help! smoke, missfire and popping.

[Briggsy]

got a strange problem with my avant that has raised its ugly head after spending a small fortune on other bits.

it all started yesterday, i went out in it and all was fine, didnt miss a beat but when i went to use it again after it had been sitting in the heat it started to miss so i went up the road to clear it but stopped at the lights and the biggest amount of blue smoke started to pour out of the back, thought id screwed something but after about 2 minutes it cleared but still missed, when i got home i thought i would try some other coils donated by jon441cc but no difference!
what do you think?
just to add i have had the 1.8t coil change but it has never been a problem until now!
when having this problem it doesnt want to idle + i never have this problem when the engine is cold.

thanks in advance.
jose.

[Briggsy]

anyone?

[UrS4boy]

Blue smoke has nothing to do with coils, stock or 1.8t coil packs. Blue = oil so I would check your plugs to see if any of them are oil fouled. Perhaps a head gasket issue. Otherwise, something haywire with the crankcase ventilation system control valve (not blowing or sucking as the case may be). OR your turbo to intercooler hose has a puddle of oil in it that got sucked up into the air stream = turbo seal problem.

Or....???

[S2central.net]

Good suggestions there. Blue is always oil alright...

Check all the plugs and do a compression test on each one - disconnect the CMP sensor so it doesn't try to fire - full throttle with the plugs out and spin on the starter until the compression guage peaks. You are looking for differences between each cylinder as opposed to specific values.

A check of the PCV hoses would be good - make sure nuthin is blocked or open to atmosphere.

A little oil inthe intercooler is sadly normal enough due to the way these engines allow blow-by oil vapour to go full circle. A teapspoon or two of oil in the intercooler is pretty normal for a high miler unless it has a catch/cyclone tank mod.

[Briggsy]

thanks for that guys will check PCV aswell as i can tomorrow! the problem only occurs if it has been on a run and then left to sit in the heat, would a head gasket failure then cause missfire?

[220bhp]

Yes it can,I'm afraid,moisture leaks into the cylinder under pressure and fouls a spark plug, hense missfire on startup until it clears.

[4WheelDrifter]

Head gasket failure normally results in steam (white smoke) coming from the exhaust. Also the coolant system can become pressurised from start-up, which can lead to coolant being forced into the cylinders. The car can then missfire from start-up, and gradually clear as moisture is driven from the cylinders.

It's sounds more like a PCV blockage as pointed out above.

[Briggsy]

another couple of questions for you guys!
would a pcv problem cause missfire?
i had the same problem today it would not idle, so out of interest i pulled the idle control valve plug out and it stopped the car from stalling, is this normal?

[Briggsy]

just a little update for you guys. my above problem has turned out to be a faulty maf, it wasnt doing its "burn of cycle" after ignition had been turned of so with help from vagparts i bougth a RS2 maf and have now fitted it with no problems.

jose

thanks to jon441cc for lending me his maf for a while! you should get it back soon.....pal.