AudiForums.com - cam tensioner

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- - cam tensioner - code 17930 (https://www.audiforums.com/forum/audi-a8-10/cam-tensioner-code-17930-a-160677/)

cam tensioner - code 17930

I did some more troubleshooting on this last night. My wife's car which has been getting a recurring CEL the last couple of months. No noise or driveability problems.

With this code, ELSA and Bentley have you run through some output tests to narrow down the problem. Initially, the solenoid tested bad so I replaced it with a new one - no change. I verified that the new one is within spec last night and tested the old one just to be sure.

I then rigged up a 12v LED and some resistors (creating the "VAG 1527 diode test lamp") so I could run the output tests with the light plugged into the connector. It passed those.... the light comes on once when the car is started and will flash when running the output tests.

If I'm reading the ELSA and Bentley correctly, the tests have effectively ruled out an electrical issue. The next step is to replace the ECM and the last step is to replace the cam tensioner itself.

I have a new tensioner but don't want to go through the trouble of changing it only to find out that wasn't the issue. If I clear the code it will come back on within about 5 miles.

Any thoughts on what to do next? I am going to pull the ECM connector and re-seat it tonight.

thanks,
Bob

P.S. - car is a 2000 A8, 4.2 with 190k miles

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17930 - Camshaft Adjustment; Bank 2: Malfunction
P1522 - 35-10 - - - Intermittent

I know that Bentley says that if wires show no problem, then replace ECM...if that doesn't work, THEN change the mech adjuster. Wow, what a way to test it!
If you could get access to a VAG test Box (or equivalent?) you could check control wire signal (like in Bentley), you might eliminate the ECM without having to replace it.
I believe the tests you've run eliminated everything but that. I assume the flashing light test was from cam position sensor?

Honestly those cam sensors never go bad, those hall effect sensors are too simple to fail. 90% of the time a cam adjustment fault comes up it has a loose or blown out timing belt tensioner. The other 10% is the ECM. I've NEVER replaced a cam sensor and fixed that fault code.

I would pop the upper timing belt covers off and grab the belt where its easiest to twist, then try and twist it. If you can twist it 90* or more, one or more of the tensioners is shot.

I just looked up the code, sorry i didn't pay attention. The code more or less means the tensioner solinoid isn't working correctly, i would say since you have the tensioner in hand i would replace that first. Those usually only last 100k-150k as it is.

Just to clarify, when you say "tensioner solenoid isn't working properly" do you think it's not working because of a mechanical issue with the tensioner?

I replaced the solenoid already. The old one was dead, I replaced it with a brand new one (which is why I have a new tensioner) and it's within spec at 16 ohms. No change after doing this.

Is the solenoid trying to work but it just can't operate because the tensioner is jammed? That would make sense but the "intermittent" part of the code bugs me.

SilverD2, I'm going to assume it's not the ECM since I don't really have a way to test it. It's stayed dry and I don't have any other driveability issues. I'm getting power to the connector which the blinking LED showed.

thanks guys

Bob

Just a guess about the "intermittent" thing: The solenoid actuates to push the valve to the advance setting, which would engage at higher rpms..at idle and low rpms the solenoid is in the same position as engine off. OR the valve or adjuster piston (all part of the mech unit) could be sticking only part of the time.

I think you are probably correct...I think the code is being tripped because the solenoid is receiving the signal, but the cam pos sensor sees no change in timing. I'm sorta surprised that you're not getting any cam timing codes, too (16404 thru 16407). Just a guess, but apparently they're being overridden by the first code, narrowing down where the last correct signal was received...because if the system simply detected improper cam timing at a given rpm, it's supposed to give an over-retarded, over-advanced or similar specific code.

One more question: Did you hook a test light to the control side of the solenoid plug? (or just the cam pos sensor?) ...if so, checking the response for the same test on the other bank's solenoid (and getting the same) might give me more confidence before starting the job.

The way I read the rest of the trouble-shooting guide in Bentley and your results, it DOES seem to be the mechanical adjuster.

Would love to see pics of what you find, if you can...worn/broken chain slide pad, stuck pressure valve or stuck adjuster piston(?)

What do you mean you changed the solinoid? They don't sell the solinoid seperate, it only comes with a new tensioner.....Unless you pulled it and took it the dealer and got it straight from germany, or worse yet.....the junk yard..

Those adjusters just wear out, the chain is riding on a piece of plastic, steel on plastic isn't a good combo for longevity, thats why they only last 150k.
http://www.ecstuning.com/Audi-D2_A8-...oner/ES261322/ Just look at the yellow pieces on this tensioner, thats what the chain rides on.

I bought a new tensioner and swapped just the solenoid over to the old tensioner since it failed the impedance test in the Bentley.

Everything is new but I figured I would start there first.... it was about a 10 min swap.

I'm just going to change the tensioner this weekend (and reinstall the new solenoid). I'll let you guys know if it works.

Bob