2010 s212 e350 intermittent high revs before upshifting

[Will84]

Hi, I’m wondering if anyone has any thoughts on my issue, which is that my e350cdi sometimes revs up to the 3000rpm range before it will think about changing up a gear. Sometimes I can use the paddles to manually upshift, and if I I select manual shifting I can do the same. I’ve read various other threads but none seem to be quite the same problem.

I would say this happens about 50% of the time when driving the car and has been going on intermittently for the last 1.5k miles. I have icarsoft and there is nothing relevant coming up there, and I also had a dpf clean recently and that made no difference. I’m confident my issue isn’t the dpf clean mode kicking in.

I see people cleaning the maf and replacing seals to that section but I’m not sure if that is something I could do myself. Ultimately it’s a second car now on177k so I am loath to spend huge amounts on it chasing down faults - on the other hand, it’s still a great car and I think it should have many years of life left in it!

 

[Tonygw]

Hi there, when did the gearbox have its last oil change? maybe its due a service?

 

[Will84]

Thanks, yes maybe that is it. I got the transmission oil changed about 2.5 years/12k miles ago, but who knows, maybe there is a leak or it wasn't filled correctly at the time. As someone else said, its probably the only 'cheap' thing to try...

 

[DrNick]

Two things I've had in the past that have caused weird changes
1) Pinhole leak in a pipe allowing ATF out, resulted in odd behaviour for a while that got worse over time ( a couple of months), so checking fluid level is a good start.
2) Air leak on the engine inlet side caused lack of power resulting in the engine revving higher before changing. Had any work done recently that could have caused an inlet leak? On mine the glow plugs were changed and they loosened the inlet manifold for some reason and didn't tighten it back up!

 

[Will84]

Thanks for those suggestions, that's very helpful. I haven't had any work done recently, a service a month ago, but then the problem was ongoing for long before that. I'll definitely check the fluid levels though. Maybe just a top up rather than a full oil change would give me an idea of whether that was the issue?

I imagine that icarsoft could give me an idea of of an air leak maybe? I'll have a look again for codes.

Thank you!

 

[chinnybang159]

Hi Will,
Did you ever get to the bottom of this? Having a similar issue with my 2010 E350. Not shifting gear until 2k revs intermittently. Last night it wouldn't shift to 3k revs even trying to shift manually wouldn't work and downshift was very sluggish and jolty!

 

[phobos]

Hi Will,
Did you ever get to the bottom of this? Having a similar issue with my 2010 E350. Not shifting gear until 2k revs intermittently. Last night it wouldn't shift to 3k revs even trying to shift manually wouldn't work and downshift was very sluggish and jolty!

Does the issue go away for a while after your stop / start the car? If so, your TCM might need attention. I would get it scanned with an MB Star and read the transmission codes.

 

[Will84]

I'm glad I got a prompt to reply to this. I think my issue sounds/sounded very similar to that of chinnybang. I got the transmission oil changed, all of it, and the filter, and the problem went away - or so I thought!

I drove the car for two or three weeks after the transmission oil change and it was perfect, until one trip when it went back to it's old habit. However, since then it has been fine again.

With regards to the issue going away, before my transmission oil change, I was able to clear whatever code it was on icarsoft and it would be fine again, for a bit. Finally, mine seemed to have two 'modes' - high-revving and not upshifting, but allowing me to upshift manually, or high revving and not upshifting, and not letting me do it manually either.

Phobos, what is the TCM? Apologies for a basic question.

 

[TeddyRuxpin]

DPF regen issue?

What is the car idling at when it's doing the high shifts?

 

[phobos]

Hi Will - TCM - transmission control module.
There were to be loads of issues on the earlier 722.9 TCM, like 2005-2008. were some of the sensors on the TCM would die and cause issues like this.

You would get errors on the TCM like " The signal from component Y3xxxx ( Internal speed sensor) is not available.
It normally starts slowly and gradually gets worse with time.

As yours is a 2010 and a S212, it should not be affected by this, but I would still get is check with a decente code reader, ideally a STAR.

 

[Will84]

Thanks Teddy - yes it has the same feeling as a DPF regen, but probably even higher revs - you'll be cruising along at 30mph with 3k revs.

Phobos, thanks for that info re the TCM, that's interesting. I'll definitely get it onto STAR at some point. Fingers crossed it has settled down for now.

 

[TeddyRuxpin]

Hi will - but when it’s doing this and you stop at a traffic light, where does the rev counter idle?

 

[Will84]

Stopping at a traffic light or similar, the revs would drop down to where you'd normally expect them to be - 1k or so?

 

[E55BOF]

Should idle at about 600-650 rpm, more or less. 1000 is too high.

 

[TeddyRuxpin]

Both OM642 revisions should idle at about 550-650rpm under normal conditions, and 750-850rpm when cold or during DPF regen, which is why I was asking.

I wouldn't rule out an issue that stops the car from regen-ing properly, and therefore it keeps attempting it.

 

[Will84]

Ok, maybe I was idling lower than 1k then - whatever level it was, it wasn't high enough to seem unusual. However, interesting point about the DPF regen - thank you. That could explain the intermittent nature of the issue I suppose.

 

[chinnybang159]

Does the issue go away for a while after your stop / start the car? If so, your TCM might need attention. I would get it scanned with an MB Star and read the transmission codes.

After I park up and let it rest for even 10 mins it could be fine again and will drive as normal. I had a pressure sensor replaced in the DPF as EM light came on. But the original issue has come back again since then, just once of course. No gear change below 2k revs and car sounding louder than normal from back of engine. Will bring for diagnostic tomorrow and see if any fault codes show up.

 

[phobos]

After I park up and let it rest for even 10 mins it could be fine again and will drive as normal. I had a pressure sensor replaced in the DPF as EM light came on. But the original issue has come back again since then, just once of course. No gear change below 2k revs and car sounding louder than normal from back of engine. Will bring for diagnostic tomorrow and see if any fault codes show up.

Great, sounds like a plan! Keep us posted.

 

[Will84]

Hi all, just to close this out, it was the EGR valve. I took the car to Mercedes dealer in the end, and while they charged me two hours to diagnose, and then had me wait six weeks for the part to come from Germany, it did the trick. Apparently there was also a pipe attached to the EGR valve that was full of soot/gunk which they had to clean.

I was convinced it was something to do with the orange seals around the MAF area, as I had/have a spray of oil from there. But the garage assured me that was fine, and they seem to be correct. Fingers crossed!

 

[MrGreedy]

Thanks very much for coming back and updating.

As I was reading this, I was thinking something engine limp mode related was a strong possibility, giving the gearbox shift as a side effect and possibly throwing diagnosis down a red herring blind alley of something to do with the gearbox.

Glad it’s sorted; the EGR valve, cooler and intake manifolds can get very gunked up over time!