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Fuel pressure is solid at ~55PSI. Also as has been mentioned, I would guess a fuel pressure issue would affect all cylinders equally and not just show up only at 1500RPM. Something funny is going on only on bank 1, and i need to figure out what it is lol.
Going to swap/clean cam solenoids as I think they are interchangeable from side to side. car isn't throwing any cam or timing codes but im not sure what else it could be at this point.
Ah, okay. So the issue is not appearing under any load...just at 1,500 RPM. Odd...
I've encountered lazy cam / crank position sensors on other platforms before, but they would either cause a no-start or the car to feel down on power without codes.
If these sensors completely failed, however, they should throw a code.
Solenoids are indeed the same. Reasonable next step.
This user with a W220 was also stumped by a very unusual problem - TL;DR you could try temporarily disabling/turning off solenoids, one by one, to better pinpoint the problem. Check out his thread, he's thrown a LOT of parts into his car, went through different shops, until he finally found the problem!
But for this, you'll need the Xentry/DAS to access the cars' ECU directly. Hope this helps!
Fantastic video as always Chris, keep it up and best of luck!
Sorry to see all the work you've done so far to try and resolve the issue. At the very least, most of what you did was good preventative maintenance anyway.
I just wanted to mention that in addition to the cam solenoids, I'd consider swapping over the cam sensors themselves as well, assuming both banks are interchangeable which they appear to be. Here's an FCPEuro link to one of the sensors, but there is a cool 3D cam timing diagram below it. Basically, I'm referring to items 10, 11 and 13
Hope you get this resolved and we get to see the update video!
If I may, I'd like to point you to this thread as well - TL;DR after much troubleshooting, a clogged fuel rail was the culprit! explanation taken from another forum:
Low fuel rail pressure is the cause of your decreased power- a computer induced limp mode. When the fuel rail is starved for fuel by a restricted filter the code is thrown. Restarting the motor will get you back to full power until it happens again, but the code is still stored.
Since you got brand new injectors, and you swapped out coils to ensure that they're okay, it'd be the next thing to inspect, followed by the fuel filter (another prime suspect) and pump, IMHO. You got no fuel rail-related error codes, but I guess you could try that out, while you get your hands on a Xentry/DAS and see what happens!
Give it a shot, can't hurt to try!
Last edited by WeisseTiger; 02-27-2024 at 03:36 AM.
Had some more time to mess with the car last night and i've made some progress:
Decided to inspect the passengers side bank cam position and solenoid wiring. Everything looked fine. Cleaned/inspected cam position sensors and solenoids. No change. Said "screw it" and decided to unplug the passengers side exhaust cam solenoid. Fired the car up, held revs at 1500RPM and FINALLY zero misfires. Took the car down the road for the first time in a month and it ran perfectly. No misfires on any cylinders. Took it back home, plugged the sensor back in, fire up the car, boom it misfires and shuts down between 1500RPM again. So I think i've narrowed my issue down to the VVT system. Now, is it a sensor, solenoid, or possibly an adjuster itself? I'd like to think its not an adjuster since they make zero noise and I just rebuilt them 10k miles ago. I swapped exhaust cam position sensors from bank to bank, since those are interchangeable, no change.
Here's where it gets a little interesting: I also swapped the exhaust solenoids from bank to bank, expecting the misfires to go over to that bank, but it still misfires on the same cylinders (1, 3, 4 and also cylinder 6 a bit as well). This leads me to believe at least the exhaust solenoids are good since behavior is unchanged on both sides. I haven't tried swapping the intake solenoids yet.
At this point i'm thinking its one of a few possibilities:
Crank position sensor. Perhaps this sensor isn't reading correctly at certain RPM and therefore can't correctly trigger the VVT. Would explain why the car runs perfect with the VVT system disabled.
Intake Cam position sensor. Perhaps this sensor isn't reading correctly at certain RPM and therefore can't correctly adjust cam timing. Would explain why the car runs perfect with the VVT system disabled.
