Missfire

[montyrs2]

Grrrrrr. Had S2 out last weekend for an MOT and it ran as usual with no fault. Parked up all week an this morning I suddenly have a missfire.

Started car and it seemed a bit lumpy, first hundred feet and it cleared it's throat and ran well. During drive to work missfire got more consistant.

I say missfire, no pops or bangs, just a gentle non fire which results in a loss of power, it's smooth at cruising speeds but as soon as you add a bit more gas it's definately not running right. No odd noises or warning lights.

Any ideas where to start? Any common faults?

[Rikki Kitto]

I reckon that could be quite a long list start of with the usual suspects.
spark plugs
coil packs, wiring, connections, plugs etc
POS units
injector
Really help if you could identify which cylinder its missing on 1 or more maybe.

I generally make sure everything has good connections spray a bit of Kontact cleaner on the plugs and joins when engine is off, clean it all up old cars play up easily

[montyrs2]

Plugs are new, might get a chance to try to work out which cylinder is playing up later.

Mostly just wondering if there is a usualy suspect in this or if I need to start at the begining and work from there.

[simon20vq]

boost leak would also give similar symptoms.

[mike74]

If its been damp this last week it might just be needing a good run to get everything hot and dry. WD40'ing everything in sight is also a good idea too though

[UrS4boy]

One missing and hesitation diagnostic

...Any ideas where to start? Any common faults?

If only I got a GBP for everytime that I've posted the missing and hesitation diagnostic link below, I could be retired by now.

Oh wait, ..... I am.

(Follow the hyperlinks within the post as well)

http://forums.quattroworld.com/s4s6/msgs/22611.phtml (written for the C4 UrS4/S6 AAN but adaptable to the S2 and RS2 as well)

[montyrs2]

If only I got a GBP for everytime that I've posted the missing and hesitation diagnostic link below, I could be retired by now.

Oh wait, ..... I am.

(Follow the hyperlinks within the post as well)

http://forums.quattroworld.com/s4s6/msgs/22611.phtml (written for the C4 UrS4/S6 AAN but adaptable to the S2 and RS2 as well)

ha ha cheers

[Cottis]

Is it hesitation on boost or throughout the range. A poor connection on the MAF can be responsible for poor running sometimes and is very easy to unplug, little tidy up with contact cleaner and ensure the pins have not moved away from where they should contact. Always the first thing I try with these cars and has done the trick on more than one occasion.

Hope it is not anything serious.

[montyrs2]

Is it hesitation on boost or throughout the range. A poor connection on the MAF can be responsible for poor running sometimes and is very easy to unplug, little tidy up with contact cleaner and ensure the pins have not moved away from where they should contact. Always the first thing I try with these cars and has done the trick on more than one occasion.

Hope it is not anything serious.

Lets hope nothing serious. Clean bill of health from VRS a few weeks ago so hopefully its nothingmassive, just an electronic component getting upset or damp etc. Tis no worries. I'll find it and fix it, just not sure when as next month is mega busy!

[Error404]

Pull the codes first, go from there.

[Error404]

If only I got a GBP for everytime that I've posted the missing and hesitation diagnostic link below, I could be retired by now.

Oh wait, ..... I am.

(Follow the hyperlinks within the post as well)

http://forums.quattroworld.com/s4s6/msgs/22611.phtml (written for the C4 UrS4/S6 AAN but adaptable to the S2 and RS2 as well)

Dave I read your post, excellent info as always. One thing - may I suggest changing your strong recommendation on the F5DPOR plugs since in the last few years these are now known to have engine killing manufacturing defects?

[Cottis]

Good call. NGK's going in mine when my brakes are being fitted. They are sat on the side awaiting install. Bosch plugs work fine but too many stories to continue risking it.

[montyrs2]

Good news. Turned out to be a loose injector plug. Looks like it's all sorted. Been away for a while so didn't get a chance to look at it before.

[newsh]

Good news. Turned out to be a loose injector plug. Looks like it's all sorted. Been away for a while so didn't get a chance to look at it before.

Nice easy fix, excellent! That's a rarity