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I have a new to me (3-4 months) 2009 ML550 that has been running great so far, no engine issues or CEL at all. However today it began shuddering/stumbling at idle, felt like a misfire, but no code. It drove fine home and I left for work a few hours later and it was way worse. In addition to the shudder at idle it would shudder under light acceleration. Heavy acceleration seemed to have no symptoms, but as I drove it back home (would not make it to work) it came to a stop about 20' from where I needed to park (shudders and slowed to a stop). The pedal would not do anything, engine would not rev or anything, car would not move. I put it in park, back into drive and then it was fine for a few seconds before it did it again. I got it into its parking spot and left it.
I ordered an Autel AP200 scanner, as I have one for my other car that seems to go pretty in-depth into codes and it should be here tomorrow. Anyone ever experience this or have any ideas on what this could be? I should not that this was a cooler rainy day... I am not sure if I have had a day like that since owning it and not sure if that is relevant or not, but wanted to add that.
Only maintenance I have done on it so far is replacing the oil cooler and gasket (was leaking into coolant), changing to G48 from G05 coolant, air filter replacement, and bleeding the brakes.
Hi so I had a lot of the same issues on my 2010 ML550. I chased all kinds of things but what mainly fixed problems was my air cleaner was not all the way pushed down and sealed and the silver clip on back by firewall was not fully clipped over air box. I also replaced the round gasket that is under air box so it seals correctly now and also replaced the bosch mass air flow sensor (not sure it needed it but all together helped).
I still have a very slight shudder at very low speed (usually on a small hill) but I took to shop and they said 8/10 550's all have that same problem, and its cylinder #3 compression issue that Mercedes has known about with lots of their cars even 2018 cars they said still have the issue, and they said most likely will never cause issue and just to leave it alone or do expensive valve job..... Stunning Mercedes never recalled these engines to fix all of this, but I guess they did on later models recently.
They did say they had some luck lowering the idle on some of them and the problem was almost 100% gone and you have to really be looking for it to notice, so that will be next for me.
Hi so I had a lot of the same issues on my 2010 ML550. I chased all kinds of things but what mainly fixed problems was my air cleaner was not all the way pushed down and sealed and the silver clip on back by firewall was not fully clipped over air box. I also replaced the round gasket that is under air box so it seals correctly now and also replaced the bosch mass air flow sensor (not sure it needed it but all together helped).
I still have a very slight shudder at very low speed (usually on a small hill) but I took to shop and they said 8/10 550's all have that same problem, and its cylinder #3 compression issue that Mercedes has known about with lots of their cars even 2018 cars they said still have the issue, and they said most likely will never cause issue and just to leave it alone or do expensive valve job..... Stunning Mercedes never recalled these engines to fix all of this, but I guess they did on later models recently.
They did say they had some luck lowering the idle on some of them and the problem was almost 100% gone and you have to really be looking for it to notice, so that will be next for me.
Well that is kinda sad to hear... Did you do anything with Cylinder 3 compression? That seems like that could be a major issue, right? Which side is Cylinder 3 on? My ML550 does have some paperwork saying a valve job was done on one of the heads and the head was replaced.
Was yours ever bad enough to the point where the car would not drive (before you did the MAF, air box fixes)?
No I have not done anything about it as the shop said not to worry about it as so many of them have the issue. I have 211k now and they said it will keep going for a long time. Maybe yours already had it fixed. No mine did not completely ever stop or drive. I was going to do the plugs next and the coils, but pulled a coil and they are fine. One thing you may look into is they have a bracket on the intake manifold that opens the flaps and they get carbon build up and the plastic arm breaks and causes hesitation, and sometimes (I believe) cause car to not go at all. Most guys says to order a new intake manifold and it comes with all the new parts, or they make a kit that also can repair the existing brackets (new ones are metal not plastic that mercedes used). But you still have to remove the manifold to replace the kit, but cost is way less than new intake manifold. I was going to do that but thats when I took to that shop before I threw more money at it, and they said no your bracket is fine, so I did not need to do it.
Here is the description so you can look up, lots of guys had this problem and you can order it on AZautohaus or others have it too
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
