Engine idling rough/ RPMs fluctuating

Hello Everyone,
Im posting this on behalf of a friend. He is having Idling/RPM fluctuating issues and misfires. See below for a synopsis of his issue. Also see engine codes below. Any help and or assistance would be greatly appreciated.

"2009 Volkswagen GTI

81k Miles

2.0TSI

Issue:
When I start the car the RPMs shoot up to about 2k and stay there for a while then slowly drop down to 1k. Once it gets to 1k it starts to flutter for about 10 seconds randomly. And then when I am driving and I shift the car into neutral it goes from 1k and quickly jumps to 2k and revs there for about 5-7seconds then drops to 1k and starts fluttering again. The check engine light appeared, and when I had it read I got random cylinder misfire codes. I took the car too Volkswagen to have them run a diagnostic on it and they came back and told me that there was a leak in the rear crankshaft seal (rear main seal) and that was causing the PCV (positive crankcase valve) to malfunction which is creating a vacuum leak which is causing the high revs and fluttering. I replaced the PCV and that helped the rpm spike and fluttering while the car is idling, but I am still having the same issue with the RPM spike when I shift in to neutral. I took it to a guy that does a lot of work on VWs and he cleared the codes and that caused the motor to start shaking and running very hard, it also started making a Knocking noise that it was not making before. Then he pulled the codes again and got a “leak in air system” code. The only mods I have done are a Unitronic cold air intake, R8 coil packs, and NGK BKR7EIX spark plugs. Also the intake manifold was replaced by the place I bought it from, about a month and a half ago. Will replacing the rear crankshaft seal (rear main seal) put a stop to that? Or is there something else I should be looking for?"

Engine Codes that were pulled VIA VAGCOM

Saturday,07,March,2015,15:10:58:38913
VCDS Version: Release 14.10.1 (x64)

Address 01: Engine Labels: 06J-906-026-CCT.clb
Control Module Part Number: 1K0 907 115 AE HW: 1K0 907 115 AA
Component and/or Version: 2.0l R4/4V TFSI 0040
Software Coding: 0403010A18070160
Work Shop Code: WSC 01357 011 00200
VCID: 69D3C22C40E1E369D9E-803C
5 Faults Found:

008825 - Leak in Air Intake System
P2279 - 000 -
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 130748 km
Time Indication: 0
Date: 2000.00.00
Time: 14:56:48

Freeze Frame:
RPM: 775 /min
Load: 14.1 %
Speed: 0.0 km/h
Temperature: 97.0*C
Temperature: 36.0*C
Absolute Pres.: 970.0 mbar
Voltage: 14.097 V

000768 - Random/Multiple Cylinder Misfire Detected
P0300 - 000 -
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 130748 km
Time Indication: 0
Date: 2000.00.00
Time: 14:57:32

Freeze Frame:
RPM: 759 /min
Load: 14.1 %
Speed: 0.0 km/h
Temperature: 98.0*C
Temperature: 36.0*C
Absolute Pres.: 970.0 mbar
Voltage: 14.224 V

000769 - Cylinder 1
P0301 - 000 - Misfire Detected
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 130748 km
Time Indication: 0
Date: 2000.00.00
Time: 14:57:32

Freeze Frame:
RPM: 759 /min
Load: 14.1 %
Speed: 0.0 km/h
Temperature: 98.0*C
Temperature: 36.0*C
Absolute Pres.: 970.0 mbar
Voltage: 14.224 V

000772 - Cylinder 4
P0304 - 000 - Misfire Detected
Freeze Frame:
Fault Status: 01100000
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 130748 km
Time Indication: 0
Date: 2000.00.00
Time: 14:57:32

Freeze Frame:
RPM: 759 /min
Load: 14.1 %
Speed: 0.0 km/h
Temperature: 98.0*C
Temperature: 36.0*C
Absolute Pres.: 970.0 mbar
Voltage: 14.224 V

001287 - Idle Control System RPM
P0507 - 000 - Higher than Expected. - Intermittent - MIL ON
Freeze Frame:
Fault Status: 10100000
Fault Priority: 0
Fault Frequency: 2
Reset counter: 255
Mileage: 130748 km
Time Indication: 0
Date: 2000.00.00
Time: 15:02:36

Freeze Frame:
RPM: 1340 /min
Load: 11.0 %
Speed: 0.0 km/h
Temperature: 102.0*C
Temperature: 31.0*C
Absolute Pres.: 970.0 mbar
Voltage: 13.970 V


Readiness: 0110 0101

Clearing the code will also reset the fuel trims.....on my R that makes it lightly stutter for a moment while it resets/relearns the idle trim, but it's very fast, just literally a second.

