Not sure!

[stevieyid]

Right another hard to explain problem. I was coming home last night and decided to open her up in second on the last bit of straight road b4 my house and i had what i can only describe as a sort of misfire. It boosted fine but then it stuttered and even the the sound coming out of the exhaust changed. I tried it again tonight and it happens a little in second but not as aggressive. I have experienced overboost protection and it does not feel the same as that. What do u think? Could it be a boost leak? Cheers

[Ross]

Steve,

I'd check for a leak; it could be - I had this problem occurring and it turned out that 1. My PSV was very dodgy and 2. It was probably caused by the £5 of emergency ****** 95Ron I put in (have an MRC remap for 98ron) that suddenly made it quite noticeable.

I've had a little hesitation again tonight actually; around 1.2.bar - was gone once she hit >3500rpm. Wonder if a plug's loosened up again - could this be a cause?

Was it violent, or more like a subtle hesitation and slight loss of power? You coming to the garage meet?

Cheers
Ross

[stevieyid]

wasnt violent mate just seemed to ease of and the exhaust made a blowing sort of noise rather than powerful roar u get at WOT. Would love to go to the garage meet but i am working Sunday now and Saturday os football day. Could be the fuel i have put in ten pound of esso 97 RON and then 10 pound texaco 97 RON which i no are rubbish fuels but thats all i could get. I dont seem to or have not yet got it in 4th upwards.Thanks for your help

[stevieyid]

What is the PSV again?

[Ross]

Good question.. somethingy-something-valve I'm guessing.

It's part of the breather system, at the back of the engine bay; afaik it lets air + oily **** into the engine to be burned off, but disabled flow in the opposite direction. When it dies, you get flow backwards through the system which equates to a monster boostleak...

I'm sure someone can give you a much more accurate, technical explanation though!

Cheers

[stevieyid]

Could be. I swear i hear whistling noise that i didnt used to hear but that could be me looking for a noise. Just hoping its not a sign the turbo is on its way out. May book it in for a health check at MRC and see if they can find anything. Any other suggestions on what to check? Cheers

[Jon441cc]

Have you checked the rubber boots on the coil packs which go over the spark plugs to see if they are okay.

[T2Andy]

mine does it on crap fuel it doesnt want to rev passed a certain point ,seems to hold back missing slightly but its only occational.

[stevieyid]

It could be the fuel then. Usually i put tesco 99ron in as thats what i had in it when i had the remapp. Ill put that back in it and see if it still happens

[S2central.net]

Good question.. somethingy-something-valve I'm guessing.

It's part of the breather system, at the back of the engine bay; afaik it lets air + oily **** into the engine to be burned off, but disabled flow in the opposite direction. When it dies, you get flow backwards through the system which equates to a monster boostleak...

I'm sure someone can give you a much more accurate, technical explanation though!

Cheers

Its PCV = Positive Crankcase Ventilation system to be pedantic

More or less as loosely described above. Its part of the air plumbing which allows crankcase fumes to be ingested by the engine when under vacuum... or dumped into the MAF hose when the engine is boosting - there is also vacuum on the input side of the compressor. Also means your turbo sucks the crappy crankcase fumes and oil mist into the air intake - bad for a clean mixture and bad for air temperatures... Its why the intercoolers fill up with oil over time - not good.

Paul