Misfire-piston rings
 

After recently finding a faulty neutral diff switch, on replacing this my car was then misfiring at 5 1/2k revs and over:mad: . Got it checked and apprarently cars been running lean on two drivers side cylinders and the piston rings are passing slightly causing misfire at high revs. compression is still over 100psi. garage said it would be at least £1500 to get it sorted and then theirs the question of whats caused it to run lean. garage says it possible dump valve is leaking sucking in air leanng out mix.

Has any one had piston rings replaced and how much did it cost? etc:confused:

is this a reputable scoob garage or a backstreet jobbie?
what year is your car, as it does sound a bit like coil packs. Is the compression within a few psi of each cylinder?
How do they know its been running lean as well?

Get a second opinion from a Subaru specialist.

Mark.

try scoobyclinic at chesterfield mate, top notch

yer i think that i would look into abit more i think, doesnt sound like a compression fault to me.

what Mark said!

i would also be looking at coil packs first if its a pre 96 car.

if you are handy with the spanners take them out and pull the rubber boot off the end but be careful as the plastic usually breaks off.

if this is so then thats your fault.

costs around £240 for a set of packs.

Its a bugeye 2001, wrx, with full exhaust, dump valve, new turbo, fuel reg valve, induction kit, remap all done by graham goode racing

I think he said the compression was 140psi in two cylinders, 125psi in one and around 110psi in other. Apparantly the spark plugs were white on the two low compression cylinders. we tried new maf, and he said he tried new coils and other obvious stuff. I don't think he would make it up as he suggested I sold it and didn't try to make me get it done there. I'd had a service there a while back they specailise in scoobies and do alot of rebuilds for subaru. He's did all diagnosics on it but nothing shows up other than the faulty neutral diff switch which replaced free of charge. :wonder:
Whether the damage was done by driving car with the faulty switch for a month or so:confused:

It drives fine normallly and doesn't turn over quicker than normal, its weird:freak3:

so was it graham goode who told you its the rings and running lean?
If they did the remap then surely its down to them

No gramham goode did all the mods before I got the car their was no signs of running lean when I had it serviced, its only recently been running lean. They gave it a clean bill of health after a service so I don't no whats changed.:confused:

what fuel pressure reg are you using???

And what turbo, and boost ? are you still on standard injectors ?


Mark.

Hmmm.... this is the old "we think it's 'this'...." and you pay for it routine....
Get a second opinion. Your garage are making it sound like an over-heating/ lean problem (drivers side cylinders.. white plug).
So, after an electrical fault, your car developed a missfire? "faulty neutral diff switch which replaced free of charge" Why?

Cars running around 15psi boost, Standard injectors as far as I know. I'll have to check out what turbo and pressure reg in some daylight. Any idea what fuel pressure I should be running at. I'm starting to wonder if its something simple like fuel pump as seems to purge for sometime on starting the car.

The orignal problem started when I let wife drive car to save bulking on the mileage(my first mistake lol), when I drove it a couple of weeks later(properly) was when I noticed it wasn't running right and orignally it was over boosting to around 18psi and I found split hose on boost solenoid to the air inlet, got this replaced and things never been same since. Whether this over boosting did damage and diff switch problem was always there and misfiring just highlighted it? :confused:

Also when I bought the car had engine management light on which was a faulty exhaust temp sensor which I looped out with a resistor don't no if this could cause any probs?