looking for some opinions on my 240d idle - PeachParts Mercedes-Benz Forum

mabbonizio · #1 11-25-2016, 07:28 PM

Hi All,

first of all, I really like this forum & my new to me w123! All the information i need to fix any problem seems to be floating around here and the car just gets better and better as I fix each of its little nagging issues from neglect.

Car is a 1982 240D Automatic with aprox 150k miles on it.

Issue:

I have pretty rough idle in D with my foot applied to the brake at a stop light.
I've adjusted the idle today and set it to approx 800 rpm with a digital tach. It is a *bit* smoother when idling in neutral or park but as soon as i drop it into D it gets pretty rough.

I adjusted the valves a while ago. This didn't do much fro the shaking but definitely made starting easier.

Ran two cans of diesel purge through it which did nothing.

I haven't checked the compression but the cars starts so quickly (as soon as I turn the key) even when its cold and shuts off so quickly that i'm guessing its within spec.

I'm debating buying rebuilt injectors but have read some pretty scary things about rebuilt Bosch injectors melting cylinders.

Any suggestions?

leathermang · #2 11-25-2016, 07:54 PM

Since you have a digital tach.... try cracking open each fuel line at the injector and note how much if any each bore it contributing its part to the power of the engine.. this is the equivalent of pulling one spark plug wire at a time and checking for rpm drop.
Be sure to anticipate the fuel leak... at idle it does not use much fuel.. so a bath towel should suffice... or just take that chance to wash the engine...
Look carefully at your engine mounts... they can be cracked and it be very hard to SEE it...
Your engine is allowed to have an engine shock absorber ... perhaps two.. check on that.. .if you do not have even one.. there are instructions on how to retro fit one in the FSM.
Only if rpm drops are not the same for each cylinder would I mess with the injectors.