[Diesel 10]

I have a new to me 05 C240. has 30k miles, and i feel it has a rough idle when in drive, and more so with the compressor going. i traded in my 98 e320 with 200k miles, and i felt it had a smoother idle at stops. my mother has a 02 c240 with 90k miles and is smoother as well. the car has a warranty still. i have taken it into the dealer, and they say it has no rough idle. i also feel the gas millage is horrible. about 15-17 in the city. but i also have a bike rack on which looses about 2 miles.....

another note is when i 1st got it, i ran chevron prem and the ideal was rough, so i switched to E85. same thing, no change. and i know you loose a gallon or 2 millage with e85


any ideas?

 

[kkalish009]

Are there any lights illuminated on the dash? Also, have you had any recent maintenance done (spark plugs, oil change, etc.)?

 

[Diesel 10]

Are there any lights illuminated on the dash? Also, have you had any recent maintenance done (spark plugs, oil change, etc.)?

no lights, the dealer said the spark plugs were good. they thought maybe a misfire. yesterday, i started it up. it died. (i forgot to say that happens at least twice a week) and then when i started it back up. tons of black smoke came out for a long time. then it went away and no smoke. i am at a loss, and i just bought this car (from the dealer), 30k miles and the "dealer" dosent care.

they are a bigger dealer in the area....

i do have a service B coming up. the computer says 30 days.

 

[kkalish009]

A few questions:

1) Regarding the black smoke, do you notice the smoke around the exhaust, and/or can you notice the smoke around the engine?
2) When you accelerate, is the acceleration hesitant?
3) When you come to a complete stop does the car hesitate?
4) Has the car shut off on you while you drive?

 

[Diesel 10]

A few questions:

1) Regarding the black smoke, do you notice the smoke around the exhaust, and/or can you notice the smoke around the engine?
2) When you accelerate, is the acceleration hesitant?
3) When you come to a complete stop does the car hesitate?
4) Has the car shut off on you while you drive?

thanks for helping....

1.) it was just one time, dark black smoke out the exhaust, i didnt pop the hood, i hope on a 05 there are no leaks. and it was just 1 time so far, that i noticed. maybe every time after it dies there is smoke not sure. but this one time i defiantly noticed it.
2.) car runs fine, no hesitant at all.
3.) when i come to a stop, sometimes it feels it feels it does, the engine is just so rough.
4.) no, just after starts.

the engine feels like it needs a tune up, but at 30k miles.

 

[kkalish009]

When you took your car to the dealership, was it a Mercedes-Benz dealership or a German shop? From what you've described to me it sounds like when the spark plugs were replaced they did not replace them with iridium spark plugs, but rather with aftermarket spark plugs, which have been known to cause idle problems on C240's.

Also, were the cabin air filters replaced?

If there was anyway you could try to video record "starting your car" it would really help me out to give you as accurate of a diagnosis as possible.

 

[rudeney]

One day, after cleaning the car, mine did this. After a quick check, I found that I had not securely replaced the engine cover after having cleaned it (with a damp cloth, not water). Anyhow, the MAF is very sensitive and without the drag of the air filters it was not registering the pressure correctly, but only at idle or return to idle.

 

[Diesel 10]

One day, after cleaning the car, mine did this. After a quick check, I found that I had not securely replaced the engine cover after having cleaned it (with a damp cloth, not water). Anyhow, the MAF is very sensitive and without the drag of the air filters it was not registering the pressure correctly, but only at idle or return to idle.

i just got this vehicle. 30k miles. i have no idea what it is doing. it could be so many things with these damn computers. i feel like its fuel. i now had a black smoke that kicks out the rear.

i feel its a fuel issue or spark plugs.