Bad misfire under boost

[Welly]

I'm getting a bad misfire under boost in the S3.

It only started yesterday on the way back from crimbo shopping, went to over take something and she had a bit of a stutter. Put it down to one of those things and carried on home. Worse today, was bad on the way to work, and has now developed into a bad misfire as soon as you get anywhere close to full boost.

VAG COM has thrown a 16514 DTC, which is Oxygen (Lambda) Sensor B1 S1: Malfunction in Circuit - intermittent.

This code has been there for a little while now, and i thought it strange that it would start causing problems all of a sudden...

Any ideas good people, before I am forced to burn it?

 

[s3gav]

mine did the same awhile back turned out to be coil pack though i never checked for a fault so may be something else on yours

 

[S3 HODGE]

Most likey a Coilpack as there very well known for failing after having the remap on the S3's.... or ive heard of the MAF giving these problems?

If it is the coilpacks it maybe a better idea to bite the bullet and get all four or you may find you will be "chasing your tail". Also buy the Genuine Coilpacks there around £30 each from TPS,GSF etc....
Hope this helps.

 

[Dani_B19]

Mate you aint having no luck are you. Hope you get it sorted. Said there wasnt sumet dodgy about it though.

 

[<tuffty/>]

Does it happen on part throttle?

Have you logged for misfires?

Is the misfire always there during idle, part throttle and under full load?

If the lambda is playing up then fuelling could be all over the place... could be dumping fuel under boost and giving you the misfire...

Try logging blocks:
001 - will tell you how much fueling the ECU is adding/taking away
031 - will tell you AFR
115 - requested boost v actual

and check 032 after a run to see what the adaption values are...

<tuffty/>

 

[Welly]

Mate you aint having no luck are you. Hope you get it sorted. Said there wasnt sumet dodgy about it though.

Think it's a coil to be fair, and if it is, it's just one of those things!

 

[Welly]

Does it happen on part throttle?

Have you logged for misfires?

Is the misfire always there during idle, part throttle and under full load?

If the lambda is playing up then fuelling could be all over the place... could be dumping fuel under boost and giving you the misfire...

Try logging blocks:
001 - will tell you how much fueling the ECU is adding/taking away
031 - will tell you AFR
115 - requested boost v actual

and check 032 after a run to see what the adaption values are...

<tuffty/>

No miss under idle, good as gold... I'm going to take it out in a bit and see whats what. Watch this space.

Also, no misfires logged earlier in the engine fault codes.

Got a copy of VAG COM 409 handy, are the measuring blocks the same?

 

[Dani_B19]

Well i hope it is mate.

 

[Sandip]

Sorry to sound a little basic, you might just need a new set of plugs, when mine was missing under boost last year i ended up changing loads and in the end all it wanted was plugs

 

[<tuffty/>]

No miss under idle, good as gold... I'm going to take it out in a bit and see whats what. Watch this space.

Also, no misfires logged earlier in the engine fault codes.

Got a copy of VAG COM 409 handy, are the measuring blocks the same?

Yeah, should all be the same... coil packs usually misfire or lumpy idle...

Private road, third gear from 2k rpm to redline... usual story

<tuffty/>

 

[Welly]

All sorted

Took each pack out in turn and gave it a bit of love. A bit of corrosion on the electrical connector on cyl 3 I believe was the cause (must of been - wet fuel still on the spark plug), still, all good now. WD40 and a bit of 800 grade wet and dry. Did all of them for good measure. Problem gone.

*Big Sigh*

 

[S3 HODGE]

Ahh good man. Car must of been sat around for a bit before you bought it?

 

[Welly]

Ahh good man. Car must of been sat around for a bit before you bought it?

Yes, I believe it has been for a substantial period of time. Poor old girl

 

[S3 HODGE]

Just give her a good service and a nice fresh tank of fuel and she will treat you well
Godd buy tho mate, I heard how much you payed for it!

 

[Welly]

Cheers dude, thats exactly what I plan to do. I only run my cars on V Power or Tesco 99 because it makes such a difference I think. Plus much cleaner burn.

Just ordered all servicing kit for her as well - so that will be a job for just before Xmas!!

 

[S3 HODGE]

Good stuff, Yea ive always run mine on V-power! Seems to burn quicker but well worth the few extra pence

 

[Welly]

To be fair, when I tickle it around, I get better MPG on V Power. Problem being I never tickle it anywhere

 

[Grale1]

Sorry to drag this old thread up but Last Thursday I went to Phil millers to have some littlr niggles cleared up and whilst there we changed the actuator for a bbt 12psi one took it out and it was stuttering under boost etc, gauge showed it was going to 15psi. Know I've had a k04 conversion done on it with the usual bits, wellycooler, relentless v1 relentless 3" DP decat, b5 tip etc etc. Phil checked it on vcdsand nothing really came up. Driving the car yesterday and it was running good, today however it just isn't happy does not want to boost at all misfiring all time, would I be right in thinking coilpack ?

 

[badger5]

coilpack,plugs, insufficient fueling, actuator too much for map etc etc... and and all of them could cause it

 

[Grale1]

Cheers bill, yes you did say fueling to me the other day stock map running on actuator pressure. Was fine yesterday and today it's having a proper hissy fit lol.

Si