2.0T - still misfires when colder

[vtraudt]

Car is now (again) showing misfires on all 4 cylinders.
Started to occur when morning temps dropped below 30 over the last 2 days.

Recently done;
- carbon build intake valves (VERY bad build up; misfires, barely starting)
- PCV valve
- new coils
- new plugs
- rear main seal

Still has oil leak at timing cover.

Unrelated: DSG service done.

When car was brought to me today, it was warm, engine running and sounding perfect, no misfires. Yesterday, (not so) cold start, misfiring, CEL on.

What else can I check and troubleshoot to determine the cause of the misfires?

110k miles on the car.

[mecg]

What are you getting for codes?

[vtraudt]

What are you getting for codes?

Misfire random:

000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 000 - - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 7
Reset counter: 255
Mileage: 183529 km
Time Indication: 0
Date: 2019.14.19
Time: 11:06:09

Freeze Frame:
RPM: 906 /min
Load: 32.5 %
Speed: 0.0 km/h
Temperature: 6.0°C
Temperature: 0.0°C
Absolute Pres.: 980.0 mbar

000769 - Cylinder 1
P0301 - 000 - Misfire Detected - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 7
Reset counter: 255
Mileage: 183529 km
Time Indication: 0
Date: 2019.14.19
Time: 11:06:09

000771 - Cylinder 3
P0303 - 000 - Misfire Detected - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 7
Reset counter: 255
Mileage: 183529 km
Time Indication: 0
Date: 2019.14.19
Time: 11:06:20

Freeze Frame:
RPM: 900 /min
Load: 32.5 %
Speed: 0.0 km/h
Temperature: 8.0°C
Temperature: 0.0°C
Absolute Pres.: 980.0 mbar

000772 - Cylinder 4
P0304 - 000 - Misfire Detected - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 7
Reset counter: 255
Mileage: 183529 km
Time Indication: 0
Date: 2019.14.19
Time: 11:06:20

000770 - Cylinder 2
P0302 - 000 - Misfire Detected - Intermittent
Freeze Frame:
Fault Status: 00100000
Fault Priority: 0
Fault Frequency: 7
Reset counter: 255
Mileage: 183529 km
Time Indication: 0
Date: 2019.14.19
Time: 11:06:20

Freeze Frame:
RPM: 900 /min
Load: 32.5 %
Speed: 0.0 km/h
Temperature: 8.0°C
Temperature: 0.0°C
Absolute Pres.: 980.0 mbar

[kehubbard]

Considering what has already been done it seems plausible that you should be looking for a fueling issue. Maybe the injectors are also nasty with carbon and can't flow enough when the engine is cold and in the enrichment mode.

[chiefl]

Just checking with u guys if u found the issue? I am getting the same exact codes. I have a 2009 A4 2.0t.


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[vtraudt]

Update: through further searches, I found finally became aware of the carbon build up issue on the direct injected cars, specifically the Audi VW 4 cylinder 2.0T.
Removed intake, and found intake valves CAKED with carbon build up.
Cleaned.
Running fine.

Since then, have done several intake cleanings on 2.0T in my network who should symptoms, and as preventative maintenance.

[chiefl]

Good info. I know my rear main is leaking really bad. About how much did that run u?


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[vtraudt]

Good info. I know my rear main is leaking really bad. About how much did that run u?

THAT (rear main seal leak) was another cause for misfire (2010 A5 2.0T). What mainly opened my eyes to that possibility was a leak test with a smoker (couldn't find anything from the top, but when getting underneath the car/engine, I found lots of smoke coming from transmission bell housing area); never thought of a rear main seal leak as a vacuum leak. Change rear main (shop around $1,500) fixed those misfires.

Intake valve cleaning: what I read, around $400-$600 at shops.

[chiefl]

Interesting. Thx


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[Nczcar01]

I have heard some stories about upgraded PCV due to older versions causing rear main seal to blow....resulting in misfires.

[chiefl]

Ok interesting. I was planning on changing the pvc just as a precaution for future problems. Taking the car to a shop tomorrow to get the rear main done.


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[chiefl]

Just an update
I had the RMS done and changed the PVC to include an intake valve cleaning. The car how ever continues to have a misfire in cyl 2&4. The shop is keeping it over the weekend to do a smoke test. Hopefully its something minor. Im done throwing money at this car


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[chiefl]

So for the RMS-$1600
Valve cleaning-$500
Smoke test-$200


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[vtraudt]

Just to be sure, you already did check the obvious: coils and plugs?
If you have vagcom, watch block 015 and 016 (misfire counter per cylinder).
If predominantly 2 and 4, switch coil 2 to 1, 1 to 2. Repeat and check misfire count.
Then plugs.

With cleaned valves, rear main seal and no leaks (smoke test), PCV done: not sure where else to look really.

I assume misfires when when cold and idle? And not so much when warmed up, and driving?

[chiefl]

Coils and plugs r brand new from ECStuning. Lets see what smoke test results r. They already swapped coils and that didnt change. Last things i can think of is the manifold or the injectors.


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[persaudnav]

Sounds like injectors.

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[chiefl]

Shop did a compression test and got 90 psi from cyl 2 & 4.


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[Nczcar01]

Shop did a compression test and got 90 psi from cyl 2 & 4.


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Check this thread out. Sounds like some similarities.
http://www.audizine.com/forum/showth...mpression+test

[chiefl]

It does. Might be worth a look in the valve cover.


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[nizmosx]

Its most likely your injectors. i was having the same issue. Missfires on cold starts, then runs fine after being warmed up. Swapped injectors, problem gone.

[chiefl]

Dont see what injectors have to do with low compression??


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[nizmosx]

^^^ i was responding to the OP issues not yours. sorry for confusion.