1990 300E hard start, rough idle
 

I have the MB, real nice shape!

There are a few bugs that need to be taken care of, the worst is hard starting and a rough, low idle, (just over 500RPM on the tach). I am just getting familiar with this engine and its components The engine is a 3.0, it has an automatic. The car seems sluggish on "take off" that I think may be due to the rough low idle. Is there an idle adjustment or is this taken care of by a module?

Any helpful information will be GREATLY appreciated.

TIA,

Michael

RE: 1990 300E hard start, rough idle
 

Bumped to the top

RE: 1990 300E hard start, rough idle
 

you may have problem related to fuel system.

the fuel distributor often gets faulty if you don't replace the fuel filter in time.

a battery of tests must be done to find the source.

do fuel pressure, cylinder comparison, and compression check first.

RE: 1990 300E hard start, rough idle
 

I know I like to hear the outcome of a problem/issue. Here's mine.

I changed the plugs, oil/filter, fuel filter, air filter, changed out all those aluminum fuses for copper, found a burned out fuse behind the battery (10 amp, spade type). The car now runs like a "top"! Front brakes too! I plan on doing the trans fluid / filter this Monday, as well as brake fluid.

I believe the 10 amp fuse did a lot to change things...including turning off the ABS light.

The aluminum fuses are very poor as they oxidize badly, I have heard there is a glass replacement, I did not find them so the copper ones will do till I find the glass ones. Please "chime in" if you know a source.

Michael

RE: 1990 300E hard start, rough idle
 

yup it sounds like you change a fuse in your overvoltage protection relay. wash your abs light on? if it was you need to tell us that. that is a common problem on mb cars in the 80s and 90s if that fuse blows the car not only runs rough it turns on the abs light.

RE: 1990 300E hard start, rough idle
 

I know I like to hear the outcome of a problem/issue. Here's mine.

I changed the plugs, oil/filter, fuel filter, air filter, changed out all those aluminum fuses for copper, found a burned out fuse behind the battery (10 amp, spade type). The car now runs like a "top"! Front brakes too! I plan on doing the trans fluid / filter this Monday, as well as brake fluid.

I believe the 10 amp fuse did a lot to change things... [&:] :eek:including turning off the ABS light.[&:] :eek:

The aluminum fuses are very poor as they oxidize badly, I have heard there is a glass replacement, I did not find them so the copper ones will do till I find the glass ones. Please "chime in" if you know a source.

Michael