Noviceguy

We are having problems with my wife's 2000 ML320 with 60,000 miles on it. I'm wondering if any one has any suggestion on what could be the cause of the engine warning light and strong vibrations from the engine especially when the car is brought to a stop stopped. Putting the transmission into "P" reduces the vibration ony by a bit. When in motion I notice less vibration than in "P". Shifting to "N" doen't eliminate the probem either. We've had this vibration problem for 2 weeks but the check engine light only came on yesterday when the vibrations were more severe. The SUV is OK otherwise.
I would really appreciate your thoughts on this.

Radomir

sounds like it could be the MAF sensor... but you'd really wanna check the error code to see what triggered the CEL to come on.

Noviceguy

That's interesting because I just had a new MAF put in my C class a couple of months ago. Is the MAF a very fragile component or am I very unlucky?

GDawgC220

the MAF is fragile...or better yet, the sensors inside the MAF are sensitive. Possible something slipped through the air filter and made contact with the MAF and caused it to die.

MAF's are a common thing that trigger the CEL and get rough vibrations and slow pickup.

OttoBon100

When my check engine light came on recently it was only a short while later that the engine started running roughly but I was able to make it to work. When I left work ran fine briefly then same thing and about two miles down the freeway I had no power and pulled off the freeway. I ended up being towed to the dealer and it was a plugged catalytic converter. '99ML 320 with 61k miles. Warranty covered it. Luckily we weren't in the middle of nowhere. I would get it in and get it checked. I had an MAF go bad on my wife's C280, kind of the same indications but not as severe.

Noviceguy

Thanks Ottobon. My C class's MAF engine problem was not as noticable either. It was mainly difficulty with starting. Thre was no vibration. Seeing that it could be the catalytic converter I will definitely bring it in soon. ( By the way the CEL is now off and the vibration does not seem as bad. These changes (temporary?) were brought on by simply refilling the gas tank.) Any other idea out there?

c1pinang

I just had the problem last week. Definately the mass air meter. Brought it to the dealer it costs around $450.

Noviceguy

So it's probably the MAF or catalytic converter. Thanks guys! I will give you all a progress report after a visit to the dealer.

mbtech208

It could be the mass-airflow sensor. A more obvious cause could be a misfire, with the check engine light and rough running.

Noviceguy

thanks Dave, that's what it feels like. what would cause an engine misfiring? mass air flow sensor? catalytic converter? spark plugs? anything else?

drummerboy

You can unplug the cable from the MAF Sensor! If it improves...you've got it.
You can check my posts regarding the MAF!

rizwan

this might be sacrilegious to a Mercedes forum, but I a similar problem on a Toyota - less vibration on idle, but on D it vibrates a lot, as if the RPM is *just* above stalling. It started as a very slight vibration, and i let it go on until it was basically stalling the car when it was idling.

The problem? An vacuum leak in the fuel induction system was causing air to leak out and fuel to pass intermittently to the engine. It's worth a try to see...

regards,
riz

Noviceguy

Thanks Rizwan. So far all advice seems to point to serious causes that are best handled by the pros. We are bringing the car in at the end of next week. Will keep everybody posted.

Noviceguy

Just got back from the dealer. It WAS the MAF! The dealer fixed it under major warranty at no cost... This was a pleasant surprise. It would have been $582 Canadian. ( over $400 USD ) After reading all the posts I had a strong feeling it would be the MAF. I was tempted to buy the MAF and plug it in myself but am glad I went to the dealer for this one.

Thanks to all who helped. You guys are good!

Noviceguy

Weaker vibrations continued after the new MAF was replaced. Another trip to the dealer revealed 2 faulty spark plug cables and 2 spark plugs. Also malfunctioning tachometer (stuck at zero for the first few seconds after engine start up) not mentioned previously was related to the faulty cables. Trip computer is dead! Unfortunately both problems are not under warranty. Because of a shortage of parts at the dealership these problems have not been fixed yet. Does any one know how difficult the sparkplug job would be?