14 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHP0012 after replacing timing chain tensioners
Leading reported evidence
Replace wiring
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
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0
Unsuccessful attempts
1
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Read evidence and context
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Performed · outcome unconfirmed
I think you have found one problem, the swapped wiring.
Leading evidence: 'Replace wiring' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'cause of the cam deviation' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Adjust exhaust cam alone is not going' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
Swapped wiring does not cause the cam shaft to misalign.
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Suggestion
I think you have too much chain slack between the IMS sprocket and the Intake Sprocket, so adjusting the exhaust cam alone is not going to solve it.
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Suspected cause · Original poster
These bundles include the variocam actuator connectors, which is very likely the cause of the cam deviation.
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Suggestion · Original poster
While doing everything I took the opportunity to replace all 3 cam chain tensioners and the IMS seal.
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14 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Outcome without a verified action link
Swapped the wiring harness between cyl 2 and 3 and everything is back to normal.
Just finished doing some service on my 02 C4S after an AOS failure.
While doing everything I took the opportunity to replace all 3 cam chain tensioners and the IMS seal. While doing this I ensured that the crank was locked at TDC and the locked the cams with a home-made tool. Upon reassembling and starting the car up I'm getting a P0012 code - "A" Camshaft Position - Timing Over-Retarded (Bank 1)".
When checking cam deviation in durametric, sure enough the Bank 1 cam is showing 19 degrees of deviation.
Now the question is, did I somehow manage to jump a tooth on the bank 1 chain? And if so, what are the steps needed to re-time the motor? I'm mentally preparing myself for removing everything and starting from scratch, but is that necessary? This is a 3 chain motor which doesnt seem to have a lot of documentation online.
Found this post after some searching, seems like an almost identical issue. Is there any reason I couldn't re-set the timing the same way they did it in post #22?
http://986forum.com/forums/performan...acement-2.html
Pulled the cam caps off and turned the crank to TDC to visually inspect how far off they are. To me it doesnt look like either of the cams have jumped a tooth. I put my cam locking tool in to see if I could get it in, and it will go into the intake cam perfectly aligned. When installing into the exhaust you can see that its slightly off. Seeing as the ECU only measures intake cam timing, and it appears to be perfectly set, what gives? I'm also getting misfire codes on cylinders 2 and 3, but not 1.
Will do. I assume I can just do this but loosening the 4 bolts on the exhaust cam, manually turn the cam by the notch and re-tighten, correct?
This still doesn't explain why durametric is reporting so much cam deviation though...
I think you have too much chain slack between the IMS sprocket and the Intake Sprocket, so adjusting the exhaust cam alone is not going to solve it. I don't know if that would fix your issue, but it is worth a try. And if that does not fix it, then you need more than your home-made tool. You need the tool to hold and tighten the intake sprocket AFTER tensioning the chain correctly. That might not be possible with engine in.
Perfect, thanks. Not exactly something I want to be doing if I can avoid it.
Few new pieces of information to add, as well as things I forgot to include when originally posting:
I installed a new crank position sensor when doing the service (old one was fine but I figured I might as well with the engine out)
Pulled all the plugs to do a compression test
All cylinders are reading at 210psi - great news
All spark plugs were brand new when installed and it is clear that cyl 2 and 3 have NEVER fired. So this isnt an intermittent misfire.
There is evidence that there has been spark, but no ignition of fuel.
When originally locking the cams to do the service, I really struggled to get both the cam tool and crank at TDC at the same time
I cheated this by locking the cams when they were aligned and then turning the crank a couple degrees to get the pin in (yes, I now realize this was stupid)
I'm beginning to think the cams have been off this whole time - and while this is a problem, is not the main issue at hand
Follow up questions:
I had the fuel rail off during service, is there enough slack in the wiring harness that I put the injector or coilpack connectors to the wrong cylinders?
Is there any way to test this via Durametric?
Or should I just try to swap either of these and see if it fixes the misfire?
Could the new CPS be the cause of the misfires and DME thinking there is a cam deviation?
If this was the case, would it not present itself on both banks?
Why is cylinder 1 firing?
Could a faulty cam position sensor cause the error?
Why would it have failed during service?
Worth swapping between banks to see if the error follows the sensor?
I had the valve covers off, is there any possible way I moved the trigger wheel for the cam sensor?
That's enough thinking for one night... Thanks for everyones help
Cyl 2 and 3
Cyl 1-6 from left to right
Couldn't sleep and had to run to the garage to look at the wiring harness and compare against a photo I took before tearing everything apart. I think I've solved this! Somehow I manged to swap the wire bundles for cyl 2 an 3. These bundles include the variocam actuator connectors, which is very likely the cause of the cam deviation. I'll get a better look tomorrow and report back, but I think this is the problem.
I think you have found one problem, the swapped wiring. But, you still have an exhaust cam out of time. Swapped wiring does not cause the cam shaft to misalign.
Absolutely agree. One problem at a time
Is it wrong to think that if the variocam actuator connectors were swapped this could lead to cam deviation? I'm still struggling to see how the exhaust cam being out of time could cause the DME to see cam deviation since cam position is measured by the intake cam.
Swapped the wiring harness between cyl 2 and 3 and everything is back to normal. Cam deviation within spec, no misfires.
I�ll look at the exhaust cam timing when I have a chance but this job has me spent.
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