Fustrated by misfires (w/ codes and troubleshooting steps that I've taken)

[angry12v]

I just bought another S4, and it was misfiring when I got it. CEL was on, and at one point it was even flashing at idle...

Scanned and got these codes:

4 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 ** 35-00 - -
16686 - Cylinder 2 Misfire Detected
P0302 ** 35-00 - -
16700 - SAE: Engine Misfire Detected on Startup (First 1000 Revolutions)
P0316 ** 35-00 - -
16690 - Cylinder 6 Misfire Detected
P0306 ** 35-00 - -

1. Swapped coils on cylinders 2 & 3, and 5 & 6. No change. All the same codes.
2. Swapped the positions of the ICM's. No change.
3. Checked the gap on the plugs and it was correct at .028. Removed the NGK plugs and replaced them with Bosch F5DP0R. No change...
4. Pressure tested and the only leak I could hear was from the typical brake booster line at the "T". Covered the outside with JB weld, no more leak.
5. Took the throttle body boot off to inspect it, and didnt see any tears or cracks. Noticed one of the vacuum lines to a diverter valve was in bad shape, so I replaced it.

The car seemed to run better, no CEL but still a little rough. Scanned and got these codes:

3 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 ** 35-00 - -
16688 - Cylinder 4 Misfire Detected
P0304 ** 35-00 - -
16699 - SAE: Crankshaft Position System Variation Not Learned
P0315 ** 35-00 - -
16689 - Cylinder 5 Misfire Detected
P0305 ** 35-00 - -

Where do I go from here?

Any help would be appreciated, thank you.

[a4_1.8t_01]

Check the grounds on those coils that are bad.

[angry12v]

Check the grounds on those coils that are bad.

ground on the coils?

[NefMoto]

Are there any mods on the car?

[angry12v]

Are there any mods on the car?

completely stock. forgot to mention that in the original post...

[NefMoto]

You could try running with the MAF disconnected to see if it is related to the MAF or O2s, but that is a long shot.

I don't like this error code: 16699 - SAE: Crankshaft Position System Variation Not Learned

Does that error code stay around after driving the car for a while?

[angry12v]

You could try running with the MAF disconnected to see if it is related to the MAF or O2s, but that is a long shot.

I don't like this error code: 16699 - SAE: Crankshaft Position System Variation Not Learned

Does that error code stay around after driving the car for a while?

I will try running without the MAF tonight and see what i get for codes.

I don't like that code either... and I cant find any info on it. It seems to only appear after driving it around. When I just let it idle, it only comes up with the misfire codes.

I have 6 new coilpacks, a new crankshaft position sensor, and new fuel filter on the way...

Running out of ideas.

[ski&drive]

do you access to vag-com?

Log block 112 and see what your getting for the egt's If its doesnt stay at 945 degrees then thats your problem.

As suggested above the Maf and 02's are a good place to start

the crack sensor code could be because its misfiring.

[angry12v]

Block 112 is showing exactly 945 degrees

Watching block 15 (supposedly cyl 1-3) shows misfires that count up fairly slowly. The most I saw was about 40. Most of the time its only showing 3 or 4 before it resets to 0.

Block 16 (4-6) isn't showing any misfires

This is all at idle. Scanned and got the same exact codes as in the original post. Random, cyl 6 and 2 misfires.

Unplugged the MAF and ran it, showed the same misfires on block 15 but no misfire codes. Just the code for unplugged MAF. I'm not convinced though...

[angry12v]

Plugged the MAF back in and got random, cyl 4 and the crank position code again....

[NefMoto]

Verify that your car is idling at correct vacuum using VAG-COM or with a boost gauge. If vacuum is correct, get a remote fuel pressure gauge and check that fuel pressure is 4bar above the intake pressure.

I'm running out of ideas, and I'm not willing to start telling you to randomly replace things. It could be the crank sensor though, and I am not sure how to test that.

[angry12v]

Thanks for the help, I appreciate it.

Ill look into the vacuum. My boost gauge doesn't read vacuum so I guess I need to find it in vagcom measuring blocks?
After that ill have to borrow a fuel pressure tester.

All new coilpacks, crank sensor and fuel filter will be here tomorrow so we'll see if any of that fixes it.

[Aphex350]

Did you ever resolve this?

[angry12v]

Did you ever resolve this?

I never did resolve this and I just got around to messing with it again recently now that the car is out of storage. Sorry for bumping an old thread.

I've just replaced all of the coilpacks, and the crank position sensor. Still have the same codes in the original post, with the exception of the crankshaft position one.

I'm starting to suspect MAF or 02's at this point

[s4boost]

i had the same issue on my car for months. god forrbid you have to go through it, it ended up being a bad cam, the edges of the lobes were rough seemingly from oil starvation, as were the lifters, and there was a very very slight amount of buildup on the valve seats. i you cant find the issue, you may wanna check that. cost about 3,000 to get fixed. pulled the engine, pulled the head, machine shop, new internals, put it back together. PITA

[P0234]

I didn't see any compression tests or anything about you moving injectors around. Also how much vacuum are you pulling at idle?

[themadscientist]

I didn't see any compression tests or anything about you moving injectors around. Also how much vacuum are you pulling at idle?

I'm thinking and wondering the same...

[Ribbie]

Definately a compression check. Got to look up the misfire 101 thread.....

And ya, same as above.

[AWM tuning]

the harness to the coils get really brittle and can cause the ignition coils to misfire i have replaced a few on different vehicles