still missfiring

[Anees786]

the other day i was drivin my s2 and all of a sudden it started to missfire i thought it needs replacement coil plugs bought them its still miss fireing what should i do next guys im lost i think it might be a possible air leak might be suckin in air

[Keeper of The Kitten]

Seems there are lots of things which cause problems, so annoying.

I had my second air meter (MAF) replaced a week ago (under warranty) and my car was running really well, but it wasn't by last night - though I suspect a heat related problem as it had been running hard and fast earlier before I parked it, and five minutes later I was driving again and it just wasn't right. Heat soaking into the engine bay when the car isn't moving, and it was a warm day - anyone got any thoughts on this?

Air leak sounds quite likely but I will leave it to the experts to decide! Maybe my problem is even an air leak brought about by the temperature rise?

__MDC__

[Anees786]

i think what might have caused mine is that i put CATACLEAN into the ptrol tank of my car and that f**s about with the emissions it might be that ****in its a pain in the **** it only happens once the car is warmed up i think that it could gbe something sucking in air !!

[audiman]

If you had a some air leak then this would possibly lean the mixture enough to cause a misfire.

[Anees786]

i took out the spark plugs to find they been covered with black stuff i think thats down to too a strong mixture what puzzles me is that i put my foot down and thats when it started to miss fire no its like that all the time

[newsh]

Air leak after the turbo when on boost = rich (wasted air) Air leak before the turbo = lean (extra air drawn in after MAF)

Any air leak when off boost = lean.

Lamda will try to correct for this but can onl do so much.

Otherwise could be a prob with MAF (or its connection a few of us have had troubles with this) or the Lamda.

[jubjub]

Air leak after the turbo when on boost = rich (wasted air) Air leak before the turbo = lean (extra air drawn in after MAF)

Any air leak when off boost = lean.

Lamda will try to correct for this but can onl do so much.

Otherwise could be a prob with MAF (or its connection a few of us have had troubles with this) or the Lamda.

If its running rich will you be able to smell fuel ..........

[Anees786]

i m gonna go get the car tuned up see if it has got something to do with emissions. But what is a MAF ?? im gnna put new plugs in there and see what happens then go for a tune up

[audiman]

There arent any settings for a 'tune up'. The car is completely ECU controlled. MAF= Mass Air Flow sensor, its located on the airbox with a big electrical connector on it. Try cleaning the connections with some spray contact cleaner. If that doesnt help then check boost hoses for splits or holes.

[Anees786]

i didnt know s2's have dirstributer caps or rotor arm or have i got it mixed up with something else

[audiman]

The early 3B's had that type of 'old' ignition system, later ABY cars moved onto coilpacks

[Anees786]

i thouht so just bought brand new coil plugs from vag, miss fire is still there starts from 1000 revs

[Doug_RS2]

try changing the power amplifiers - the coilpacks are connected to these.

[audiman]

I would say you have a boost leak somewhere.

[caterpillar]

try to change the lamda,it might gone,then you get very rich with petrol...then you check the ignition switch,low volt to the coilsystem,gives bad sparks