Bob Rawle

The crank position sensors were changed, no effect, in fact most sensors except the knock sensor (on order) and coil packs have been changed. In order to monitor the coil pack output its difficult to connect. Current monitoring the supply cables might pick something up I suppose but not for certain. Fortunately all this is being investigated under warranty. I was discussing the problem yesterday at a track day and the coil pack issue has been seen on at least two cars by one tuning company I spoke to and its not an enormous cost to find out. Thanks for your input. The more people who contribute to these problems the more likely we are to find solutions. Knowledge is power ... as they say.

Bob

Bob Rawle

At the risk of boring all those who have later cars I thought that there
might be some interest in the latest news on my engine problem.
Having spent yesterday at Castle Combe in the company of Chris Stuart who
owns Regal Autosport in Southampton the topic of my car inevitably came up
once I'd finished admiring his supercharged Vectra. (oops) It was he that
suggested the coil pack possibility.
So this morning I decided to have a look at the plugs and the coil packs for
any tell tale signs of this problem.
Once I'd shredded the backs of my hands getting the plugs out ... much
easier once I worked out that it's smart to remove the battery and air box
first... I discovered that one plug was showing obvious signs of misfiring.
This is the offside cylinder nearest the bulkhead. Also plug gaps were in
the order of 1.2 mm. My experience of turbo's said that this was excessive
so I cleaned them up and re-set them to 0.8 mm. The coil packs looked ok
except that the one on this cylinder had very discoloured "potting" compound
in it and its serial number was much lower than the other three.
Put it all back together and set out for a test drive. Because of the
severity of the problem the boost control system has been bypassed and the
actuator directly connected to the manifold with a bleed valve to limit
boost to 0.5 bar. I gradually adjusted this to increase the boost and can
now run 1 bar with no signs of the engine misbehaving !!
This would very much explain why the problem had not been found using the
high tech diagnostic gear that dealers use. This type of thing is very much
"seat of the pants" stuff.
Any way a call tomorrow to suggest that they fit four new coil packs and
four new plugs correctly gapped with the boost control back on line and I think I'm in business again.

Any one has any comments then please make them. If this is a first
occurrence then perhaps it should be added to the FAQ on the SIDC BBS.

Incidentally, I'd recommend the K&N panel above any other without
hesitation. It fits well and it filters well. I've used them for 5 years now
and can safely say that I've found them better than any other make.


Bob
MY96 5 door WRX Sti
FGR exhaust and K&N panel


[This message has been edited by Bob Rawle (edited 25-04-99).]

Zip

Does anyone know what boost a '93 WRX should be running? Is about 1 bar correct, or is it even higher? I will certainly mention the coil packs when it goes back in on Wednesday. It's quite amazing how much umpf I've lost with the boost restricted to 13psi with a bleed valve. Not happy...

Thanks for all your investigative journalism, everyone - keep it up.
Zip

Zip

Bob - later found that they restricted boost to 7psi, not 13 (a little different, I think you'll agree!) Anyway, they returned everything to normal, and found everything okay to 12psi, with a little 'fluffiness' under very heavy load, as did I for the first few miles. I have had the car all weekend, and it is now diabolical again, tacho leaping to zero instantaneously again on a number of occasions, and power delivery jerky and all over the place under everything other than very gentle throttle. I mentioned the coil packs - PTS are going to get hold of a portable oscilloscope from a mate at Bosch, and see if that shows anything up. As an aside, should I be concerned that the Ramair oil might be getting in somehow, as mentioned in the Polyomer thread??

I shall keep you posted - BOB RAWLE - any more developments??

Regards,
Zip

Bob Rawle

Did they actually do anything ? Its been hot this weekend so any weakness would have been made worse. My car is going in to the dealer tomorrow for its "fix". They've got coil packs and a new knock sensor to fit plus the boost control will be put back to normal. I'm keeping my fingers crossed but since I closed up my plug gaps I've been running 1.1 bar (16 psi)boost with absolutely no problems. This was set using a bleed valve to 0.7 bar initially but I've increased it my self. Not max I grant you but a pretty significant improvement over 0.7 bar.I'm still convinced that an oscilloscope would not pick this up due to the fact that there is no place to pick up for the measurement. The other interesting point is that since tweaking the gaps my fuel consumption has improved by 3-4 mpg !!

Will keep you posted

Bob

Fred

Zip,

It seems we got the same symptoms, and always not fix the problem...

Yesterday, we have just try 4 another coils but no way...
I'm losing my mind, it's not under warranty but I'm lucky that the guys has the same car and put directly his own parts for testing.

Waiting for new idea or info...
Thanks

Bob Rawle

I've posted my latest update on a new thread titled "Engine misfire update and boost guage" for those interested.

Bob