Usually a wavering idle will mean a vacuum leak somewhere. I had that happen to me last summer when the hose I tapped into for my boost leak was leaking real bad after an hour long session with the car popped a nice big hole in it. Soon as I patched it up, it was fine though.

Can you look at things in vagcom? If so, check Engine block 032 to look at fuel trims. Hopefully they're both close to 0 (within +/- 10% is fine I think). Maybe also check readiness and see if your O2 sensors are ok (fuel trim is based on that and the MAF).

Then again, if they said your rear main seal was causing a PCV leak.....I'm not sure how replacing the PCV will fix that. You'd have to replace that seal I'd imagine.

lateapxr said:

Clearing the code will also reset the fuel trims.....on my R that makes it lightly stutter for a moment while it resets/relearns the idle trim, but it's very fast, just literally a second.

Usually a wavering idle will mean a vacuum leak somewhere. I had that happen to me last summer when the hose I tapped into for my boost leak was leaking real bad after an hour long session with the car popped a nice big hole in it. Soon as I patched it up, it was fine though.

Can you look at things in vagcom? If so, check Engine block 032 to look at fuel trims. Hopefully they're both close to 0 (within +/- 10% is fine I think). Maybe also check readiness and see if your O2 sensors are ok (fuel trim is based on that and the MAF).

Then again, if they said your rear main seal was causing a PCV leak.....I'm not sure how replacing the PCV will fix that. You'd have to replace that seal I'd imagine.

Click to expand...

Hmm good point. I just didnt think leaking oil out of the main seal would be causing a Mmsfire you know?

What I'm wondering/imagining is the vacuum leak is causing the computer to skitz out trying to determine "normal" and it's unable to find it (hence the loping idle....it can't settle down). Then, in an effort to get a stoichiometric fuel mixture (natural behaviour of the ECU to protect the motor) it's wildly adjusting the fuel trims up and down to try and match the intake air pressure that it's unable to correctly measure (because of the vac leak).

So then you have either too much fuel or not enough fuel causing misfires.

But take this all with a grain of salt, it's only my half-educated guess at best. If you have VCDS you could also see which cylinders the misfires are occurring on too. That will tell you if it's just one or spread across them all. Chances are, ALL of the coil packs, spark plugs, or injectors didn't ALL die at the SAME time....but fuel trims may cause that I'm guessing.

lateapxr said:

What I'm wondering/imagining is the vacuum leak is causing the computer to skitz out trying to determine "normal" and it's unable to find it (hence the loping idle....it can't settle down). Then, in an effort to get a stoichiometric fuel mixture (natural behaviour of the ECU to protect the motor) it's wildly adjusting the fuel trims up and down to try and match the intake air pressure that it's unable to correctly measure (because of the vac leak).

So then you have either too much fuel or not enough fuel causing misfires.

But take this all with a grain of salt, it's only my half-educated guess at best. If you have VCDS you could also see which cylinders the misfires are occurring on too. That will tell you if it's just one or spread across them all. Chances are, ALL of the coil packs, spark plugs, or injectors didn't ALL die at the SAME time....but fuel trims may cause that I'm guessing.

Click to expand...

Here is the interesting part..after clearing the codes drove around for a bit then re scanned the car he had cylinder 1-4 misfires. Popped the hood and his engine was violently shaking.

bers_mk6 said:

Here is the interesting part..after clearing the codes drove around for a bit then re scanned the car he had cylinder 1-4 misfires. Popped the hood and his engine was violently shaking.

Click to expand...

Were you able to figure this out? Im having the exact same issue? was it a leak somewhere?