GetAUDImyCar

So I've got a 2004 Audi A8 4.2
I'm a pretty handy guy and decided to tackle the timing belt job and all the stuff that goes with it including pulleys, water pump and gasket, thermostat, valve cover gaskets along with the chain tensioner gaskets. Anyway you get the point. So I finished the job and started up the car to fill with coolant and what not. Pull it out my shop and continue coolant procedure. In the beginning the car was idling at higher RPMs and I did not hear any problems. Then my car idled down a bit and then I could hear light misfire on bank 2 and car would shake and shudder a bit.

I hooked up to VCDS and got the following:

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Address 01: Engine Labels: 077-910-560-BFM.clb
Part No SW: 4E0 910 560 A HW: 4E0 907 560
Component: 4.2L V8/5V G 0070
Revision: 00000000 Serial number: AUX3Z0D0532548
Coding: 0007773
Shop #: WSC 02313 785 00200
VCID: 1F4D8EAFCE0837BE93-804A

11 Faults Found:
16434 - Oxygen (Lambda) Sensor B2 S1: Heating Circuit
P0050 - 004 - Malfunction / Open Circuit - MIL ON
18282 - Valve for Torque Support Mount
P1874 - 001 - Short to Plus
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - - Intermittent
16689 - Cylinder 5
P0305 - 001 - Misfire Detected - Intermittent
16692 - Cylinder 8
P0308 - 001 - Misfire Detected - Intermittent
16690 - Cylinder 6
P0306 - 001 - Misfire Detected - Intermittent
16691 - Cylinder 7
P0307 - 008 - Misfire Detected - Intermittent
17745 - Camshaft Position Sensor (G40)
P1337 - 002 - Short to Ground - MIL ON
17800 - Camshaft Position Sensor Bank 2 (G163)
P1392 - 001 - Open Short to Plus - Intermittent
18041 - Accelerator Position Sensor 2 (G185)
P1633 - 002 - Signal too Low - Intermittent
16486 - Mass Air Flow Sensor (G70)
P0102 - 002 - Signal too Low - Intermittent
Readiness: 0000 1001

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Address 02: Auto Trans Labels: 09E-927-156.lbl
Part No SW: 4E0 910 156 E HW: 09E 927 156 A
Component: AG6 09E 4,2L5V USA 0110
Revision: 00000001 Serial number: 0020078
Coding: 0000002
Shop #: WSC 02313 785 00200
VCID: 24478143E76E1466CE-8070

2 Faults Found:
18269 - Throttle Position Sensor (G79)
P1861 - 000 - Error Message from ECU - Intermittent
Freeze Frame:
RPM: 128 /min
RPM: 128 /min
RPM: 0 /min
(no units): 30.0
(no units): 25.0
Temperature: 25.0°C
T.B. Angle: 60.0°
Voltage: 9.36 V

18265 - Load Signal
P1857 - 000 - Error Message from ECU - Intermittent
Freeze Frame:
RPM: 128 /min
RPM: 128 /min
RPM: 0 /min
(no units): 30.0
(no units): 25.0
Temperature: 25.0°C
T.B. Angle: 60.0°
Voltage: 9.36 V


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I have changed out the oxygen sensor on B2 since this scan. I have also taken the coil pack from the other bank and tried it out. Same thing. Swapped the spark plugs as well, no difference bank 2 keeps misfiring. Majority on 5 and 6 with 6 taking the lead in a misfire count at about 47 in a couple minutes.

I then decided to take the valve cover off on Bank 2 to see if maybe the timing was off on the cams. Got the cam lock bar and installed it. The cam notches are perfectly in line with the little arrows.

I also noticed that I guess I had broken a vacuum hose that connects two vacuum one way check valves that are located behind the valve covers. Would that vacuum loss be enough to cause all of bank 2 to misfire?

I'm going to order two new cam position sensors to hopefully clear those codes as well. I guess I'm just looking for someone to tell me that all of these things combined are the problem. Could it be the crank timing off a bit causing misfire on that whole side?

GetAUDImyCar

I took some pics of the driver's side cam chain. I count about 15 rollers which is the problem in my opinion. Does anyone know what the count for that side is. I'm getting conflicting information. I heard 15.5 and 16 also I included pics of the time alignment indents and a Cam chain view from cabin towards front of vehicle
This is the lower cam on driver sider
Upper cam alignment mark on driver side
rrows

GetAUDImyCar

So after reading up on some other cam alignment issues. I've come to the conclusion that my cams are in fact properly timed. I can't seem to find any information that leads me to think otherwise. Which leads me to my next question. Should I just try to re-align the crank shaft? Or do you think it more or less has to do with the vacuum issues and the now new MAF sensor (see vag diagnostic info above). I've now fixed all the vacuum lines which shouldn't be an issue anymore. I'm hoping someone can help soon because I'm not sure whether to close the valve cover or not in case my cam teeth are not aligned.

target39

If you truly are at 15 teeth between slots, then your camshafts are aligned at the driver side. I just did this same job last month (changing tensioner pads) and wondered why I was getting misfires on Bank 1 (US passenger side) despite triple checking perfect alignment AFTER the pad change. I thought it was spark plugs/coils but switching them around didn't work. Ultimately, I got a borescope and inspected the piston tops and sure enough, there were valve imprints and the intake valves were bent.

