Misfiring of Cylinder 4

[Hi-Ho Silver]

Hi all,

I had a warning light appear on Sunday. Took it MB Hove this morning, who ran a computerised diagnosis to find and clear the fault.

Small 'f' type fault. P201B-004 'Misfiring of cylinder 4' Status 'Stored'.

I had new plugs fitted two weeks ago during an A service. The MB tech has cancelled the fault and advised me to keep an eye on it. in my day, I could see the distributor cap and HT leads and I could change them anyway but this lump is impregnable to my eyes and I can't see much of anything.

Any ideas or questions which would help me to understand a bit more about this? Any suggestions?

Ta,

Silver H.H

 

[shorty]

The miss fire could be due to inlet valve ,its been known to happen with the M271 engine .
I was talking with my local MB specialest today and he was telling me about an E200 k that he is working on , this car had a misfire on cylinder 1 , all the inlet valves where changed along with the inlet and exhaust valve springs . This didnt solve the missfire , it was then suggested by MB that the car needed my injectors and ECU .
When the indy removed the cylinder 1 injector he discovered traces of water with the petrol !
The tank has been drained , this seemsa to have cured the missfire ,
could ne worth checking you car for water in the petrol

 

[Hi-Ho Silver]

Water in the petrol is something I hadn't thought of. IS there any way I can deal with this myself? For example, by running the car until it limps onto my nearest forecourt and the filling up?

Would using 97 RON premium unleaded instead of 95 RON unleaded make any difference?

What about mixing the two in the same tank?

Chairs,

Hi-Ho

 

[Bellow]

Hi all,

I had a warning light appear on Sunday.
I had new plugs fitted two weeks ago during an A service.

Coincidence???

 

[Hi-Ho Silver]

I take your point Bellow but it was 'slightly misfiring' before the service. It didn't get any better or worse until Sunday, when I started it first thing and it really misfired but that cleared after a few seconds and hasn't happened since.

 

[Bellow]

You can see why I thought that though!
If you are certain the misfire is cylinder specific, you can rule out a lot of general potential causes that would affect all cylinders. Should speed up the diagnosis a bit.

 

[Hi-Ho Silver]

Yup I can see why you thought that. Plugs n points used to be those things one could easily see and deal with but alas no more.

I'm still not sure what the cause of the misfire on cyl4 is... I still want to douse everything in WD40, as that used to work perfectly well when cars had engines you could see eg Morris Traveller.

On another thread, some folk are swearing by Iridium plugs over standard MB ones. No idea but if it helps, i'll change them. I'd also like to change the HT leads but I can't find the buggers anywhere! Where are my points? You know, the easy to deal with things which I used to unclip, spray with moisture repellant and hey presto?!

I'll get to the bottom of it because i'm probably burning too much fuel as a result.

 

[Bellow]

Or not burning the fuel - which is worse as it will then burn in the cat which will overheat it.
First thing I would do if I was you is have a peek under the bonnet with the engine running at night, in darkness. Any high voltage leaking should be visible as arcing. It wont be obvious if any arcing is occurring at the plug on account of the deep well but tracking marks may remain.
After that the fueling is the suspect. Weak through dirty injector or air leak, or rich through dribbling injector. Do you have the plugs that came out 2 weeks ago? They may provide a clue.

 

[Hi-Ho Silver]

Are the plugs and leads underneath the red lid on the engine which has 'Kompressor' on it?

I don't have the old plugs as MB replaced them and have probably binned them by now. I'd like to think that the tech would have spotted and reported any issues with the plugs had there been any.

I thought about the injectors. Would something like that show up during a diagnostic check or is that something which needs to be looked into?

Thanks for your advice.

 

[grober]

If you look at the first picture on this thread http://www.mbclub.co.uk/forums/engi...k-rough-idle-detonations-exhaust-headers.html you will see a picture of the cylinder head cover with the red kompressor plate removed. inside there are 2 black square objects -these are the high voltage coils which supply 2 spark plugs one directly underneath the coil and the other under the orange/red connector. The plugs are hidden deep in the head so there are long connectors to extend the leads down to them-- these often go faulty causing misfiring. The coils or their low voltage supplies [insulation fails] can also fail due to heat[ enclosed space too close to the engine] This sometimes happens after the wiring or connectors/extenders are disturbed --during a plug change for example!!! Don't ignore it as misfiring like this can lead to engine ECU failure= expensive. Don't blame the MB tech for the failure --it happens on these cars with age unfortunately,but they really should have picked up on this fault during the service
These 111 engines are all sightly different wrt ignition layout but but this will give you the idea http://mb.neoriginal.ru/part/class/...imgno/2/retcat/45Y/rettype/208/retsubtype/347

 

[Bellow]

I thought about the injectors. Would something like that show up during a diagnostic check or is that something which needs to be looked into?

As a misfire?

To this point I have been treating this as if it was any engine. Good to see Grober coming in with more specific information, and possibly more to follow re fueling if the ignition side checks out.
Depending on how bad the misfire is, it is sometimes worth trying to move it to another cylinder to identify a faulty component, eg injectors. If you swapped #4 and say #1 and #1 cylinder started misfiring and #4 behaved, it would point to the injector being at fault.
Will only work if you can identify which cylinder is misfiring and the only simple way I know of is feeling the heat in the branches of the exhaust manifold with them all at a low enough temp not to burn you. Infra red temp gauge would help here, but do not be tempted to pull plug leads with the engine running to trace the fault. Or all the ignition system will be liable to fail.

 

[Hi-Ho Silver]

Thanks guys.

A ha! So that's what's under that red plate. None of this looks like i'll be able to do anything about any of it myself, so i'm going to find a good indie in the Brighton area. Three have been recommended to me by fellow forum members; John Haynes, A J Robertson and Around the Benz and i'll be calling all three tomorrow to get some idea of what I can do about it and by whom. Up until this car, i've always had cars which I could do basic stuff on myself but this is way beyond my Sunday morning kerbside activities.

The fault on the 'initial quick test log' actually reads "P201B-004 Misfiring of cylinder 4, damages TWC (P0304)"