Bank 2 all cylinder misfires, cam sensor faults

   #21  

EuroX

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If the engine starts and runs but runs rough. I would suspect you are missing one of the things I metioned, fuel,spark or compression. I would start with spark as connectors at the rear of the cylinder head need to be disconnected or moved out of the way when removing rear timing covers. I would double check the simple basic before diving deep into the timing chain portion. Please check all wiring connections. Ensure connectors are seated and try to reseat them ensure they make a audible click for proper engagement/connection.
 
   #22  

Uwe

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You had / have a thread started for this concern (?) ; for context the forum members should be able to see/read what was already started.
Merged. :)

-Uwe-
 
   #23  

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   #24  

alvocado

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Is there any chance you mixed up (exhaust and Intake) cam adjusters ??
99.9% unlikely. I was very diligent to keep parts ordered and labeled. Cam adjusters were marked individually with a paint marker as well to ensure they went back in the correct locations and avoid any confusion since intake and exhaust are in different positions between the banks.

If the engine starts and runs but runs rough. I would suspect you are missing one of the things I metioned, fuel,spark or compression. I would start with spark as connectors at the rear of the cylinder head need to be disconnected or moved out of the way when removing rear timing covers. I would double check the simple basic before diving deep into the timing chain portion. Please check all wiring connections. Ensure connectors are seated and try to reseat them ensure they make a audible click for proper engagement/connection.
Agree. The harness was laid on the cowl for the job so I've revisited each connector that was disconnected, removed it and reattached. The coil for cylinder 6 connection has a broken tab but that existed before the repair and never caused a misfire. I mentioned the ground wire on the back of the engine which is attached to a bracket that holds two connectors. I've verified the replacement ring terminal on that ground and the wire is secure.

I can move spark plugs and coils between banks but question if a single bad coil would cause an entire bank to misfire. I'll run through the wiring harness one more time tomorrow.
 
   #25  

EuroX

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No one coil will cause the entire bank to mis. May 1 or 2 cylinder on a bank but never 3. I would be checking if spark is present. Also you mentioned that the cams were removed. So that leaves to question. Were the timing tools installed prior to cam removal?? Meaning were cam tools installed to verify engine was on TDC top and bottom?? Or were the cams removed and the block was set to TDC???
 
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stefdds

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I mentioned the ground wire on the back of the engine which is attached to a bracket that holds two connectors. I've verified the replacement ring terminal on that ground and the wire is secure.
You really need to Test the ground ; ie is it a electrically a good ground. Just because it is attached does not make it a good ground. Also, regarding all the plug in connections, I doubt you could have plugged a male plug into the incorrect female receptacle, but...... check to make sure none are interchangeable (switched) with others!
 
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alvocado

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You really need to Test the ground ; ie is it a electrically a good ground. Just because it is attached does not make it a good ground. Also, regarding all the plug in connections, I doubt you could have plugged a male plug into the incorrect female receptacle, but...... check to make sure none are interchangeable (switched) with others!
The ground (circled in red) reads 0.05 ohms so should be good. Is there a way to test the main harness to rule out a bigger signal issue to the entire bank?

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   #28  

stefdds

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Is there a way to test the main harness to rule out a bigger signal issue to the entire bank?
By "main harness", I presume you mean to the coil packs and sensors? It gets a bit tricky without a wiring diagram to id what color wire has each function: ground, power, signal etc. ; you could check for power and grounds to each (I believe there are 4 or 5 wires per plug/coil ! Also, if your not sure regarding a ground, (for testing purposes) you can always use another wire to jump existing grounds to any different ground location ; like another large brown ground wire on the chassis / unibody and not a aluminum casting on the engine.

The tool bar at the top of this page has a "How-To" pull down to source wiring diagrams. As you mentioned, the car ran ok before you started the service, unless you pulled on or crushed/pinched a harness, the function should be ok ; a ground however could get affected rather easily if not careful.

Another thought I had was I would check every plug you disconnected just to be sure that a pin or connector did not get 'folded over" (inside the plug housing) when plugging the connection back together. That would cause significant problems. Please keep us posted how you progress.

Edit: This thought also came to mind: its a bit "out there" but..... is there any chance you exchanged the cams on that bank? That is, exhaust cam in the intake location? Crazy I know as I don't even know if that is possible. Also, if these are short length cam position sensors , remove one or both and look down inside the opening ; is there a ring of some sort present in the center of the opening? Use a mirror if necessary. I'm just trying to think beyond the norm here!
 
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   #29  

alvocado

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I greatly appreciate the professionalism and willingness to help on this forum. It's 1st class. Here's an update on some additional troubleshooting:

1: I disconnected the harness on the bank 2 as done during the repair and inspected all of the connectors and wiring. No sign of bent pins or broken wires.
2. Pulled the cylinder head cover and confirmed that the cams are still in correct timing (see pic).
3. Manually rotated the engine at least one full revolution to confirm no sign of bent valves. Engine rotated fine with no unusual resistance other than that due to leaving the bank 1 spark plugs in generating some compression.
4. Checked all fuses in both internal compartments for continuity - all tested as working.
5. Pulled a cam position sensor as suggested. No sign of a ring other than discoloration below the oring consistent with the rest of the internal area.

The cams are different lengths so it wouldn't have been possible to switch intake and exhaust.

I hate to make a big assumption at this point but it seems like it's a signal issue to the entire bank 2 as the mechanical troubleshooting has checked out so far.

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   #30  

EuroX

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I think checking compression or leak down is the only thing that will rule out bent valves at this stage or check to see if you have spark on that bank.
 
