Rough idle after timing belt job

[seattlematt]

I just finished replacing my timing belt and I got a rough idle. Sounds like it misfires a bit at idle. What worries me is that it is accompanied by an intermittent rattling sound somewhere in the back of the engine.
-Once I give it gas it all goes away.
-I double checked the belt timing and the marks are dead on
-I pulled and regapped the spark plugs (were removed during the job)

I will follow up with a video and some VAG. (I have windows7 on my MacBook so VAG-COM is a pita)

[old guy]

Mask sure it isn't something as simple as a loose hose somewhere causing a vacuum leak at idle. The rattling sound may just be the cam chain bouncing a little from the rough idle.

[seattlematt]

Update:
-Compression check: 148,150,147,150 - Seems ok for 115K, I don't think it's a bent valve.
-VAG-COM codes:
BEFORE CLEARING CODES
Sunday, 14 November 2010, 16:35:55

VAG-COM Version: Release 409.1-S



Control Module Part Number: 8E0 909 518 AK

Component and/or Version: 1.8L R4/5VT G 0003

Software Coding: 0016711

Work Shop Code: WSC 12596

10 Faults Found:

17939 - Camshshaft Timing Adjustment: Open Circuit

P1531 - 004 - No Signal/Communication - Intermittent

17772 - Cylinder 4 Ignition Circuit: Open Circuit

P1364 - 004 - No Signal/Communication - Intermittent

16684 - Random/Multiple Cylinder Misfire Detected

P0300 - 002 - Lower Limit Exceeded

16688 - Cylinder 4 Misfire Detected

P0304 - 001 - Upper Limit Exceeded - Intermittent

16685 - Cylinder 1 Misfire Detected

P0301 - 002 - Lower Limit Exceeded - Intermittent

16687 - Cylinder 3 Misfire Detected

P0303 - 002 - Lower Limit Exceeded

16686 - Cylinder 2 Misfire Detected

P0302 - 002 - Lower Limit Exceeded

17763 - Cylinder 1 Ignition Circuit: Open Circuit

P1355 - 004 - No Signal/Communication - Intermittent

17769 - Cylinder 3 Ignition Circuit: Open Circuit

P1361 - 004 - No Signal/Communication - Intermittent

17766 - Cylinder 2 Ignition Circuit: Open Circuit

P1358 - 004 - No Signal/Communication - Intermittent

************************************************** ************************-





AFTER CLEARING CODES
Sunday, 14 November 2010, 16:52:47
VAG-COM Version: Release 409.1-S

Control Module Part Number: 8E0 909 518 AK
Component and/or Version: 1.8L R4/5VT G 0003
Software Coding: 0016711
Work Shop Code: WSC 12596
2 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 008 - Implausible Signal
16687 - Cylinder 3 Misfire Detected
P0303 - 008 - Implausible Signal
************************************************** ************************-

[sean1.8t]

clear all of those codes. cycle the engine a few times and VAG it again. can't tell what's new and whats old.

sounds like a vacuum leak as Fletcher said.

[diagnosticator]

Since there is a lot of miles on the engine the intake cam drive chain is going to be looser than it should be also. The cam chain does not last forever, and should be replaced.

[seattlematt]

UPDATE

-I swapped the coils around and the misfire always stays on cylinder 3

-reset pulled codes 10+ times now, consistently getting the same codes

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 008 - Implausible Signal
16687 - Cylinder 3 Misfire Detected
P0303 - 008 - Implausible Signal

[seattlematt]

One more note, the car runs great Other than the rough idle. Pulls and boosts normally.

[old guy]

It may be a partially clogged injector. Swap injectors and see if the misfire follows.

[seattlematt]

Well I'm at university Audi today getting my coil pack recall. We'll see if it helps.

[seattlematt]

Just got back from my recall with new coilpacks, still the same problem. Audi was nice enough to clear my codes again for me, but they said it runs fine, didn't notice any problems, LOL. I got back in the car and it's the same thing, rough idle, misfiring. What should I do next?

[cdn20valve]

it's intermitent, or always misfiring and running rough?

[seattlematt]

Always at idle.

[cdn20valve]

I'd do two things if I were you. Swap injectors around, and see if the misfire follows.

And I'd do a comp test on the engine, specifically cyl 3.

Check you cyl #3 spark plug, you may have a loose/damaged/incorrect gapped plug as well.

[widgget]

did you try swapping the EFI like was recommended?
if the issue does not follow the EFI it might be worth giving the EFI connector / harness a good once over to make sure it's connecting properly.

like everyone else mentioned it sounded like a vacuum leak until you mentioned the misfires only on cyl3.

[cdn20valve]

It may still be a vac leak on cyl #3, if the plug is loose. Since he "played" with the plugs, I think checking them is a good idea.

[JMRQuattro]

Not sure about the misfires but I agree with John about the cam chain. I just had mine replaced recently and it was making a rattling sound at the back of the engine, cause it's directly below the raised portion at the back of the valve cover.

[seattlematt]

I went through and retested the compression and got about 148-150 on all cylinders. It's odd considering I keep seeing people getting upwards of 180 on theirs, perhaps it's my tester.

