hi -

i have a 1992 400E with just under 106K miles. in park the engine revs fine until it gets to about 4500 rpm, then it starts missing in a big way. it shakes the entire car. i was having the a similar problem when the car was on the road (it's off for the winter), although at a lower rpm. it just felt like a little hesitation every once in a while - not a big deal but noticeable nonetheless. the plugs look good and we replaced the rotors and the caps, but not the ignition wires.

any feedback is appreciated

How about don't drive it above 4400 RPMs. I don't think I've ever had mine over 3,000.

Two things come to mind - ignition problem, fuel problem. I know, it doesn't leave much else

I had a problem with one of the coil wires of the S420 resting on a bolt head. You could see where arcing had taken its toll on the insulation. The car would buck in higher rpms under load.

Could also be a restriction in the fuel system like a clogged filter.

Some recent MBs have a rev limiter when not in gear. I don't think the engine goes into convulsions. It just won't rev beyond a certain point in P or N.

Sixto
95 S420
87 300SDL

thanks for the feedback....
i normally do not make it a habit to rev the engine, but there will be times (like when the engine downshifts during a passing maneuver) when the engine will need to rev, perhaps past 4500 rpms......

if it were a fuel supply problem, wouldn't it occur throughout the entire rpm range? when it was at the shop, the ignition wires were supposedly checked to see if anyone of them was bad - they were all good.

i will call the local benz dealer to see if they can tell me whether or not the car is equipped with a rev limiter.

thanks for your help

A fuel line can be restricted yet allow some flow. If your fuel system can flow only half of what it should, you'll have no trouble cruising which probably takes all of 25 hp. Step on the pedal to merge between semis and there isn't enough flow to support 250 hp.

Has the wiring harness been replaced? Do you get random check engine lights?

Sixto
95 S420
87 300SDL

sixto -

i guess i will have to have the fuel line checked. i do not get any warning lights on the dash. to the best of my knowledge, the wiring harness is original. is there any chance i have a bad ignition coil pack?

thanks for the feeback