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2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Also, how are misfires detected? I understand that knock sensors, fuel trim, and timing. An anomaly is detected by the knock sensor when a particular cylinder is supposed to be firing. Raw fuel, detected by the A/F (O2) sensor confirms the misfire at that moment. I could be wrong. We should check his "smooth running" state.
@S-Prihadi what about my numbers? This is on the M276.8 engine. They look very much like the OP's numbers. I will try today with XENTRY and maybe Autel, to confirm the readings. I will also check my M276.9 engine. If my numbers look similar to these, I'm going to determine valve timing is not the problem.
Let's look at the basics and retrace our steps. Gasoline combustion requires the right amounts of air, fuel, compression, spark, and timing. (Timing affects compression and spark.)
Also, how are misfires detected? I understand that knock sensors, fuel trim, and timing. An anomaly is detected by the knock sensor when a particular cylinder is supposed to be firing. Raw fuel, detected by the A/F (O2) sensor confirms the misfire at that moment. I could be wrong. We should check his "smooth running" state.
Does Autel have smooth running test for MB ?
Over 3 meter per second is deemed as misfire.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
Ah, yes, I forgot about change in crankshaft speed during a misfire. That actually is more reliable than using knock sensors since there could be other vibrations happening. Smooth running is pretty amazing. I wonder if this is a Mercedes thing or do other manufacturers so something similar?
So, your camshaft timing numbers are similar to mine and the OP's. (My numbers have the intake cams on top.)
I do have a long crank.. how can I tell if this has shifted? Does the vvt cover have to be removed?
Long crank and disabled Eco Start/stop are both the result of that timing value out of range. After I replaced my VVT and tensioners, I had to manually adjust my reluctor wheel very slightly in order to bring it back in range. It has held for over 20k mi of spirited driving.
Morning fellas
I turned the crank and that bk2 intake vvt isn’t making any noise, I can hear oil pumping out of it but I’m assuming that’s normal op? It won’t line up with the other 3 Cams tho. What do I do? Do I put everything back to get more data or do I start on that 1 vvt adj.
Here is my logic.
Engine OFF as tested by David : bk2 ( Bank 2 ) intake vvt isn’t making any noise, I can hear oil pumping out of it but I’m assuming that’s normal op? It won’t line up with the other 3 Cams If we assume the lock on that suspected VVT is good, the only way I see that it won't line up with the other 3, is because the reference to see it lining up is the TONE WHEEL .
So if TONE WHEEL shifted, David won't be able to align it with the other 3.
If chain too stretch at Bank 2, both Intake and Exhaust VVT will be out of alignment, because them two share the same chain.
V8 or V6, its the same for timing chain layout.
===================
David, you checked via method below, see at hole of cam-pos sensor the TONE WHEEL edge : Right ? PDF Attached as Check Position of Camshaft.pdf
You can also confirm by 1 more method, but you need to open up the VVT mini window like below : PDF attached as Cylinder 1 at 40 degrees after TDC.pdf
Here is my logic.
Engine OFF as tested by David : bk2 ( Bank 2 ) intake vvt isn’t making any noise, I can hear oil pumping out of it but I’m assuming that’s normal op? It won’t line up with the other 3 Cams If we assume the lock on that suspected VVT is good, the only way I see that it won't line up with the other 3, is because the reference to see it lining up is the TONE WHEEL .
So if TONE WHEEL shifted, David won't be able to align it with the other 3.
If chain too stretch at Bank 2, both Intake and Exhaust VVT will be out of alignment, because them two share the same chain.
V8 or V6, its the same for timing chain layout.
===================
David, you checked via method below, see at hole of cam-pos sensor the TONE WHEEL edge : Right ? PDF Attached as Check Position of Camshaft.pdf
You can also confirm by 1 more method, but you need to open up the VVT mini window like below : PDF attached as Cylinder 1 at 40 degrees after TDC.pdf
Happy wrenching .....
Yes I checked from the CPS port. So that tone wheel could be shifted and causing me to read the timing incorrectly? Should I remove that vvt cover to confirm good/bad actuator? If it’s just a shifted tone wheel what would need to be done, can you put it back in place lol?
The tone wheel you can set it back slowly to its zero or line position. Have to be gentle.
One member here has done so and he put micro welding so that it wont move.
You need to remove the camshaft to fix that.
Now you only removed the magnetic solenoid of VVT right , below : ? Otherwise how do you see the oil valve of the VVT
In short, to adjust ONLY the Intake tone wheel on that bank…you open oil filler cap, utilize your choice of implement (long flat blade screwdriver in my case), and some type of mallet. The VERY important thing is to be GENTLE, and also to insure you are delivering the force to ROTATE the wheel (clockwise), NOT to push the tone wheel tabs up or down AT ALL.
You want to look at your current measurements via scan tool, give a couple VERY gentle taps, then rescan and review new measurements. Once in the range, stop. If lucky, it will hold that position like mine did.
