and dialled it up to 10% and it still stuttered. dialled it to 6% and the problem went away. Have done 150 miles today. turned the AFR off on the way home and gave it some booty and the stuttering had gone.

any explainations???

Bob Rawle

Mark B

Did the car do this before it was serviced ?
Do you know what the plug gaps were and what they changed them to ?

Bob

JAMES.M.

What an 'Air Flow Resetter'?
Did it come with car or is it an after market thing?

Mark B

Bob,

I had no problems before the service, however today I gave it a hammering and I still have no stuttering even with the AFR turned off?

What do you think.

If the battery was disconnected and the ECU had reset, could it have been discovering it's new settings???????

WESTFIELD

I had a similar problem on MY99, 1st and 2nd gear cut-out under very hard acceleration, after pulling out and turning right at junctions. I was running near the empty mark with probably less than 15L of fuel remaining. I think the problem was caused by fuel starvation as it has not re-occured in similar situations with a fuller tank.

Bob Rawle

Mark B.

Yes it could indeed. The ecu resets when ever the battery is disconnected for more than a few minute and it doen't need to be thrashed to try and run more boost cos that is the default. So, it couls well have been too advanced and trying to do more on our crap fuel than it could cope with. Do you run with SUL ?

Bob

Mark B

bob,

am running on SUL. Took the car back to the garage and they have put the plug gap size back to what it was when they first looked at it. Apparently the plugs had very little gap.
Will be taking it out today for some high boost sessions to see what happens.

EVOBOY

I had the same problem with my 98 model WRX.
I took it back to the dealer and they said
it was carbon build up in the manifold. So
they sprayed some kind of cleaner in to the manifold but that did not work.The whole time
i was saying it was the standard blow off
valve.they said it wasn,t.so then i took it
to another dealer and lied to them saying i
swaped it with a friends one and it fixed the
problem.So subaru put a new one on and to
the amazement the stutter was gone further
assesment of the old one showed a crack in the blow off valve.


[This message has been edited by EVOBOY (edited 03-07-99).]

Imago

I have an RB5 WRSport which also suffers from the problem, but only noticeably in 5th between 3000 and 4000 RPM. If I accelerate hard through the gears I don't get any problems at all.
The car also surges quite badly when cold.

Bob Rawle

Mark B

Try and get them to tell you exactly what the gaps are/were. The NGK book for PFR6 (or 7) B's (or G's) quotes 0.8 mm as the gap for the Impreza. The non-platinum plugs fitted to the sport are gapped much wider and some dealers get confused between the two. If the car is modified then NGK recommend closing the gap by 0.1 for every extra 50 bhp (or part of)

Bob

JAMES.M.

Can somebody pleeeaaase tell me what a 'Air flow resetter' is.
Thankyou...JAMES.

Mark B

Hi James,

I have an AFR fitted in my car and from what I have read in the BBS, it allows you to alter the fuel/ait mixture 'on the fly' whilst driving.

Personally, I have had it on minimum and on Max and have not really noticed much difference between them. Right now I have the unit off.

But, it looks real cool sat in the dash !

vanya gant

1) I'm with westfield. My car NEVER stutters if it's got bags of gas in the tank
2) i'm with the other guy who says pleeeeeeeeeeeeeeeeeeeeeeeeeeez what's an airflow restrictor?

Mike Tuckwood

I took a friend for a drive in my WRX the other day.... He developed a stutter under hard acceleration.

Mike