Boom vang

My 1.8K has an intermittent idle issue:

Sometimes it is steady ~700rpm and other times it varies up and down by a couple hundred rpm as if someone is playing with the throttle i.e. goes up to 800 then back down to 600 then back up to 800 and so on every couple of seconds.

2nd problem:
from idle if I increase the throttle gradually no problem, if I quickly push it down the engine stumbles and then catches up to the correct rpm

Boom vang

No suggestions?

I thought that everyone was an expert on here

Adi_V

you have the M111?
i got the same problem... i thought i might have something to do with the spark plugs not being changed for the last 80,000kms on my car.

guys, any input would be helpful.
Thanks in advance

spyderpig

it's M271 1.8


Well I've heard that in other threads. what I've gathered is (in importance order):

-check intake filter first
-check spark plugs
-clean MAF sensor
-change fuel filter
-check for clogged catalitic converter

hope it helps.

dmatre

You haven't said if you've had the lower PCV hose recall done, but check this https://mbworld.org/forums/showthrea...light=campaign
and check the wiring harness below the cam sensors for oil (and pray that you don't have this problem) https://mbworld.org/forums/showthrea...light=campaign

dnlow

If your idle is flucuating at start up and then acts nomally after the car is warmed up, then this is most likely the problem. I had the same issue on my '05 c230 and this fixed the problem. And it was free, how cool is that.

Boom vang

Hose has not been replaced, unfortunately this recall is not covered by warranty in Canada as MB Canada says that this is not an issue.

Cam sensors were replaced under warranty

replaced new air filter

capt_paul

I beleive to some extent, the idle speed will vary a bit because of load (ac cycling, alternator load, engine temperature). I see my care idleing between 650-700 rpm. The idle is smooth and normal.

Now, if your engine is runningrough as well as the idle speed v arying, then I would be more concerned.

Boom vang

Seems that my 2nd problem corrected itself just out of the blue

I tried to do a search in resetting the throttle position sensor but could not find the link, if someone could tell me how it is done that would be great

bumpnzx3

https://mbworld.org/forums/c32-amg-c55-amg-w203/148135-makin-sure-c55-32-brothas-hooked-up-ecu-reset-smokes.html

if that doesn't work- check your connection between the airbox and throttle body- could be an air leak there and the engine could be pulling in unmetered air. also clean the maf with electrical contact cleaner.

Jeff Gonzales

To RESET the throttle Follow the following steps:

1. Turn the ignition key to the on (NOT start) position.

2. Press the gas pedal to the floor and HOLD for five seconds.

3. Turn the key to the "off" position (don't remove the key), then release the gas pedal.

4. Wait at least two minutes - don't do anything.

that should reset the throttle position sensor. Please try the above and report back.

HULKSTRONG

CAN SOMEONE PLEASE HELP ME I WAS DRIVING AND THESE LIGHTS RANDOMLY COME ON DOES ANYBODY KNOW WHAT COULD BE THE CAUSE ?