This is completely outside of WIS or any such instruction, and only provided as a do at your own risk idea. Failure will require camshaft replacement most likely
The tone wheel you can set it back slowly to its zero or line position. Have to be gentle.
One member here has done so and he put micro welding so that it wont move.
You need to remove the camshaft to fix that.
Now you only removed the magnetic solenoid of VVT right , below : ? Otherwise how do you see the oil valve of the VVT
I haven’t removed that I just hear oil coming out of it from the cps.
In short, to adjust ONLY the Intake tone wheel on that bank…you open oil filler cap, utilize your choice of implement (long flat blade screwdriver in my case), and some type of mallet. The VERY important thing is to be GENTLE, and also to insure you are delivering the force to ROTATE the wheel (clockwise), NOT to push the tone wheel tabs up or down AT ALL.
You want to look at your current measurements via scan tool, give a couple VERY gentle taps, then rescan and review new measurements. Once in the range, stop. If lucky, it will hold that position like mine did.
This is completely outside of WIS or any such instruction, and only provided as a do at your own risk idea. Failure will require camshaft replacement most likely
Interesting.. so first thing I’d have to confirm timing marks are all fine meaning I’d have to remove vvt covers. If all checks out, put everything back and try this?
Oil filler cap is on the opposite bank of this shifted wheel, if I adjust if from vvt cover removed how will I check measurements?
Apologies! I get the Bank 1 vs 2 thing crossed up darnit. I cannot very well advise you on that side, as I have not manipulated any VVT or tone wheel on that side.
I can only advise that if the parts in front of Bank 2 plate block its removal on your engine (as they do on m278)…there’s a LOT more work involved (rabbit hole). Hopefully it’s more spacious given smaller motor etc.
Also, at this point I think the decisions on best path forward must be made by you. How thorough, how much effort and expense, etc. A truly thorough job here may cost you $1-2k DIY, and would certainly cost you well over $7-9k dealer easily. You might get lucky with some shortcut…and you might not. I wouldn’t be able to sleep well without evaluating the timing situation fully. YMMV as they say
Yeah I’m not sure what to do. Im in it for about 5 grand so far and 1-2k would still be considered a good deal.. but will this fix both my issues? (Long crank and misfire). I could just run it back to the auction but I didn’t buy this to make money, I wanted to keep it :/.. we’re in the middle of moving shops now so I have about a week with my tools in the garage. If I don’t have it running by then, I’ll never have this much time to do so.
Based on what we agree needs to happen, let's optimize the steps... Bk1+2 camshaft timing marks
Bank2 Intake: VVT Gear + camshaft reluctor wheel
> The stunt we're trying to acomplish is not replace pricey camshaft that holds reluctor... we want not to damage anything in the process!
Normally this is fuel rail+ injectors+ sparkCOPs+ valve cover... we're cutting big corner in parts+ labor.
Choices are...
CPS port
VVT Gear cover
Both choices are good:
- Opening gear cover requires replacing "one-time-use aluminum" screws plus fresh RTV seal after cleaning both surface sides.
- Monkey port is much quicker for sure! More crank pulley work to position adjust, align, adjust, align...
You decide!
Opening VVT cover lets you see VVT alignment marks and check if VVT Gear are PASS: ( locked good) or FAIL: (lock pin wasted).
The limp tensioner is a must service part that leaks much needed oil pressure.
You will definitely know if VVT needed or not.
To that extent see what's next....
>> WEIRD !!
the numbers don't show Bk2-i being out of place and no correlation code!!! similar B1 vs. B2 numbers... from CPS
Gents: this means we're not done troubleshooting and need to pay attention to our timing marks assumptions... Opening VVT cover sounds like a real option if CPS port not matching.
we're missing a piece in that puzzle. *** I was gonna say perhaps ECU is using substitutions but no reason without fault code.
Last edited by CaliBenzDriver; Oct 25, 2024 at 02:08 PM.
2015 SL400 (M276 Turbo), 2014 C350 Sport (M276 NA), 2004 SL500 (M113), 2004 Audi TT225 (BEA)
This may be helpful. On my C350 with the M276 3.5L NA engine, the Left Cylinder Bank (Bank #2) IntakeCamshaft is actually near the upper limit for its position. It's still within boundaries, but barely. Still, the car runs fine.
Last edited by JettaRed; Oct 25, 2024 at 01:46 PM.
I think he meant that is as expected. We could NOT explain how the tone ring slipped, but the VVT was fine. One leads to the other one.
Low oil pressure -> weak chain tensioners -> VVT wears out -> tone ring slips
Yes, exactly right JC
that's the predictable MB setup we've learned to expect:
"One thing must leads to the next one!"
Ignoring VVT rattling leads to shifting reluctors for bigger repair job. The engine failures are expertly engineered.
Improve oiling to cancel this early on.
Last edited by CaliBenzDriver; Oct 25, 2024 at 03:19 PM.
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