S 320 CDi intermittent rough idle

[MB-Graham]

Hi,

I have noticed recently that my 75k mile 2005 W220 S320 CDi sometimes idles roughly when stationary in traffic etc, nothing major but I can feel it 'missing' occasionally.
I drove it home today, left it running for a couple of minutes and I'm sure I heard a noise (possibly a click) from under the bonnet and the car then settled down and idled perfectly !

Does anyone have any ideas ? It doesn't do it every trip and seems more noticeable when the weather is warmer.

Thanks in advance, Graham.

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[merc85]

Thats a strange one? how long has it been doing that? my 3.2 Cdi is smooth all the time.

Does the rev counter fluctuate? Maybe worth putting a Injector cleaner in the next time you get some fuel.

 

[MB-Graham]

It's been doing it since I've had the car mate, I've run a cleaner through and it doesn't seem to have made much difference, could it be the timing chain becoming loose ?


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[MB-Graham]

.....rev counter doesn't fluctuate, it's not bad enough, I can still feel it though.


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[merc85]

It wont timing chain if it was loose enough to do that it would rattle. I take it Star didn't bring any codes up?

 

[MB-Graham]

It wont timing chain if it was loose enough to do that it would rattle. I take it Star didn't bring any codes up?

Nope, no codes relating to injectors etc

 

[merc85]

Could possibly be a idle control valve starting to act up i suppose, Mine has had one on it in the past.

 

[MB-Graham]

Anyone else have any ideas.....


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[dddooommm]

Egr system.
Spray some cleaner through the system. Wynes egr / turbo cleaner.

 

[Alex Richardson]

Your car looks very clean. So I don't think it's an issue of dirt or dust. Must be something with the heat, cause you mentioned about the weather. I'm sure mate.

 

[zipdip]

I think the EGR,I have the later model,and the large silver pipe at the front of the engine was filled with soot,I must admit you nearly always find that you get power loss,but just maybe you have the first symptoms,if you are handy with a spanner then removing and cleaning is not hard,but maybe a visit to a indy maybe the best course of action

 

[merc85]

Those egr valves can be a ass to remove as they get seized in.

 

[MB-Graham]

Thanks, it also seems more noticeable when I have been driving the car 'hard' for some reason.


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[MWCLS]

Can't help with the cars problem, but it looks stunning.

 

[MB-Graham]

A bit more info on the symptoms.

Took the car to work this morning (10 miles) and the car was smooth and idled well.
Drive home the scenic route (20 miles) and noticed a very slight roughness to the idle after the car had reached normal temperature, when I restarted after getting some of Shell's finest V Power the car was back to a perfect idle for a while then after a while a very faint roughness again.

Could this be the start of EGR problems ?
If so (and as I have a mapping session booked) should I....

a) change it
b) leave it till it gets worse

All help appreciated.


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[merc85]

If the rpm doesn't fluctuate and the car drives fine, perhaps as suggested it could be worn engine mounts. They are due for a change at around that mileage.

 

[500easy]

Egr system.
Spray some cleaner through the system. Wynes egr / turbo cleaner.

hello dddooommm... been trying to message you.. do you still have the sil arrow wheels... been looking for a set ... thank you

 

[dexross]

A bit more info on the symptoms.

Took the car to work this morning (10 miles) and the car was smooth and idled well.
Drive home the scenic route (20 miles) and noticed a very slight roughness to the idle after the car had reached normal temperature, when I restarted after getting some of Shell's finest V Power the car was back to a perfect idle for a while then after a while a very faint roughness again.

Could this be the start of EGR problems ?
If so (and as I have a mapping session booked) should I....

a) change it
b) leave it till it gets worse

All help appreciated.


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Hi graham, any update on how you rectified this problem as mine has started doing the very same as yours, identical issues, now done 70k still drives very smooth, or in crawling traffic only sometimes slight missing,