black smoke, EGR valve and idling speed

poseidon

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Jun 4, 2006
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Location
Aberdeen
Hi,

My car has had some black smoke on acceleration for some time. It has been getting worse in last weeks.

I did not want to go (and pay) for diagnosis to "experts", considering previous experience.

I directly bought EGR valve (£376) from the dealers.
The replacement is 6 minute job (including disconnecting battery which I did not need) on the driveway. I do not remember any simpler job. It is easier than replacing a wheel. The old EGR valve looked good on first sight.

The car is much better now. There is no black smoke. The engine is quieter and pulls better at low RPM.

Also, I discovered that it now always idles at 750RPM. Previously it wold idle at higher speed of 850RPM, even when engine is hot, and rarely it would settle at 750rpm.

I hope this helps somone.
Does anyone know how the idle speed setting is determined?

Regards,
Pose
 

S.Speed

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Apr 12, 2009
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Lancashire
Your Mercedes
Older Citroen Now :-(
Hi,
Does anyone know how the idle speed setting is determined?

Regards,
Pose

I believe the idle speed is determined by the ECU..
Gone are the days when you could turn a screw to alter the tickover RPM
 

mersum1es

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Your Mercedes
W212/-09/350CDI, W219/-07/320CDI, EX:W220/-01/320CDI, EX:W211/-04/320CDI, EX:W210/-01/270CDI
I believe the idle speed is determined by the ECU..
Gone are the days when you could turn a screw to alter the tickover RPM

Yep, now you connect laptop and set the revs, so laptop is just only updated screwdriver?
 
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