zcct04

2006 C55 has been having problems over last couple months. When stopped or slow rolling at very low speeds without any throttle, car sometimes has a brief stumble, sometimes throttle surges and drops back, and sometimes dies. It’s dying about 3 or 4 times a week. It’s not throwing any codes or warning lights. It always starts back up immediately so I’m guessing its not a CPS problem. Dealer has spent days hunting but has not found anything wrong and has not been able to replicate the problem. Anyone else had similar problems? Any suggestions about how to diagnose?

loudandheard

I know people say not to throw money at problems that you are not sure of, but a cps replacement is relatively cheap and should be done for less than $200. If you do the work yourself, the part is around a $100 and takes a bit of elbow grease and ingenuity and you should be able to do it yourself.

Are you using a dealer, Alex Rodriguez by any chance? I have had great experiences with them.

zcct04

Thanks for the quick help! I too am using ARod and, unlike most of the dealership we read about here, they really have been good to work with.

My past expereiences with CPS on other cars, and most of what I've read, all have one thing in common - the car is usually unable to start back up until it has been sitting for a while. I considered this as a possibility but mine has ALWAYS been able to start back up immediately. Also, CPS also seems to strike randomly. My car's problem only happens when I'm slow or stopped with my foot off the gas. It's a pretty ugly feeling when you've slowed down to whip a U-turn and the car dies mid-turn and power steering disappears!

Are you down on the ARod side of town?

CLKCLK

CPS is not my first choice. If you like to spend some useful money that may help or fix the problem then here is my list

1) Injector cleaning addictive like Techron $6?
2) Spark plugs $80-$120?
3) Check the fuel filter, if it’s clogged $50
4) If it’s jerk when it shift then change the trans oil $150?

You may have already tried these, but it won't hurt

C43AMG

Mass Air Sensor

AMS Performance

MAS or possible vacuum leak some where in the intake system (after the MAS). Injector cleaner would certainly be recommended on any car 4 years or older, but that doesn't appear to be the issue here (although it may help alleviate the problem).

4 years for and MAS is about avg so it may be starting to give. Might not be a bad time to clean out / replace your airfilters as well. If you don't want to buy a new set, just tap out the old ones on a flat surface to get any loose dirt out and then just vacuum them on body sides w/ a shop vac.

hope that helps...

lkfoster

Doesn't the C55 have the filter integrated with the level sensor? I seem to recall it was something like $250.

TemjinX2

+1

I would start by cleaning the maf sensor. Its cheap and easy.

Then check for vaccum leaks.

loudandheard

I'm actually located in Spring, but I would drive to Arod if I had any problems with my car. They were the only dealership that would bend over backwards to take care of me and always got the job done, plus they give out loaners.

Listen to the people above, I have no experience with the C55 as I drive a C32. Good Luck, Maf cleaning sounds like the way to go.

alpha8a

Sounds like the same problem I had. I ordered a new MAF online and changed it myself. Has been driving perfectly ever since then. The MAFs tend to go bad after a few years.

91RS

How many miles? Seen this problem caused by a dirty throttle body in a bunch of different cars.

AMS Performance

Cleaning throttle body does help normally, however benz throttle plates never fully close. Idle is modulated by the plate itself so it shouldn't be an issue here.

You may also want to get an injector cleaning service done. Usually its about $150 but makes the car run like new. If you don't want to spend that much, just throw 1-2 bottles of seafoam in a half tank of gas and run the car hard... that should clean out most of the gunk in the system.

Tump43

I agree with AMS. I experienced the exact same symptoms for essentially that same reasons. This happened when I first installed my bored out throttle body. Apparently, it had not been modified correctly and the butterfly had not been changed. Once I had it re-machined and a new, wider butterfly fitted, the problem went away. The car actually started to run too lean, requiring an updated tune. Essentially, the car had been running with a vacum leak in the intake system that was remedied by changing the butterfly. I also cleaned the MAS and replaced the throttle body gasket at the same time. Perhaps your tb gasket is worn or your air box and other components leading to the throttle body are loose or not properly installed.

zcct04

We checked through all the warranty records today and it looks like the MAF is only a year or two old. Still can't rule it out based on the feedback above from others whose identical problem was fixed by a new one, but . . .

Anyone had problems with tourque converter failing? I'm wondering if it might have similar symptoms.

I am the happy temporary owner of a data logger that one of the dealership mechanics has loaned me. The car has been dying intermittently but it's now happening every couple of days and sometimes even twice a day. I'm hoping this will give us some better clues. I'll provide updates if we find anything, but in the interim would still really appreciate the ongoing flow of good ideas from the experts here!

loudandheard

Goodluck, I hope you have a warranty or plan on getting one.

zcct04

Problem finally solved. Cause was a bad electrical connection at the end of the cable from the ECU. Kudos to the team at A-Rod MB in Houston - they rock!

betrezra

WOW.... how did they discover that? Just visual inspection finally found the damaged insulation?

zcct04

betrezra,
I'm honestly not sure how they found the problem. Intermittent failures like this are always a *****. Lots of data logging and careful review of the symptoms led them to conclude that the problem was electrical and likely in the ECU circuit. The issue wasn't as easy as damaged insulation - it was apparently a multi-pin plug at the end of the wiring loom that wasn't making a good connection to whatever it was plugged into. Cleaning and tightening made an immediate difference and seems to have cured things. The C55 is fun to drive again, and the A-Rod team has really impressed me!