124 Tranny Lunka Lunka?

[dwighthinton]

I have owned a 1992 500E for the past 10 years. Now 145K miles. Still Love it. However, I continue to be curious about a mild condition that also existed in my wife's 124 300E. Occasionally, when decelerating... i.e. below 40 mph, the car experiences a mild surging which I call "lunka lunka". It is similar to trying to idle along in an old stick shift car at 5 mph in top gear...it sort of tries to lunge back a forth a bit... cannot reproduce it in front of my friend an MB mechanic. Does not matter which gear is selected...even does it in reverse...Most noticeable below 10 mph creaping along in traffic but it is still an infreqent occurrence.

Has anyone heard of this? Any idea what causes it?

[mbdoc]

ON deceleration, the fuel system shuts the fuel delivery ON/OFF at the injectors to control emissions. MOST likely you are feeling that. ON some cars you can even see the tach move 100 RPM when that is happening.

[dwighthinton]

Thanks for the prompt reply.
That makes sense... as simply applying throttle, eliminates the condition. I notice that the tach often jumps more like 500 rpm, up and down, up and down. Curious as to why the manifestgation is so intermittent. It can go all day or more without the sympton, surface for several minutes...in varying degrees of amplitude, and then completely disappear again for several days. Is this a common issue to (a) 500E's (b) W124's (c) Mercedes, or (e) ??

I don't recall the condition ever showing up in the 72 450SEL, 78 450SE, 84 380SE, 84 300TD, 2001 E-55, but I do vaguely recall it in the 86 300E.

[mbdoc]

Don't know WHY but on some cars, it is very annoying.

THE worst MB was the 1995 S320, MB came out with an improved computer when enough people complained.