W202 C200: Hesitating and misfiring engine

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Changes to instructions SORRY got this back to front. First here's a picture of the parts involved. The coil extender [part 83]you want to change is the one under coil on cylinder 4 the plug lead to change [in its entirety!] is the one from that coil to the plug on cylinder no 1--- then the other extender under the coil on cylinder 2 and the lead to plug 3. hope this is clearer.
 
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Changes to instructions SORRY got this back to front. First here's a picture of the parts involved. The coil extender [part 83]you want to change is the one under coil on cylinder 4 the plug lead to change [in its entirety!] is the one from that coil to the plug on cylinder no 1--- then the other extender under the coil on cylinder 2 and the lead to plug 3. hope this is clearer.

Okay that is much clearer, thanks! Is the coil extender a different part by itself? In my case it is stuck pretty tight to the coil. I examined it when I took the ignition coils out and there is a small crack at the bottom side (~3-4mm in length). Other than that it is not degenerated in any way. Is this is a part that I can get only from the dealer or I should be able to get it at the Bosch delership as well?:confused:

I think I made a mistake in the numbernig with the cylenders. From your picture it seems that, my car worked fine without the firing of cylinder number 4 and not 1 as I mentioned earlier!:wallbash: I was confused about the numbering. So coil 1 (near firewall) is on cylinder 1 and the coil 2 is on cylinder 3!

Am I still looking at the coil extender issue? Really sorry about the mistake!!:doh:

What I did was remove the HT cable from the spark plug on cylinder 4 and start the engine and it fired alright, not perfectly alright but much better then how it sounds wih all 4 cylinders plugged in. Should a 4 cylinder car sound fine only with 3 cylinders firing? Sorry for the noob question! :eek:

Thanks a lot for your time!
 
Sorry if this confuses you but the convention is to number the cylinders from the front. So the one nearest the bulkhead is no 4 the one nearest the radiator is no1 . Remember because the coil is attached to 2 plugs any fault on either plug lead or extender may effect firing of either cylinder. The extenders are a separate item as shown in the diagram. should just plug into the coil afaik. Best to get them from your MB dealer- they are less than £10 each-- if you give them your chassis no that should get you the correct part.

P.s. if you run the car in the dark with the cam cover plate removed you may see any HT flash over- but if the problem is in the extender or plug lead internally this won't show up of course.
 
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Sorry if this confuses you but the convention is to number the cylinders from the front. So the one nearest the bulkhead is no 4 the one nearest the radiator is no1 . Remember because the coil is attached to 2 plugs any fault on either plug lead or extender may effect firing of either cylinder. The extenders are a separate item as shown in the diagram. should just plug into the coil afaik. Best to get them from your MB dealer- they are less than £10 each-- if you give them your chassis no that should get you the correct part.

P.s. if you run the car in the dark with the cam cover plate removed you may see any HT flash over- but if the problem is in the extender or plug lead internally this won't show up of course.

Oh okay, so after cylinder no. 1 that after disconnecting made everytihng seem okay.:thumb:

I am getting the extender tomorrow from the dealer and try to replace booth of them to see if it makes any difference.

If the HT leads are actually two different wires then I think they are fine, because I switched them around between1,2 and 3,4 and it did not seem to make any difference i.e. cylinder 1 still seemed to be the problem cylinder.:wallbash:

Would be able to comment on what are the chances that this might be a seal ring/ valve issue? I don't seem to be loosing any oil or giving out any coloured smoke. Oil level, coolant level are all good. No check engine light coming on either.:dk: I am really not looking forward to any major head replacement/ overhaul work!:wallbash:
 
Take it one step at a time. Get the extenders and give the fouled no 1 plug a bit of a clean up or use the best looking one of the four old ones. The most likely major incident scenario is a failed cylinder head gasket-- The early 4 cylinder engines had a reputation for cylinder head bolt stretch problem but not by your engine date. One check you can do is to take out the spark plug and shine a torch down the hole You should see the top of the piston is a nice brown or slightly black colour. If however it looks " oily black"= wet then its possible the CHG has gone or head has cracked. Its best to do this on a "good" cylinder and a suspect one to get the contrast in appearance. ---but one thing at a time remember- try the plug leads/extenders first.
 
Take it one step at a time. Get the extenders and give the fouled no 1 plug a bit of a clean up or use the best looking one of the four old ones. The most likely major incident scenario is a failed cylinder head gasket-- The early 4 cylinder engines had a reputation for cylinder head bolt stretch problem but not by your engine date. One check you can do is to take out the spark plug and shine a torch down the hole You should see the top of the piston is a nice brown or slightly black colour. If however it looks " oily black"= wet then its possible the CHG has gone or head has cracked. Its best to do this on a "good" cylinder and a suspect one to get the contrast in appearance. ---but one thing at a time remember- try the plug leads/extenders first.

Hello thanks for the reply.

I managed to diagnose the problem to one of the ingnition coils firing onlythrough one outlet. So one of the HT leads is not getting any voltage. I got the workshop to confirm it on STAR and they seem to think the same.:bannana:

Now the issue of replacement, I could replace it myself and I had already taken them out while changing the spark plugs. :rock:

Does any one know anywhere online where I could get them for cheap? I am looking for Bosch parts. I managed to find an European wrbsite which seld them for pretty cheap even postage. I asked the price here and it is approximately $400 for one! :wallbash:
 
Try MB agents. Here in South Africa they are around 40 pounds so I know over there it will be a lot cheaper to buy. It is a Bosch unit so you should be able to order from them as well. Hope this helps.
 
