sc00bylee

dont tend to use the car that much, anyway after a very hard launch up to 7k in first this afternoon i seem to have developed a pretty bad misfire while on boost, So much so it seems be from 3k onwards.
Just checked the plug gaps and they seem fine.

Its a MY97, any ideas?

sc00bylee

forgot to say, checked all intercooler pipework and that seems fine.

if there was a crack in the black plastic MAF to turbo pipe under the manifold would this cause the problem? not that i know of one- just trying to think of all possabilities.

Just seems strange as it was perfectly fine this morning now theres pops and flames from the exhaust...

Jolly Green Monster

iTrader: (4)

compression test time..

could be cambelt jumped or you have piston / valve damage..

sc00bylee

great, just what i didnt want to hear, what makes you think its that bad simon?

Jolly Green Monster

iTrader: (4)

although loss of compression usually is fine above 2k and not good on idle.. so perhaps i am wrong..

intercooler piping all okay?

perhaps I am putting major misfire and 7k launch together and it is not that bad..

sc00bylee

well it idles fine, you can drive it fine as long as its totaly off boost.

I wouldnt nomaly drive like that, lets just say it was either that or get t-boned by an audi.

Any one with a compression tester in the York area? supose i should check that first really.

sc00bylee

intercooler pipework seems ok simon, is it worth trying another coil pack?
is there anything i could check on the FC commander?

Jolly Green Monster

iTrader: (4)

when you say major misfire if it like a brick wall? fuel cut?

sc00bylee

no its not like brick wall, it still pulls, just jerks pops and bangs all the way through.

Anger

iTrader: (4)

Mine was driving like that when i got the cone filter wet, any chance yours has got wet lately mate

Saying that it only lasts for about 5 mins

Did it show anything much on the knock on the FC commander ?

Harper1

Maybe a coil pack? I had the same type of bother in my 96 sti. It started after I fitted a decat, the spark kept blowing out and the car backfired alot on boost. 4 new coil packs solved the problem!

Kyle

sc00bylee

after the launch the knock was at 46, nowhere near that since then.

Anger

iTrader: (4)

It was only when i ragged it wet that i had the problems, driving it normal it felt fine and when it misfired and popped it showed a 50 on the knock and normally i dont even get more than 17

Jolly Green Monster

iTrader: (4)

what is the boost on the commander at the time?

sc00bylee

filter was deffo dry when i checked the plug gaps, may stick a new set of plugs in and try a coilpack.

sc00bylee

peak boost was 1.55 bar on the AVCR simon

sc00bylee

update- took it for a quick spin this morning, it seems to get worse the warmer the car gets.

Does this suggest anything?

Andy.F

Try it on the low boost setting, if the misfire clears then its probably coilpack/lead/plug related.

If it misfires as soon as you come on boost then most likely to be intercooler pipework, especially after an aggressive launch at full chat, it can tug the pipework as the engine rocks under load. Sometimes it can be difficult to notice if a pipe has just slid partway off.
Also check the BOV and FPR signal lines.

Andy

sc00bylee

will do, thanks andy.

Rvizela

it does seem to be a coil issue, coils seem to be more noticable when the car is hot, but ye try that...