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   #31  

alvocado

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Likely bad news. Compression test revealed the following:

Bank 1:
Cyl 1 - 190psi, Cyl 2 - 185 psi, Cyl 3 - 185 psi

Bank 2:
Cyl 4 - 90 psi, Cyl 5 - 90 psi, Cyl 6 - 120 psi

This is getting beyond my experience with engines so knowing if this 100% confirms bent valves would be helpful. If yes, I'll need to understand what could have caused this to address the root issue while tackling what may involve new bank 2 valves.
 
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   #32  

EuroX

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No I don't think this is a bent valve situation, If you had bent valves you would have zero compression on that whole bank. I think personally Perhaps its slightly out of time. Technically I have seen these engines run with such low compression as 90psi-110psi. However. I think the best next step would be to put a small amount of oil roughly 5ml down each plug orfice and retest the compression. Perhaps the cylinders are just washed out from cranking the engine over and over. This would be my next step if this was my vehicle. If this is the case the compression should come up. However if it does come up then I would be looking at timing perhaps its slightly out of time. IIRC even with all the tools installed there is still some give in the crank rotation even with the pin installed. So to me it sounds like for whatever reason the valve are hanging open slightly, possibly related to timing. Given the fact that your have implausible signal for cam sensors leads me to believe this is the case.

Only other test to be sure you don't have bent valves would be to do a leak down test. Set each cylinder to TDC hold the crank and performed leak down. Anything 5% and below is the norm anything higher and you have either piston ring to wall clearance or carbon in the rings or valve train issues/ timing issues.
 
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   #33  

alvocado

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I pulled valve covers and rotated the engine to TDC. The cam positioning still appears to be very close in sync although I didn't install the cam locks to completely verify (see cam lock bolt holes facing upwards on all four cams below.)

I did have the car running this morning for about 1-2 minutes to check codes and attempt to get a block 093 measurement. I would hop that would have built up oil pressure sufficiently but I'll try adding oil to the cylinders as suggested and retest.

If this is an issue with slightly out of time cams, is the procedure to adjust timing pulling the rear covers, loosen the cam adjusters and rotate the cams back into correct time?

Bank 2:

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Bank 1:

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   #34  

EuroX

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It would be just installing all timing tools, crank pin and cam lock tools, then just loosening adjusters and retorquing everything,if not in time then you may need to roll the cam slighty but you still need to loose the adjuster if rolling the cam I don't remember if both cams have adjusters on them on this engine. I think earlier ones only had them on only one cam. However IIRC those adjuster bolts are TTY. Also not the cams on bank1 don/t look to be perfectly level. Maybe its just the way the angle or orientation of the picture. If they are indeed not flat I would turn the crank slightly till bank 1 is 100% on the money then inspect bank2 and check the orientation to see if its out. However normally What I would suggest would be to try and get the crank lined up and thread the crank pin in some, but not all the way the crank pin should fit into the crank hole and still have some give when its not bottomed out. Then use a ratchet rock turn the crank and see if all cams will lay flat and tool thread in without issues.
 
   #35  

alvocado

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It would be just installing all timing tools, crank pin and cam lock tools, then just loosening adjusters and retorquing everything,if not in time then you may need to roll the cam slighty but you still need to loose the adjuster if rolling the cam I don't remember if both cams have adjusters on them on this engine. I think earlier ones only had them on only one cam. However IIRC those adjuster bolts are TTY. Also not the cams on bank1 don/t look to be perfectly level. Maybe its just the way the angle or orientation of the picture. If they are indeed not flat I would turn the crank slightly till bank 1 is 100% on the money then inspect bank2 and check the orientation to see if its out. However normally What I would suggest would be to try and get the crank lined up and thread the crank pin in some, but not all the way the crank pin should fit into the crank hole and still have some give when its not bottomed out. Then use a ratchet rock turn the crank and see if all cams will lay flat and tool thread in without issues.
That all makes sense. There are adjusters on both sides so each cam can be adjusted and you are correct, the cam adjuster bolts are TTY and would need to be replaced if loosened.

It might be later in the week before I get time to take another crack at it but I'll report back.

I greatly appreciate the advice and extra set of eyes on this.
 
   #36  

EuroX

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Not a problem, I've been around these cars for many years and have seen some very odd things happen. Let me know how you make out and let's get this sorted out so you can enjoy the car.
 
   #37  

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Back at it today. I manually rotated the crank to get all four cams in TDC position and tested installing the cam locks. Everything appears to have remained in sync with both cam locks going on easily and securing the cams with bolt holes facing upwards.

I removed the cam locks and rotated the crank several times looking for any issues with valve springs, rocker arms out of position, etc. and didn't see anything out of the ordinary.

Installed the crank pin with cams facing upwards, rocked the crank to ensure pin engagement and tightened down the pin. Placed cams locks on both banks and they fit perfectly.

I have not pulled the bank 2 cam cover but that may be the next move to inspect the new upper chain tensioner.. It is strange that I have been unable to get a block 093 reading despite multiple attempts.
 
   #38  

EuroX

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Have you tried swapping the solenoid?? or inspected wiring for oil inside the connector possibly??
 
   #39  

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Have you tried swapping the solenoid?? or inspected wiring for oil inside the connector possibly??
I've looked over the wiring multiple times including checking all male and female connections. Connections were covered with painters tape for the repair to keep out debris and are clean.

I do have two new VVT solenoids on hand but will pull the cam cover since everything is open. It's worth an inspection of the tensioner and if that looks good, I'll button everything up and try the new solenoids.
 
   #40  

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Chain tensioner looks good. Chain is fully tensioned, no signs of broken plastic, and the chain appears to be riding on the cam adjuster sprockets. Why Audi switched from hex bolts to torx bolts on these covers is beyond me as they round like butter. Will close it up and swap in two new VVT solenoids. After that, I'm running out of ideas.

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