CLK 320 W208 performance / codes

steadyeddie

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Mar 7, 2011
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Mercedes CLK 320 W208
Hi,

So a few months back now I was chasing a gremlin that was causing my car to lose power and then judder heavily at idle.

I replaced the MAF, TPS, leads, coils, fuel filter etc to no avail.

I visited an independent Merc Specialist twice who charged me an hour labour each time. First time was just to read codes and second time told me I most likely had a blocked catalytic converter and wanted to charge £1,200 for a new exhaust.

Subsequently went elsewhere to have the cats removed. Car still had the problem and now sounds like crap. :mad:

Anyway...a couple of weekends back I was checking all vacuum hoses in the engine for signs of a leak. I tightened every screw / jubilee clip I could find.

SUCCESS! The car now no longer cuts power under acceleration or judders.

I have purchased an ODB reader and adapter and was able to read the fault codes, however I have not been able to clear them.

The car also still feels quite sluggish and I'm wondering if clearing the codes will help?

If it's not the codes I can't possibly think what could be the cause.

Many thanks in advanced,

Ed
 
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steadyeddie

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Mercedes CLK 320 W208
I should add that in two weeks time I'm driving down to Lake Como in Italy and would love the car to be in the best shape possible.
 

markmifsud

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I guess others might be able to help if you posted the codes? Did you get a copy of the original diagnostics?

I would assume that either your ODB reader isnt communicating with the car to clear the codes, or they are still current faults so will still show.
 
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steadyeddie

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Mar 7, 2011
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Mercedes CLK 320 W208
The original codes were:

P0150 O2 Sensor Upstream
P0306 Misfire Cylinder 6

Both O2 sensors also replaced.

It was on the second visit I was told about the possible blocked cat.
 
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PobodY

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CLK350 Sport
A misfire on one cylinder would certainly make the running uneven. - I assume it's definitely sparking on cylinder 6?

If you take the plug(s) out of that cylinder, what do they look like? - Hopefully like they should and not oily or sooty.

Can you get another lambda sensor (even a used one) to rule that out?
 

DSM10000

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Try changing the coil pack to one from another cylinder and see if the fault moves.
 

crisc204

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May 8, 2007
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Londinium
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w208 Coupe,
The Cat is outrageously dear from Mercedes even worse if you have a pre facelft w208 iirc so £1200 is not a totally outhere figure...

Follow advice from others as above
If they won't clear they are current/active faults

Its normally a failed or failing coilpack or worn/fouled plugs that cause this kind of thing.

When did it last have a set of Spark plugs?
 

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