Misfire detected DTC

[Quattrodave]

Morning all,

Two days ago I had a very rough and not happy A8 (4.2 FSI). On pulling the codes I got P0024 - B Camshaft position timing over advanced - Bank 2. It also stated misfire on cylinders 5, 6, & 8.

I had only just left home so quickly turned around and headed back. After a few restarts the engine ticked over fine, I cleared and then reran the codes and all came up clean so off I went, 15 or so miles no problem.

Then last night it came back again, only this time misfire on cylinder 8 only and P0024.

Same this morning. rough as hell at idle but revs fine, no lumpyness or such when under way. There's a lot of clicking coming from the passenger footwell too, relay/solenoid type clicking - presuming these are linked?

In peoples experience would the above suggest that the camshaft solenoid in bank 2 need replacing, if so, how much are they and is it a diy job?

Thanks

[Mechcanico Lee]

Yes could be sticky timing control solenoid , if its staying open which will advance the cam this would cause rough running on one bank of cylinders like the fault codes were backing up .

With vcds go into solenoid activations ,there will be 4 i think on that engine , listen for a positive click from each sol. ....its not very loud just like a light clicking sound

I had similar on audi TT , in some cases an engine flushing agent and oil change may just un stick the build up in the actuator body.

Forte do a good engine flush , you havent lost anything if it doesnt work ,just gained a cleaner engine , if it doesnt work yes looks like replacement of the solenoid is first port of call .

[Quattrodave]

Originally Posted by Mechcanico Lee

Yes could be sticky timing control solenoid , if its staying open which will advance the cam this would cause rough running on one bank of cylinders like the fault codes were backing up .

With vcds go into solenoid activations ,there will be 4 i think on that engine , listen for a positive click from each sol. ....its not very loud just like a light clicking sound

I had similar on audi TT , in some cases an engine flushing agent and oil change may just un stick the build up in the actuator body.

Forte do a good engine flush , you havent lost anything if it doesnt work ,just gained a cleaner engine , if it doesnt work yes looks like replacement of the solenoid is first port of call .

Took it to a local garage (new to me as my usual one is busy til next week) and they've suggested new coil packs for the three that are misfiring and then go from there.

My question is would a solenoid in need of replacement cause three cylinders on one bank to misfire or do they genuinely need coil packs?

Car was under audi extended warranty until April this year so I would have hoped everything done until that point was top notch?!

[Norretal]

Originally Posted by Quattrodave

Car was under audi extended warranty until April this year so I would have hoped everything done until that point was top notch?!

Not necessarily, I refer you to this can of worms below..........

http://forum.a8parts.co.uk/showthread.php?t=10436

Hope it's an easy, cheap fix for you. I personally would wait for a second opinion before buying coil packs, surely their diagnostics would have given them more information to go on than that? Sounds very much like some clutching of straws going on, unless of course they gave specifics as to why they are suggesting coil packs?

[Quattrodave]

Originally Posted by Norretal

Not necessarily, I refer you to this can of worms below..........

http://forum.a8parts.co.uk/showthread.php?t=10436

Hope it's an easy, cheap fix for you. I personally would wait for a second opinion before buying coil packs, surely their diagnostics would have given them more information to go on than that? Sounds very much like some clutching of straws going on, unless of course they gave specifics as to why they are suggesting coil packs?

They did full diagnostics using auto com

They mentioned new coil packs due to

P0305
P0306

P0308 fault codes all saying misfire detected - permanent

[Norretal]

Originally Posted by Quattrodave

They did full diagnostics using auto com

They mentioned new coil packs due to

P0305
P0306

P0308 fault codes all saying misfire detected - permanent

Fair enough, they're responding to the codes they've viewed then. My concern was that I had a "shudder / misfire" at low revs on my D2 and was convinced it was the gearbox as it shook the car, turned out to be electronic and caused by fouled lambda sensors due to it not being driven enough.

Hope you get sorted, there are plenty of helpful people on here that can advise better than me

[Mechcanico Lee]

If bank 2 is cylinders 5 6 7 8 and camshaft B is also bank 2 i think its a mad coincidence that all coils can go down on one bank .

If the cam stayed advanced on that bank the whole bank will run rough and cylinder missfire detection count will be triggered , looking at the orginal codes cylinder 7 is not there .......bit strange but i would follow the codes for that cam position .

Swap coil sticks from one bank to the other , if the codes stay on 5 6 7 8 sort of proves its not the coils , if it transfers ..... yes sounds like coils

Also when running in vcds data blocks you can see where cam advance is by means of degrees , if it has a cam sensor on every cam this is good because you could see all 4 cams ......some quad cam stuff only have a cam sensor on one cam per bank ....so for instance the exhaust cam could be stuck advanced but the sensor is on the inlet so the managment wouldnt see it .

[Quattrodave]

Originally Posted by Mechcanico Lee

If bank 2 is cylinders 5 6 7 8 and camshaft B is also bank 2 i think its a mad coincidence that all coils can go down on one bank .

If the cam stayed advanced on that bank the whole bank will run rough and cylinder missfire detection count will be triggered , looking at the orginal codes cylinder 7 is not there .......bit strange but i would follow the codes for that cam position .

Swap coil sticks from one bank to the other , if the codes stay on 5 6 7 8 sort of proves its not the coils , if it transfers ..... yes sounds like coils

Also when running in vcds data blocks you can see where cam advance is by means of degrees , if it has a cam sensor on every cam this is good because you could see all 4 cams ......some quad cam stuff only have a cam sensor on one cam per bank ....so for instance the exhaust cam could be stuck advanced but the sensor is on the inlet so the managment wouldnt see it .

Thanks, my thoughts were it wasn't necessarily coil pack related given that the fault started on Sunday with faults on advanced timing (P0024) and cylinders 5 & 8 but then went away after resetting and restarting car (and ran fine for a day and a bit) and then only came back last night with faults on three cylinders, all on the same bank as the over advanced fault.

Good call on the switching coil packs between banks, certainly better than 'guessing' at coil packs at £35 each! I'll mention it to the garage tomorrow and if they don't agree to try that I'll just get on my bike and wait until my local garage is free!

[Quattrodave]

Three coil packs replaced (all on same bank) and all seems well with the car so far. Cam adjuster code hasn't resurfaced so hoping all is good.

[Mechcanico Lee]

3 coils all at once !! Never would of thought ...