Before changing out the broken tensioner pads, I took pictures of how the alignment was BEFORE pad change and while the driver side was at 15 rollers, the passenger was around 18 or 19 meaning the intake camshaft was over advanced and forced the intake valves down before the pistons could retreat far enough into the cylinder, making contact. It only takes a couple of revolutions of bad timing to make the valves meet the pistons, so somewhere along the line of cranking the engine before the repair, the engine must have jumped timing badly enough to bend the valves.

If I were you, my next step would be to order a borescope off Amazon for $20 and inspect the piston tops as well as the valve stems as much as you can, which is what I did. It's fairly easy to tell when you have bent valves with a borescope if you can see obvious impact marks (not to be confused with original valve relief cuts).

I'm hoping that's not your case as it's a big, expensive job to pull the head and replace it. I'm still trying to figure out a strategy on how to do it without moving the engine/subframe but it seems possible (I've seen pictures online of someone with a BFM engine replacing cylinder heads with the engine still in the car) as long as I can access the rear cylinder head bolts and exhaust pipe nuts.

Let us know if you do have valve damage and plan to replace the cylinder head. Perhaps we could bounce some ideas off each other in trying to do it in as little time/work as possible.

GetAUDImyCar

I'm almost certain there is no damage to the pistons and valves. I don't hear any kind of knocking or obvious noise when I turn the crank and everything lines up with cam lock bar. I ordered two new cam position sensors and new bosch spark plugs and I'm going to reinstall the valve cover and gasket. I'm still in the process of doing the oil coolant pipe as well cuz I have a coolant leak from the plastic union pipe being broken. I ordered a billet aluminum one to replace it and the needed gaskets. When I'm done with that I should get my new cam position sensors and install as well as the new spark plugs. Since all the vacuum hoses have been replaced I will then start it up again and hook it up to vcds and check it out.

GetAUDImyCar

I'll give updates in the next couple of weeks as I get time to work on the car.

GetAUDImyCar

Got all my parts in and got some time. Ended up tearing both valve covers off to check can chain links and they were both on the money. Covered them back up and took the whole front end off and just re-did the timing altogether. Turns out it was just a hair off when I put the cam alignment bar on. So I popped the cam sprockets on the driver and passenger side. Popped crank lock pin tool in and just really checked and double checked everything and torqued to spec. I put new spark plugs in and camshaft position sensors. Put it all back together and cleared codes in vcds. Car started but obvious mis-fire, checked with vices and it was only cylinder #7 now. Messed around with it driving it and with vcds.

I gave up that night and went to bed. Next day started the car and whaddya know. No mis-fire and cars idles smooth but check engine light is still on. Says it's cam position sensor now only. Turned out one of the new ones I bought was defective so I put one of my old ones in. Check it in VCDS and clear codes. So far so good. Car has no check MIL light on and drives like it's brand new with 175k.

I did a LOT to this car recently in terms of maintenance and I've really come to enjoy the Audi engineering. I did all the timing maintenance including cps, seals and gaskets, water pump and thermostat, pulleys and tensioners, pulled plastic coolant pipe and replaced with new billet aluminum one from gruven parts and changed out all the o-ring seals on coolant pipes and oil cooler. New spark plugs, was going to get new coil packs but ended up not needing to. Got all new upper control arms from AM auto parts which I found online for like 85 bucks which I'm going to give a shot. So far they are smooth. I'm keeping the old control arms and I'm going to press new bushings in for the future. Installed new lemforder sway bar links from fcp euro for a total of like 40 bucks on sale. All in all its been a crazy learning process but thanks to the guys on here it's made learning about this car fun! Thanks for all the help.

richard-tx

What likely happened was that a lifter got too far to the end of it's travel and would not let the valve seat until the oil pressure leaked down. Now take the time a make sure that you adjusted the belt tensioner correctly. Take your time and read that part CAREFULLY! I know more than one fellow that destroyed an engine because the tensioner was set too tight.

GetAUDImyCar

I did the tensioner exactly as the the tutorial showed me and the car is running great now. This is the first Audi I've ever owned, driven, worked on and its been a pretty steep learning curve but I'm getting there. Oh yeah I forgot to mention that I went ahead and changed out all the vacuum lines under the hood as well.