Camshaft adjuster does nothing at idle and it is not triggering camshaft sensor.

 

Are any codes showing. Misfires?

 

I was under the impression that the camshaft advance actuators only energize at a certain RPM so that your cams will then advance. It is an on or off system.

At least I thought that was correct....

 

Chris,

I think you are right-on. They advance to give you that extra boost of power/power curve is extended..
Now look at the animation on this video at 2:42?

Enjoy,

Martin

 

Thanks Martin...I thought I had that nailed correctly.

Cool video...Definitely 'explains' the adjuster for sure! Wish I could speak/understand German though. You find all the cool stuff...

Chris

 

Okay, folks, let's put some thinking on this. What could happen if it went haywire? None of us engineered the M120....and neither did any of us work in MB warranty parts when these were around (I'm fairly sure). so we don't really know.

Diagnosing problems like this are not easy. NO check engine light. Not easily repeatable.

What do we know? It's a spark issue. Unburnt fuel. Happens below a certain rpm, and causes occasional huge miss at full load in high rpm as well (recent).

Bad cam sensors usually throw a code. Never, from my own cars to dealership work, have I seen an example that did not - obd1 and obd2. So what else can knock out spark for an entire bank in such a fashion? Now let's see that there's a part, almost entirely mechanical (so harder to throw a CEL), that when unplugged caused the symptoms to not change. It affects the cam sensor. Following the general rules of diag, for a problem with no Internet backlog to look upon, it seems to me this might be the answer.

So for all of you naysayers: If anyone else has a better idea, speak up. I asked in several threads about this issue previously and everyone was scratching their heads. I'm about solutions, not shooting them down.

Clark.



footnote: No, it has probably has affect at idle, and the symptom is not present at idle - only rarely and when the foot's down past ~10%.

 

Now let's see that there's a part, almost entirely mechanical (so harder to throw a CEL), that when unplugged caused the symptoms to not change.

Ok, so you have driven it, with the cam adjuster magnet unplugged?
And the performance of the car (in low RPM and high RPM) did not deteriorate, while
the "Happens below a certain rpm, and causes occasional huge miss at full load in high rpm as well (recent)." still happens?

Yes, then I would think that the magnet is faulty, or that the actuator is stuck in
either positions.

When unplugging, you should also get the open circuit error code for the solenoid;
STAR TekInfo (code 18 or 50)

I would read more about it here, though;
http://www.mbwholesaleparts.com/downloads/StartunedArchive/2011/MBST-VariationTheme.pdf

OT; Yes, I found out today, that StarTuned still has some good articles in the archive linked from this page!
Technical Information | Mercedes-Benz Wholesale Parts
some still very relevant to our 140.

br,
syljua

 

OKAY.....

I replaced the cam magnet last night (indeed used the $35 MBZ unobtainium silicon), and have driven around a good bit today. Early on the high RPM stutter was still there, but that went away fairly quickly. The below-3.5k-rpm-half-power-nonsense has not triggered again, but I cannot confidently say it is gone without a few more weeks.

On the other hand, I got a CEL, giving me blink codes 6 - idle speed control faulty (which is odd, because my idle was ~50rpm jumpy before this and smooth now) - and 35 - lambda fault air meter/fuel/or ignition bank 2. Not sure which side is bank 2, but I replaced the driver's side magnet. Cleared the codes, hopefully they don't return.

Fingers crossed.

Clark

In unrelated news, I discovered that W210 steering angle sensors carry the same part number, and unlike W140s those cars are in abundance in local junkyards, so the driving I did today was going around to all of those. You may have inferred already that I went around to all of those only to find that none of them actually had a steering angle sensor. Must only be included in some rare option.

 

The below-3.5k-rpm-half-power-nonsense has not triggered again, but I cannot confidently say it is gone without a few more weeks.

Good

I re-sealed my magnets myself on friday and made some related videos.
(sadly I already see some oil drops, but I think thats then from the connector)

Moving of the advancer end (not very interesting, but should be checked
when the magnet is off the engine);

http://www.pvv.org/~syljua/merc/M119CamshaftAdvancerEnd.mov

And this, which with a DAS system, you could check the running characteristics
when the magnet is enabled on idle (will worsen the idle quality). I did activate
it twice during the video;

http://www.pvv.org/~syljua/merc/M119CamshaftActuator.mov

br,
syljua

 

This particular problem has not returned (and the high-rpm hesitation was actually a bad MAF (a bad Bosch-reman. MAF at that) I replaced yesterday). Considering the regularity of it previously, and having driven about a thousand miles since replacement, I think we can chalk this one up as a victory. Who knows what the heck was going on with the old magnet, but it's not my problem anymore!

 

Just want to post one final update - the problem has not returned once, and I have driven it every day. This has been solved totally by the camshaft magnet.

 

Bravo Clark. Perseverance always pays off.