As promised here is the update to my engine problem.

Car went into the dealer yesterday. They replaced one coil pack, and fitted a set of plugs. Re-piped the amal valve and fitted a new knock sensor.

Car was road tested by two different people to confirm that problem was fixed.

Knock sensor was replaced as a precaution but was not thought to be faulty.

Plugs were gapped correctly and replaced as a precaution.

Amal valve had been disconnected so that boost could be limited to 0.5 bar when problem first showed itself.

Other three coil packs had been replaced just before I had the car. (the fourth was not changed by mistake)

New coil pack cured the problem.

A quick blast last night to check showed the following.

Boost peaking at 1.2 bar falling back to 1.0 bar and holding. (does this seem about right anyone?)

From 3000 rpm and 0.5 bar vacuum in 4th applying 50% throttle peak boost reached at 3800 to 3900 rpm.

Driving to work this a.m. in my normal "autopilot" mode (as you do sometimes) I woke up to find that I had lost traction on roundabout exit due to the car taking off in second and third far more aggressively.

Guess I'll have to stay awake in future.

I've seen a couple of posts relating to the difficulty of fitting boost gauges, i.e. where do you put it. I have used a single instrument pod (a VDO one from Superchips) and mounted it inverted off the lower drivers corner of the windscreen glass. All pipes and cables can be routed out of the gap by the pillar. I made up a small cowl to fit over the end to stop glare. This position puts the guage always in the drivers eyeline and I find that really helps when driving quickly. It looks tidy and does not obstruct vision. No holes in dash and very easily transferred. Bonded to the glass using double sided tape (black, not light coloured).

Any thoughts on what is normal for the boost on this model of car greatly appreciated.


So despite the trauma of buying a vehicle and immediately having it go wrong on me I'm now very impressed. Having tried a 280 ps car I'm very keen to get this rolling roaded as it feels just as quick on the road despite being a 5 door and hence heavier.

Bob

MY96 5 door Sti
FGK exhaust
K&N panel filter
No misfire !!!

Thanks for the update, Bob - I have been waiting with baited breath. As I work away from home all week, I have not had an opportunity to check the condition of the coil packs, so I will look on Sat before commiting to any more garage time. However, Fred (on the other thread) says he has replaced all packs to no avail. I am convinced it is a misfire, so will look at plug gaps (again). Shame, 'cos the skin on my knuckles has only just grown back.

As an aside, has anyone any tips on removing the plugs without injury? And a similar question to Bob's - what boost should I be getting on my '93 WRX?

Thanks and keep up the good work,
Zip
PS: Bob, could you post a pointer to this new thread at the end of the last one? Thanks.

1.2bar - 1.0 bar : sounds ok..spiking before stabilising seems norm if you dont have a boost controller.

Having enjoyed myself immensly on the drive to and from work today I couldn't resist investigating the amal valve piping to see that it had been re-connected properly.
I discivered that there was a restrictor inserted into the vent pipe of the amal valve with an approx. 1.5 mm orifice. Now I was not sure that the correct pipes had been fitted to the correct locations but picking up something that I read on Colins web site I decided that this was definately worth removing as it would be slowing up the rate that pressure was bled away and thus slowing down the boost response.

The result was ... 1.4 bar peak boost settling to 1.2 bar steady. The boost rises much more quickly as well with a significant increase in the "surge" that we get when the turbo is kicking in. At these levels of boost it must be getting close to its shutdown point as its a standard ecu so I'll leave well alone and see how it goes. It definately confirms the coil pack though. I couldn't get it to even think about these boost levels before it was replaced. Plug gaps are set at 0.8mm.

Just a point, whilst I'm quite comfortable doing all these tweaks I've had alot of experience tweaking my previous Cavalier Turbo. If anyone decides to try this sort of thing then BE CAREFUL. I'm using a boost guage to check what is happening and my foot was always ready to lift off the throttle at the first sign of any engine misfire, pinking or whatever.

Bob
MY 96 5 door Sti
FGK exhaust
K&N panel filter
1.4 bar boost and no misfire !!

bob or someone else,

Can you tell me what's exactly the "amal valve"?
It's the first time I read this (and english is not my maternal language)...

The amal valve is the boost control solenoid. On my car it is attached to a plate on the suspension strut mounting on the left side of the car looking into the engine from the front.

Bob

YES PLEASE

never heard about an "amal" valve
what on earth is it!?

THANK YOU

SORRY

It seems my question came a minute too late

but THANKS for the explanation .

good day

I really don't know anything about anything but, have you seen Steve's FAQ which mentions a problem like these at
http://homepages.enterprise.net/srb/impfaq.html
The relevant passage begins with the words

"After about 20 miles, when it's warmed up, the engine momentarily loses all power (quite violently) if you give it a more than half throttle, between about 3000 and 5500rpm."
You probably know all about this, but just in case.
I do not even own a Subaru.

Timothy thanks for the info. Yes I have seen this. My problem is completely solved and was not related to contamination. What I am doing now is using a golden opportunity to try and identify what, if anything, influences the boost profile and levels of this particular car in the hope that it may provide info and help to other owners of similar age vehicles. Its not a standard Sti but has a FGK exhaust and a K&N panel. Those that have driven it maintain its performance is every but as good as a 280ps car. It is a 5 door 260ps car by vin number.

Bob

Hello all once more - managed to bust the company laptop a couple of weeks ago, and am only just back online.

PTS checked the condition of all the coil packs, and discovered the one on the front offside cylinder (nearest radiator) has had a shoddy repair with what appears to be a silicon compound at some point. So - 4 new coil packs, and engine running much much better, but now cutting out at 7.5psi for some reason. Found a restrictor in the hose running from the top of the manifld to the amal valve, and removed it. Engine now boosting to 15psi before cutting out, so bored out the restrictor just a little, and replaced it in the pipe. Now boosting regularly 13psi, peaking at 14psi, and all seems ok (and very fast, thanks!) PTS (Paul Solbe) had a standard '93 WRX (like mine) in last week for ECU remap, and it boosted cleanly to 10psi in standard form, and now runs 15psi with related fuelling adjustments, so I think I'm not doing too badly with 14psi on a standard chip - probably nearing its limit on standard fuelling, but I STILL don't have the answer to what the standard boost should be on a '93 WRX?? Does ANYONE know? Will it blow up!?

Anyway, as promised (Fred / Bob) I said I'd keep you updated. The short of it was that the coil pack was buggered.

Cheers all. Any comments?
Zip

PS: PTS do a full remapped ECU for £280 (NOT the one advertised on their webpage, which is the same as a Superchip, but a new one sourced from Australia)