Intake cam solenoid. I might try swapping these later
Bad adjuster. Unlikely, but i suppose its possible? Doesn't make any noise.
Open to suggestions/thoughts. I see the light at the end of the tunnel but i'm not quite there yet!
I'd probably start with swapping the intake cam sensor and solenoid to the other bank and see if anything changes. It will at least help rule them out.
If nothing changes then I suppose you can try a crank sensor. It's cheap enough as $20-30 bucks.
Had some more time to mess with the car last night and i've made some progress:
Decided to inspect the passengers side bank cam position and solenoid wiring. Everything looked fine. Cleaned/inspected cam position sensors and solenoids. No change. Said "screw it" and decided to unplug the passengers side exhaust cam solenoid. Fired the car up, held revs at 1500RPM and FINALLY zero misfires. Took the car down the road for the first time in a month and it ran perfectly. No misfires on any cylinders. Took it back home, plugged the sensor back in, fire up the car, boom it misfires and shuts down between 1500RPM again. So I think i've narrowed my issue down to the VVT system. Now, is it a sensor, solenoid, or possibly an adjuster itself? I'd like to think its not an adjuster since they make zero noise and I just rebuilt them 10k miles ago. I swapped exhaust cam position sensors from bank to bank, since those are interchangeable, no change.
Here's where it gets a little interesting: I also swapped the exhaust solenoids from bank to bank, expecting the misfires to go over to that bank, but it still misfires on the same cylinders (1, 3, 4 and also cylinder 6 a bit as well). This leads me to believe at least the exhaust solenoids are good since behavior is unchanged on both sides. I haven't tried swapping the intake solenoids yet.
At this point i'm thinking its one of a few possibilities:
Crank position sensor. Perhaps this sensor isn't reading correctly at certain RPM and therefore can't correctly trigger the VVT. Would explain why the car runs perfect with the VVT system disabled.
Intake Cam position sensor. Perhaps this sensor isn't reading correctly at certain RPM and therefore can't correctly adjust cam timing. Would explain why the car runs perfect with the VVT system disabled.
Intake cam solenoid. I might try swapping these later
Bad adjuster. Unlikely, but i suppose its possible? Doesn't make any noise.
Open to suggestions/thoughts. I see the light at the end of the tunnel but i'm not quite there yet!
I have seen cam solenoids sticking over time and have required cleaning out. If you swap out the solenoid, make sure to inspect/test the passenger side solenoid (voltage, resistance, clean). The solenoids are not cheap, so I'd ensure functionality first. Same thing for the cam sensors, test both harness and sensor for voltage.
If swapping out to other bank, consider doing either the solenoid first or the sensor, but not both.
Been doing some work with HP tuners. Seems it may be more of a generic misfire than I thought. Consistently seeing misfires in #6 as well.
Also to note:
Cams and solenoids appear to be working at least to my untrained eye. Cam angles for all 4 move around and stay near the commanded angle, which would lead me to believe that possibly the cam sensors and solenoids are working properly.
Short term fuel trims are significantly lower (negative) on bank 2. I believe this indicates a rich condition.
Anyone know if unplugging the cam solenoids trips the car into open loop? That might help me narrow this down to a fueling issue if we can determine the car runs perfect in open loop vs. closed loop.
About to fire up the parts cannon and start throwing ***** at this thing lol shes getting on my nerves
Hang on a minute though. I'll bet the guys here will have something to say about this. Could be helpful. Just a guess, fuel pressure maybe? Fuel pump going?
Watched your posted video and a couple others on the channel. Enjoyable content, subscribed.
Originally Posted by MTBSully
Been doing some work with HP tuners. Seems it may be more of a generic misfire than I thought. Consistently seeing misfires in #6 as well.
Also to note:
Cams and solenoids appear to be working at least to my untrained eye. Cam angles for all 4 move around and stay near the commanded angle, which would lead me to believe that possibly the cam sensors and solenoids are working properly.
