Intermittent Misfire

[andywaddy]

Hi all,

Bit of an issue... I have an intermittent misfire on Cylinder 5. I've changed the plug out as well as swapping coils which lead to no change. The car is a 16 plate performance edition with 6k miles.
I can't replicate the misfire regularly but it tends to happen before the car has reached operating temp and then will behave perfectly when hot and then won't miss a beat. Any ideas?


I've attached a recent VCDS readout if it helps:

01-Engine -- Status: Malfunction 0010
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
10-Park/Steer Assist -- Status: OK 0000
14-Susp. Elect. -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
1B-Active Steering -- Status: OK 0000
22-AWD -- Status: OK 0000
28-HVAC, Rear -- Status: OK 0000
30-Special Function II -- Status: OK 0000
36-Seat Mem. Drvr -- Status: OK 0000
3B-Sensor Elect. -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: OK 0000
55-Headlight Range -- Status: OK 0000
5F-Information Electr. -- Status: OK 0000
62-Door, Rear Left -- Status: OK 0000
65-Tire Pressure -- Status: OK 0000
6C-Back-up Cam. -- Status: OK 0000
6D-Trunk Elect. -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
85-On Board Cam. -- Status: OK 0000
BA-Motor Mounts -- Status: OK 0000

-------------------------------------------------------------------------------
Address 01: Engine (------CWUC)

3 Faults Found:
13432 - Fuel Pressure Sensor (G247)
P119A 00 [096] - Malfunction
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 9336 km
Date: 2016.06.23
Time: 21:18:57

10203 - Random/Multiple Cylinder Misfire Detected
P0300 00 [096] - -
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 9336 km
Date: 2016.06.23
Time: 21:18:57

10595 - Cylinder 5
P0305 00 [096] - Misfire Detected
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 9336 km
Date: 2016.06.23
Time: 21:18:57

Readiness: 0000 0001

[CH3OH]

Do you have sw on the car or not ?
Mine has done it twice... Also a '16

This is not a unique issue on cars with sw from what I have gathered.

[Leo-RS]

What fuel are you using?

Are you running tuned? If so, MRC recommend a plug upgrade.

[andywaddy]

Do you have sw on the car or not ?
Mine has done it twice... Also a '16

This is not a unique issue on cars with sw from what I have gathered.

It was previously tuned by MRC but this was causing it to misfire every single time it was pushed so we agreed to put it back to stock whilst I try to get to the bottom of it.

When tuned it would always misfire if you pushed it slightly before it had got to temp and then also occasionally from 4th to 5th gear on WOT.

When stock it'll only ever log a misfire if you push the car slightly before it's reached operating temp. After that, it's runs like a dream.

I put an oscilloscope on the coils today and the one in cyl 5 was coming back with a slightly lower voltage reading than the others but like I said, I did swap the coil from a good cylinder previously so THAT rules that out surely?

[andywaddy]

What fuel are you using?

Are you running tuned? If so, MRC recommend a plug upgrade.

It always runs on Tesco 99 and nothing else. I was told this was the best?

Please see above re tuning. I spoke with Doug previously and I don't recall him ever wanting to change plugs even though I have seen it previously mentioned on here. If it were plus though, wouldn't it affect more than just one cylinder?

Thank you for the replies by the way, it's much appreciated.

[Paulm]

I have logs somewhere Will see if I can dig them out. cylinder 4 and 5 are the most noisy in terms of knock (or is it 3 and 5 lol need to find those logs). These high compression high boost cars can be tricky re misfiring. As you say it maybe just that cylinder 5 coil is underperforming. not an easy one to diagnose. Swap number 5 out with another cylinder and see if the misfire follows?

[andywaddy]

I have logs somewhere Will see if I can dig them out. cylinder 4 and 5 are the most noisy in terms of knock (or is it 3 and 5 lol need to find those logs). These high compression high boost cars can be tricky re misfiring. As you say it maybe just that cylinder 5 coil is underperforming. not an easy one to diagnose. Swap number 5 out with another cylinder and see if the misfire follows?

That'd be brilliant if you could, thanks.

Just to make 100% sure, I'm picking up a brand new coil this morning so we'll see how that fairs. The most annoying thing is the fact nothing is easy to get to so doing something as simple as swapping coils about takes a lot longer than it should!
I wouldn't even bother looking into this further if I wanted to keep the car stock as it doesn't pose a massive issue but I want it back to circa 700bhp lol.

[Paulm]

I am offshore just now. Will see if I can direct the wife to the logs location. Wont be easy

[doodlebug]

This may be a stupid question, but have you taken to dealer or is that goose cooked as you've had a map?

Does it misfire and go to limp or just intermittent misfire?

[andywaddy]

This may be a stupid question, but have you taken to dealer or is that goose cooked as you've had a map?

Does it misfire and go to limp or just intermittent misfire?

Not been to the dealer as yet, the reason being that I wanted to expel the common misfire causes i.e. coils/plugs etc first as it's just easier than losing my car to them for a few days. Plus, as sad as it is, a part of me quite enjoys the fault finding!
Of course, if I don't get anywhere, the dealers will be the next stop.

No limp mode, just misfires (feels like it's hit the limiter for a second) and then carries on just fine. The CEL flashes for about five seconds and then disappears.

[RS6chris!]

This may be a stupid question, but have you taken to dealer or is that goose cooked as you've had a map?

Does it misfire and go to limp or just intermittent misfire?

This

16 plate car? Why haven't you been back to Audi?

[Paulm]

This may be a stupid question, but have you taken to dealer or is that goose cooked as you've had a map?

Does it misfire and go to limp or just intermittent misfire?

This

16 plate car? Why haven't you been back to Audi?

Previously remapped?? Depends how it was put back to standard?? If MRC put it back using the 100% button be interesting to actually prove it works or not.

[RS6chris!]

Let us know how you get on with Audi.....

Put this "can they detect a map" myth to bed once and for all?


Good luck mind...think your gunna need it.

[CH3OH]

I have a sneaky feeling it has to do with the cyl on demand. The two times mine did it, the car was about to go into 4 cyl mode and I accelerated hard.
I have up rated plugs for the record.
I have no faith that a dealer would find this error.

[andywaddy]

Can somebody with VCDS do me a massive favour and look at the number of misfires on each cylinder for their own car please? Mine are as below and I'm just curious as to what others are getting...
As you can see, cylinder 5 is the where the party is at...