I swapped the spark plugs and found a little more powdery cakey stuff on plug 3. I'll post a pic later.

On another note, looks like University Audi broke one of my coilpack connector tabs this morning, oh well, i guess that's price I pay for getting stuff for free :|

[cdn20valve]

A little low, but still within spec.

"Ash (Lead) Deposits
APPEARANCE: Ash deposits are characterized by light brown or white colored deposits crusted on the side or center electrodes. In some cases it may give the plug a rusty appearance.

CAUSE: Ash deposits are normally derived from oil or fuel additives burned during normal combustion. Normally they are harmless, though excessive amounts can cause misfiring. "

Clean the plug and install it on a different cylinder. see if idle problems go away, or switch to a different cylinder.

[seattlematt]

I swapped the spark plugs and retested. It doesn't seem to be following the plug, but my misfires seem to be a little bit random. I'm starting to get concerned here. The engine make a rattling sound when it misses that sounds very heavy and I don't like it. I need to note that the camshaft chain tensioner is not making the noise that it used to which is still puzzling me, however I'm not sure how it's related. I would assume i would have a code for my CCT if it was failing? It's almost like my CCT is not getting connection.

If you remove the plug from the CCT does the engine continue to idle normally? I can't remember.

[seattlematt]

Ok, so I removed the cam cover and this is what I found.





It looks like my timing marks are off on my chain? If so, my guess is that 1 of 2 things happened.
1. The timing chain slipped a gear while I was rotating the motor by hand (seems highly unlikely)
2. The CCT is malfunctioning and advancing the timing when it shouldn't (this makes some sense since it runs fine at high RPM and the chain is very tight)

[seattlematt]

I counted the rollers and there are 15.8 between the marks.

[DownhillA4]

Hm i've been noticing this weird idle for a few seconds after start-up since I got my waterpump/timeing belt replaced as well not to long ago. I have 54k on the odometer. Strange but i'll check it later this week. Keep the updates coming SeattleMatt.

[JMRQuattro]

From the looks of the second picture, your VVT looks like it's leaking oil.

[wheelmanbg]

This is interesting because I have a similar issue after my timing belt change but mine is 3.0L V6

[seattlematt]

From the looks of the second picture, your VVT looks like it's leaking oil.

There's oil everywhere, how can you tell? I thought the CCT was supposed to use oil to pressurize?

[JMRQuattro]

Because it looks like there is a trail of it coming down from the center where the chain runs over it. Plus if you look directly to the right or left of it, there's not any.

[diagnosticator]

I counted the rollers and there are 15.8 between the marks.

The number of chain links is about right, 16 specified, but the 16th link with the timing marks aligned on the intake cam places the exhaust cam about 1/2 link advanced offset (to the left of,) on the timing marks for the exhaust cam.

[diagnosticator]

A little low, but still within spec.

"Ash (Lead) Deposits
APPEARANCE: Ash deposits are characterized by light brown or white colored deposits crusted on the side or center electrodes. In some cases it may give the plug a rusty appearance.

CAUSE: Ash deposits are normally derived from oil or fuel additives burned during normal combustion. Normally they are harmless, though excessive amounts can cause misfiring. "


Clean the plug and install it on a different cylinder. see if idle problems go away, or switch to a different cylinder.

Note to OP, When cleaning spark plugs, never use a wire brush on the plug tip, it's OK to use a non metalic brush, but a wire brush will leave metal tracks on the insulator tip and short out the plug. Once metal tracks exist on a plug, the marks can't be removed, the plug must be replaced.

[seattlematt]

Ok, problem is gone. What I did
1. installed new spark plugs
2. played with, compressed the cct, sprayed a little WD40 on it (pointless I know)
3. replaced my valve cover gasket

So my best guess is that it was the spark plugs all along.

This is a little odd because I did replace them with another set I had halfway into the problem, just a coincidence both sets were bad enough to cause misfires. None of my plugs have more than 2K on them. Oh well, I'm happy to have my car running again, with a new timing belt :) Going to order a new CCT anyway cuz mine is noisy at 115K.

Thanks to all of you for your input, hopefully I can give some valuable advice in return someday!

[bpodnar]

Well, I was reading all of the posts and recognize my situation. I own A4 B6 1.9 TDI and also noticed strange sound when car is on idle. That sound appeared after I changed all the belts, water pump, coolant and thermostat. I cant describe it correctly but it sounds like rattling but it doesnt appear constantly, would say 80% of time when car is on idle. Can someone tell me is that serious or I shouldnt worry about it?

[cdn20valve]

bponar, you have a diesel. Completely different beast than the OP. If it's an intermitent rattle, I'd check all your heat shields etc.. Or you left something loose. Make sure nothing is loose.

[bpodnar]

Ok, i'd check that, but I think that's not a problem. We'll see. Thanx.

[bpodnar]

Sorry for big delay but I found out what was the cause of rattling sound. It was climate compressor pulley which has falen apart this summer. After i changed it rattle disapeared.

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