Short term fuel trims are significantly lower (negative) on bank 2. I believe this indicates a rich condition.
I loaded a recent data log into VCM Scanner and observed something very similar (+27-28 deg. intake and -14-15 deg. exhaust) when stationary, but at idle.
Not sure if this is helpful, but over the course of mixed, mild, driving I'm recording a range of -2 to +28 deg. intake and -16 to +18 deg. exhaust.
As for the fuel trims, hard to tell from just a screenshot. A STFT variation of 5% doesn't seem that significant, and if that was logged right after a CEL was cleared (resetting adaptations) then it may not be giving an accurate picture.
Anyone more experienced with data logs, please keep me honest, but I don't think there's a smoking gun here unfortunately.
Might be worth it to take up @skratch77 on his kind offer to borrow his Xentry setup and scan deeper.
Think it would be worth flashing the stock ECU tune on and see if it still does it? Then flash the aftermarket tune back on and try again? Not on Mercedes, but i've had other cars' ECU go Simple Jack on me before and give strange issues. Something free to try anyway.
Think it would be worth flashing the stock ECU tune on and see if it still does it? Then flash the aftermarket tune back on and try again? Not on Mercedes, but i've had other cars' ECU go Simple Jack on me before and give strange issues. Something free to try anyway.
man i keep coming back hoping you'll have found the solution. any luck?
Not yet, been on the road for vacation/work for the past 2 weeks and haven't had time to touch it. This weekend i'm going to replace the crank sensor since its cheap, re-flash the stock tune to see if anything changes and maybe some other little things.
Could be fuel related still. The fuel draw on idle is decreased and somehow causing issues for emissions. The only reason for VVT during idle and coasting is always emissions.
During idle, VVT and fueling is commanded to decrease usage and maintain emissions mapping as long as the solenoid is in place.
When the solenoid system is removed fueling and timing defaults to non-emission maps??
Replaced crank sensor. No change. Running out of ideas over here lol.
Still can't understand why it runs perfect with cam solenoid unplugged.
Hi, Mercedes dealer tech here .
At first, sorry for my bad english ahah
I had a customer c63 with the same kind of problem of you in the past. I dont remember exactly the fault codes but it was misfire on bank 2 Car runs great before reaching operational temperature . I found Z splice ( connection where multi wires come and split power ) behind left side of cylinder head near exhaust manifold.
It was oem splice. At hot , the welding inside the splice melt and cause bad connection . It was the alimentation of mulitple ignition coils.on bank 2
I remember only have code for misfire , no fault for open circuit for ignition coils activation .
See the picture, its was under the clear shrink tube . I just reweld the wire and problem was solve. Z-Splice Behing cylinder head bank 2
I finally caved and brought the car to Mercedes down the street from my house. I've been travelling like crazy lately and got other cars to work on so I'd rather just pay someone to diagnose at this point. Its been there for a couple of weeks.
At first they called and told me it was the bank 1 exhaust cam solenoid. So they replaced that, which didn't fix it, so now they are saying it is the bank 1 exhaust cam adjuster.
I rebuilt all 4 adjusters 10,000 miles ago with the 63 motorsports plates. I suppose its possible one of them went bad somehow. None of them make any noise.
Has anyone heard of or experienced a cam adjuster that doesn't make any noise but that causes misfires? perhaps sticking or not moving properly which causes misfires?
I was hoping the dealership would have a concrete "yes this is the problem" but it was more of a "this is the only thing left that it could be"
Bummer. Was hoping to see a resolution on this one, as i'm sure you are too. Funny how you take it to the "pros" because you want a proper diagnosis and not just throw parts at it, yet throw parts at it is what they do. On the cam adjuster, only thing i can think of is if you over torqued or under torqued the bolts on the faceplate could possibly lead to adjuster malfunction.
02-21-2024, 02:21 PM
