81 300D

I've seen alot of discussion on engine running rough and pinging/clattering when RPM's raised. The advise was it most likely is an injector problem.

I have just the opposite problem. My engine runs smooth as silk above 1000 rpm, no misses that I can tell.

However, when rpm drops to idle then I hear the pinging and nailing, it also starts idling rough, jumping and missing.

Same problem? Anything particular I need to look into? Or Should I just expect this with 240k mile engine?

Note: I did disconnect each injector, one at at time while idling rough. I could tell the engine would run even worse on each one, so each must be all working, the pump was pumping, however, when I disconnect 1 injector I didn't hear the Ping as bad.
I also ran LM diesel purge thru it, no change.

Thanks

Try to listen and see if it is one in particular. If so, you may want to try to replace the injectors first.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

I don't think very highly of Lubro Moly products. Try a bottle of Red Line Diesel Catalyst and see if that helps. I've always been impressed with their products and use them religiously in all of my cars. I tried LM's Diesel Purge in my old 240D to try to cure injector ping under load and nothing got better. Ran a bottle of Red Line in it and no more pinging! Great stuff!

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Rgds,
Aaron Greenberg
MB technician
Precision Motorcars, Cincinnati, Ohio
'67 250SE Cabriolet
'77 450SL
'80 300SD
'85 380SE
'89 420SEL
'93 300E 2.8
'74 Jensen Interceptor Mk.III
'81 DeLorean DMC12
'85 BMW 745i Turbo

Aaron's post parallels my experience with my pinging and vibrating 240D at low RPM, but I don't think my engine was missing. I added a bottle of the Red Line catylist (bought from this site) and no kidding, she calmed down by the end of the tank of fuel. Started to vibrate again within a thousand miles, but that proved to be a bad motor mount--maybe caused by all that vibration before Red Line?

Hope your problem is so simple!