Octane116

I have a 2007 SL55 AMG with roughly 27,000 miles on the car. I traded my SL500 in on this early last fall. After spending on a little time driving the 07, I noticed that while holding the car at a steady cruising speed, there is a feeling, which is confirmed by the tach RPM, that the car is surging. The RPM change is only about 100 to 200 RPM which is odd to say the least. It does it with the cruise control set too. I am not overly anxious to take to the dealer because I have "handled" quite a few time by my local MB dealer. In talking to a MB Service Manager in another state, he was unaware of the cause or a recall and said, without an error code, "he had not clue". By the way, there is no error code. Can anyone help or suggest where to start looking or how to solve the problem. Thanks much.

bob55

Cruise Control problem?

j21importer

I have felt this before and have found that there was a metal vacuum line that had popped out of the grommet in the back of the intake. the metal tube is attached by a bolt at the drivers side valve cover. This is the only thing i can think of that i have experienced.

Octane116

Thanks for the responses so far. The car is back in Wisconsin and I am in Florida until late March, so in the interum I am going to have my son look at the posibility of the vacuum tube being disconnected or the rubber grommet damaged. As mentioned in my initial post, it does the surge in cruise control as well as when holding the throttle with my foot. So it is unlikely anything relevant to the cruise. Any other ideas to consider I would be happy to check them too. I do hope it is the vacuum line though.

Octane116

Seeing I will be heading back to my home state where the car is later this week, I wanted to bump this post back into view for possible solutions or things to look at. I have the vacuum hose idea from a prior response, but I am accepting all suggestions. Again, this happens WITH AND WITHOUT CRUISE CONTROL on. The tach also shows the change to be in engine RPM as the surge occurs.

IngenereAMG

After the vacuum leak, I would consider the fuel filter. I think most vacuum leaks would trigger a CEL.

7sistersl55

Hi Octane116,
I have the exact same problem and its been driving me mad for the last year, no codes either. Did you ever get to the bottom of it, any help greatfull appreciated,
Thanks
Jeff

Octane116

I have had not luck yet in identifying the cause of the problem. So far, all the suggestions from this site are those that would lead to a computer code, and there are none. Jeff, I have sent you a personal email as well as responded here. At this point, I am stumped and still looking for answers.

denny6651

Octane,
Same exact issue with my 03 E55. It has been a few months since there has been any activity on this thread so I was curious if you may have solved the issue? As you mentioned the fluctuation/surging occurs when maintaining speed (RPMS are at around 1100-1200 with light pressure on the gas pedal) then it starts surging ~200 RPMs. I am going to schedule an appointment at my MB dealer but without a check engine light, I am guessing that they will be guessing.
Thanks!
Denny

alx

clean your throttle body and have somebody with sds do a diagonstic on the tb motor

Octane116

I still have not had any success completely resolving the surging issue. I have talked to a bunch of AMG owners and dealers about the surging. It seems the ones that are conscious and alert notice the surge problem. The owners that would drive on a flat tire, wondering why the car pulls a little are the ones that DO NOT notice it!

I recently hauled the car to Detroit, 300 miles from my home, to a Mercedes dealer there I actually trust (I think the three dealers where
I live are all on crack). I had already discussed the problem with them. My local dealer told me to drive it until it quite. The dealer in Detroit was at least willing and open minded enough to go through absolutely everything on the car and not rape me. They could find nothing! They did change one setting in the ECM raising some reference in the ECM for fuel useage, from 91 to 93 octane, That being the only change I guess I can say it may have had a slight impact on the surging. Now it changes for a very noticable surge as before, to a almost non-noticable surge. But the event that cause those changes from more to less noticable to occur cannot be identified.

denny6651

Glad to hear you've been successful in getting some improvement on this issue. I can't imagine others not noticing this if it is happening to them but I guess that is possible.

I'm taking my car into someone that I believe will think out of the box on this next week. I will share some of the comments in this post with them. I'm also on the cusp of getting a tune/pulley/cooling upgrade. Part of me is hesitant if there is some type of problem (modifications could compound it) but I also wonder if they could improve the situation. Since MB doesn't seem to think this is a major issue at least, I will likely take the chance with the upgrades (this will happen next month).

Stay tuned. I will be sure to share results or lack thereof after visiting with a specialist next week!

cal1

My only suggestion is to post this on the E55/E63 forum. There are lots more people and many techs that know our 55k well. Maybe denny6651 already did.

cal1

I'm probably off my rocker here, but I notice an occassional surge like feeling that I am pretty sure is in the tranny. Just wondering what a sneaky reset would do. Could not hurt, that is for sure. Could this be a tcu issue?

7sistersl55

Hi Guys,
Any update from anyone on the cause of this problem, its driving me insane at the moment, I've changed a quite few things now and still no improvement??

denny6651

Mine was cured by having a new torque converter installed that has a higher stall (I believe it is now 2300). My torque converter was bad or believe to be bad and it was going in and out of lockup...For 100-200 RPMs it is difficult to say that there was a lot of bang for the buck in this exercise. It did drive me insane though and a psychologist may have been more expensive. :-)

I am now dealing with a vibration under low acceleration that I suspect is the motor/transmission mounts.

I use an independent mechanic and I take it in this Friday to have him look at that. This was present along with the surge and we suspected both were related to the Torque converter which was half right. We shall see.

For reference my 2003 E55 has 71k miles on it and a build date of May 2003.

cal1

Great to hear you got at least one problem solved. Your thought of motor or tranny mounts and the vibration source is probably dead on. I am betting tranny mount. My recall is bad motor mounts did not create as much vibration. In fact the first sign of bad motor mounts for me was that they were leaking. I did not notice any vibration at all. When my tranny mounts were bad, I had a vibration at low RPMS. I have had to do another round of new motor mounts. I guess the stage 3 mods made my car a bit too torquey or maybe it is the driver that can't quit grinning under WOT putting constant stress on the MMs.

To the OP, I still say a sneaky reset is worth a try especially after what denny6651 experienced.

Here is a link if you are interested https://mbworld.org/forums/w211-amg/...set-works.html

If nothing else, your car will start shifting better until it relearns your driving style.