New C240 rough engine problem. - PeachParts Mercedes-Benz Forum

ducatista · #1 10-17-2002, 10:43 AM

Takes forever (30 min.) to warm up, stumbling and jerking under any acceleration. Once warm, still has a noticable hesitation/stumble at 3500 rpm at 2/3 throttle. This problem was not apparent when I took delivery, but over the last month or so has gotten increasingly worse. Now have about 2500 miles on the car.

Any ideas?

#2 10-17-2002, 03:00 PM

You car is new and under warranty w/ a free loaner car. Take it back to the dealer and tell them you don't want to see it again until the problem is fixed. Also, if you start tweaking with the car, MBZ may not honor the warranty.

#3 10-17-2002, 03:24 PM

John offers excellent advice. The problem is in the manifold resonance system. In case you're not aware, one of the subsystems of this engine that contributes to the extremely broad power band is this manifold resonance system.

Using a set of valves, the intake system is basically tuned by changing its length depending upon RPM range. This is basically like tuning an organ pipe. When it messes up, it is usually when cold, new and under open or partially open throttle.

They will most likely determine which set of valves are at fault and replace them. This is no big deal, from time to time these things come out of the factory faulty.

I'm sure your dealer will fix it right up.

Good luck,

royaiii · #4 10-17-2002, 05:24 PM

I have had multiple loaner C240s and they all have this problem. I attributed this to the very small displacement of the motor. I like these C's alot, the chasis is the best out there.

ILUVMILS · #5 10-17-2002, 08:43 PM

If the resonance flaps are the problem the intake manifold needs to be replaced( the flaps/valves are inside the manifold and can't be serviced ). I doubt that's the problem though. Either a bad fuel pump or the engine management ( ME-SFI 2.8 ) control module is no good. Another possibility is moisture/corrosion in the connector for the Crankshaft Position Sensor. There have been service bulletins concerning this but I have yet to see it. Fuel pump or ECU. Keep me posted.

#6 10-18-2002, 06:44 AM

My C240 exhibited this problem within 3 months and 5,000 miles of new. They replaced the entire resonance system and the problem went away. I do realize that there are always many things that can cause the same problem, but it seemed to be routine to them.

Additionally, the comment about the small engine. This engine is small in displacement, but amazingly powerful with a very broad power band for such a small engine. Mine makes power that many larger engines could only dream about. There is technology in this engine that was only found in Formula One cars not long ago. As far as I'm concerned this engine is an engineering masterpiece. It also has been out there long enough to prove itself not to have any of the achilles heels of many other engines, including the later model inline six engines such as the 103 and 104.

Stick to your guns and whatever the problem, I'm sure your dealer will get it fixed.

Good luck,

ducatista · #7 10-21-2002, 08:16 AM

who responded. There definitely seems to be a theme to your responses. I love having information before I go into the dealer. I'm scheduled for this week, so I'll repost with my results.

Eric.

Behind the Star · #8 10-21-2002, 03:57 PM

I have seen multiple problems with egr valves on 112 engines causing a problem similar to this.
Brian

#9 10-21-2002, 07:10 PM

My had the same problem, it happened twice so far, could be intermittent. I will have them check soon when the 20k miles is due at the end of the month.

ducatista · #10 10-25-2002, 08:18 AM

Dropped the car off at the dealership yesterday with a list of 5 things that might be causing my problem (Thank's guys!) and asking for a report on each item. Did not hear from them all day. Finally, called, but service "advisor" not available. I have to go, so I decide to drive to the dealership to see what the status of my car is. Get there, and the "advisor" says, "Gee, didn't you get my message? (Now mind you, I'm a Headmaster at a good sized school. I've got an assistant who catches all of my calls, and NO CALL came from R&H Mercedes during the day.) We couldn't find anything wrong with your car, so we didn't do anything."

I told him to keep it overnight and try in the a.m., that I would not take the car until it was correct. So, well, see. Consumers have quite a few rights under the lemmon law, and I'm not afraid to use them.....

Eric.

#11 10-25-2002, 08:31 AM

You will have to continue to press them. You are dealing with an intermittent problem and they will have to drive it until the problem surfaces while THEY are driving it.

Whatever you do, don't let them charge you for anything. Keep after them until it happens while they are driving it and get your regional MB rep involved if necessary.

Good luck,

ducatista · #12 10-28-2002, 08:14 AM

After telling the "advisor" that I wouldn't take the car back until they had correctly diagnosed the problem (all very calm and professional), the next day he gave it to the shop foreman. The foreman drove the car off and on during the day. When I got there that afternoon, he came to meet with me and said: "Boy, you've got a problem. Needs a new fuel management module." Of course, that was one of the four or five items I left with them as possible causes of the rough running at specific rpm (thanks again, guys!).

So, now they're ordering up all the parts and hopefully they'll fix everything next week.

Although I like the shop foreman, seems to be a "car guy," I remain extremely disappointed with R&H Mercedes in Owings Mills Maryland. Aside from my very first interaction with the dealer, I have had nothing but difficulties with their customer service and unwillingness to take care of business after the sale (For other issues, search under my screen name on this forum).

My AMG purchase in 2.5 yrs will not be from R&H.