victorb623

I have a 2003 c240 with 53,000 miles on it.

I recently changed my spark plugs and MAF last month. However the shaking during idling is still there.

No check engine light on. What do you guys think??

It runs perfect except at idling its shaking / vibrating a bit (you know something is wrong)

Could it be one of the coil packs? or one of the coil wires?

Thanks. Your response will be most appreciated

Glyn M Ruck

Please get an OBDII scanner & check for stored codes. We need to see if you are storing misfires or something else not sufficient to trigger a CEL.

Slight engine shake is usually plugs. Did you use the correct OE Bosch plug? If not plugs then next is usually wires & coilpacks.

Finally check CPS

Very rarely on M112 engines it can be engine mounts X 3 (includes rear tranny mount)

Did you use a genuine & correct replacement MAF - Part number is on the black plastic cover. Sometimes VW/Audi MAFs are sold on the internet. They look identical & fit but do not work properly on a Merc.

Smallbodybenz

It could also be your idle sensor.. i had a similar prob although i have a m111

victorb623

BTW my engine is M112 v6.
I checked it using an OBDII scanner. No codes. I used Bosch OEM plugs. I think it might be the coil packs and wires. CPS was changed 2 months ago.

Will also check idle sensor.

acr2001

Could be your engine mounts. Have to figure out if it's the engine that's creating abnormal vibrations, or if the normal engine vibrations are transferring into the chassis because of bad mounts.

Glyn M Ruck

Sorry - I changed my post - I meant 112 engine. Mount problems are common on M271