Try MB agents. Here in South Africa they are around 40 pounds so I know over there it will be a lot cheaper to buy. It is a Bosch unit so you should be able to order from them as well. Hope this helps.

I tried to contact the MB agents here, but none of them sell of for less than ~300! I saw them online for $90! :wallbash:


That is a really good DIY!
The DIY I used here did not mention that I would need a really long extentions to reach the spark plugs. I opened up the cover, removed everything and thought how big an idiot I was to think that I could get them off without a spark plug ratchet! :wallbash: So it was back to the store for me, to buy a ratchet!

INCHCAPE are a big online supplier of genuine MB parts in the UK. I don't know if they supply overseas?? I suggest you send them an email enquiry asking about price and carriage. About Us - Mercedes-Benz Parts, Inchcape

this form

Contact Us - Mercedes-Benz Parts, Inchcape

I have sent them a mail. Now waiting for the reply. I managed to find an ignition coil for $50. It is used. I think it is coming from a car involved in an accident of some sort. Is there anyway to test them very well before buying? It works, that I am sure of, because the car it is coming off starts and sounds good.:dk:

Should I go for it? I can get them online, both of them for $90 along with $50 shipping to here. I think it is called Auto Parts | Car Parts, Truck Parts & Car Care Online Shop - seekpart24.com. I want my car on the road as soon as possible. Kind of painful not having the car right now. I am thinking of getting this used one for now, and get the new one's from seekpart at leisure. Even if this used one fails, which it will eventually :D, I'll just put the new on in.

Will be fitting it in this afternoon. Will post in the evening as to how it went. Changing the coil extender as well. Mine is stuck pretty tight, might break when I try to pull it off! :doh:
 
Sound's a plan -secondhand parts are always a bit of a lottery- you pays your money and you takes your chances. Can't comment on the German website-- never used em. Appears to be a genuine Trusted Shops scheme website--- clicking on the logo appears to link to a secure website. Sometimes folks stick logos like this on their website to give the "appearance" of respectability but usually any link doesn't work
 
Sound's a plan -secondhand parts are always a bit of a lottery- you pays your money and you takes your chances. Can't comment on the German website-- never used em. Appears to be a genuine Trusted Shops scheme website--- clicking on the logo appears to link to a secure website. Sometimes folks stick logos like this on their website to give the "appearance" of respectability but usually any link doesn't work

Hello! I changed the ignition coil and the coil extender yesterday. It was the coil near the firewall that was firing only to cylinder 4.

Managed to get the coil and the extender for $50!:bannana: Coil is Bosch and extender is Beru. Quite happy with it till now. Runs really well. I had changed the spark plugs a few days back and now that the car is running, I feel that it has become much more eager. It seems much more eager to "lean" ahead in D. While onthe topic, does this car have an electronic throttle cut-off? Does it automatically switch off the throttle if the brakes are depressed? I don't feel it has, not sure if it was ever meant to.:dk:

I am going to order a HT setup from the German website in a few weeks. Planning to get two ignition coils, two extenders and the HT cable set and change everything, just for peace of mind. :)

The only casulty of the entire installation was the poor allen head screw on the cover. I think I am the only person in the world who has managed to break a screw using a torque wrench!:wallbash: Feel sos tupid! But nevertheless it is broken in a way that the top bit has come off, so the cover is still removable. The cover is snug with 2 screws and not rattling. Have to get that screw drilled out soon, don't want water seeping through! :eek:

Thanks a lot to everyone on this forum for helping out!!!! :bannana:
 
Glad it's fixed!

I had a damaged extender thingie on my old c230k and it took about 2 years of messing about with different workshops until it was sorted.
 
My only comment would be - why spend more money now the problem is fixed. If you were buying all new components fine- but surely the parts on the German site are second hand and might be older than the ones you have on the car at present? The time these components come under strain is when you change the plugs- the moral of the story is to handle them all gently and avoid bending the wiring leads as much as possible. I can understand why you want to do this after your recent problems but maybe an idea to keep the money for now to use when something else goes wrong? Glad the car is sorted.:thumb:
 
Glad it's fixed!

I had a damaged extender thingie on my old c230k and it took about 2 years of messing about with different workshops until it was sorted.

Hi Shude. It is a relief that it is sorted. I was worried about somthing going wrong with the seal rings. Glad it was just the coils. I read about the modes you have done on your W202, especially the COMAND. It looks amazing! :thumb:I can't afford it at the moment!:(
I am thinking of getting puddle lights for my W202 as well. It has the plastic cover instead of the bulb right now. I don't understand, mine is Elegance complete with sun-roof, burr-walbnut, why did the first owner not tick puddle lamps!:wallbash: Might get an automatic dimming rear view mirror while I am at it! :D

My only comment would be - why spend more money now the problem is fixed. If you were buying all new components fine- but surely the parts on the German site are second hand and might be older than the ones you have on the car at present? The time these components come under strain is when you change the plugs- the moral of the story is to handle them all gently and avoid bending the wiring leads as much as possible. I can understand why you want to do this after your recent problems but maybe an idea to keep the money for now to use when something else goes wrong? Glad the car is sorted.:thumb:

Hi Grober. What you are saying is true. I am scared of this new part failing and leaving me stranded. It did not have any mechanical damage, looks like new. :dk:
I think I will save my money and buy it when it fails!
Thanks!:)

OT: I have had this car for 2 years and nothing has ever gone wrong with it! It has done 240,000 Km and not a single creak! :rock:
 
Hi,very similar fault on my 2000 c200,it was fuel injector.
 

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