Don C230

I have a 1997 C230 (89K miles) that "hesitates" or "bogs" during "hard" acceleration whenever the throttle is depressed quickly over 2/3 open. It's almost as if it's not getting enough fuel.
Slowly easing the throttle will allow smooth acceleration, but no "passing gear" higher RPM (above 4K RPM) without hesitations.
I have replaced the Cat Converter (check engine light had come on - after replacement the light went off), spark plugs (there was some improvement), fuel filter, and air filter.
Funny, service tech says that no codes are showing.

Other than that, the car returns the same MPG as when new, starts easily, shuts off cleanly and runs smoothly.

Any advice would be appreciated.

Thank you,
Don

sph17

It sounds like your car on hard acceleration is throwing an error code that is causing your computer to go into "limp-home" mode and run on two cylindars.

I had a similar situation with an earlyer year 220. Under hard acceleration, from 0-60 my car's check engine light would come on and the car's computer would switch over to the "limp-home" mode with only two cylindars firing. In limp-home the car had no power and would often die at idle. Turning the car back on (or shutting ity off and truning it back on), would cause it to go back to "normal" with the check engin light on untill cleared by the dealer. Dealer worked on the car 4 times w/o finding the root problem. At first the oxygen sensor was replaced, as that was the error code. They started replacing other parts, and the last time they brought in a MB factory rep who directed their fix, w/o success.

I always thought it could have been the cats, as E-39 BMW's have a similar problem, that they traced back to failing cats, but since you replaced your cat w/o solving the problem, now I am not so sure.

If you find a solution, let us know as I would very much like to know what was wrong with the W-202 I use to have.

Don C230

"It sounds like your car on hard acceleration is throwing an error code that is causing your computer to go into "limp-home" mode and run on two cylindars"


Yep, it does "feel" like it's running on two cylinders. But the check engine light doesn't come on (since replacing the cat), and no "codes" seem to be recorded - could it be coils, and can they be "checked"?

Don

steve1173

I have an 03 CLK500 with 700+ miles last week with 550 miles the car hesitated & stumbled & on came the check engine light. Took it to my dealer who said the computer said the #1 cyllinder is missing so they replaced the coil on that one & soon as they did the miss went to #4 & moved around. They repositioned the crank sensor & the car did not run like before but no check engine light. Now 150 miles from that I put in drive it hesitates & stumbles & on comes the check engine light. To the dealer tomorrow. Any ideas of what could be causing this.

delta

My car had the same symptoms before.....although mine was a 97 E320 inline 6. I replaced the Mass Air Meter and the hesitation went away. Good Luck

Don C230

Thanks to all who took the time to respond to my earlier request.
After going through all the easier (and least costly) fixes, I did have the mass air sensor replaced (the timing lined up with the transmission being replaced under extended warrenty, but that's another story). Not only did it "fix" the problem, but the car's drivability is better than ever.

Thank you all again,
Don