Misfire

[Ledbelly]

Hi all,
I have a 2002 E240 W210 with 65000 miles on it and it has a misfire problem.
It runs really smoothly but has a slightly lumpy idle.
If I floor the throttle I get the check engine light and it throws a misfire code for either random multiple misfires, cylinder 3 or cylinder 5.
Once I get the CEL it does run on 5 cylinders but if I switch off and start back up it is fine.
I have cleaned the MAF sensor and tried changing coils ( I have some spares) but it makes no difference.
Any ideas out there?

 

[Bellow]

Unless it is fuel starved, misfires on opening the throttle (though 'flooring it' is demanding of the fuel system - what's it like when the throttle is opened more slowly?) are usually ignition related.
Are all the engine related earths in good condition?

 

[pcthrillrider]

have you changed the plugs? maybe dodgy leads

 

[Bellow]

Maybe worth having a look with the bonnet up in darkness and looking for stray sparks from the HT side. And the typical 'click' noise the tracking creates.

 

[grober]

M112 Rough Idle When Cold - Fixed - MBWorld.org Forums
With the M112 it would appear its often the coil to plug leads rather than the coils themselves?

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