C32 random engine misfire

[John_Doe]

Afternoon all,

I have had this random engine misfire for a while now and it's been too several indy garages and even main dealer. All they tell me is that it's misfiring on cylinders 1 and 6. They recommend changing plugs, leads and coil pack. I can get the same bloody info off a silly little OBD 2 reader!

The car will run fine for a while and then it will kick up the engine light and go into limp mode. So reset the system and it goes away.

Anyway I thought I would start by fitting new plugs to cylinder 1, and swapping leads and coil pack between 1 and 4. Obviously had to be 1 and 4 because the leads are different for each cylinder but either side match. I ran the car and the same thing happens again. Still on cylinder 1 and 6. So that tells me it's not plugs, leads or coil.

Where do I go next considering garages are really not helpful with this.

I should also note that I am losing coolant :-(. I started thinking head gasket but I do not have any other signs of HG failure. It doesn't over heat, no cream in oil and if it failed between cylinders surely it would be between cylinders that are side by side, not at different corners. The coolant leak appears to be leaking onto the floor while parked and not being drank by the engine, however it does smell a little exhaust / oily

Oh and! If I put my heater on with the windows up I will pass out from the smell of burning oil/ fuel / exhaust fumes! Any idea what that is about. Why would I get an exhaust smell through my air vents?

 

[xavier]

Hi John,
Have similar issues as you on my C55.
It started with misfiring and limp mode. Garage has changed all spark plugs, HT leads and MAF sensor (as per faults on the system). All done using genuine MB parts etc. Everything was fine but once a while when on longer journey at slow constant speeds (50-60) my engine light is flashing (???) and then staying on for a day or two.
I could clearly hear engine misfiring on one occasion but once you turn engine off/on everything goes back to normal. It went back to my specialist garage for checkups and they cannot find anything and despite managing to get engine light on, still nothing is on a system. I must say that they supposed to be reputable garage, specializing in MB, BMW & Porsche with correct equipment so should know what they are doing (???).
I also get after warming up engine this smell of burning oil when heater is on.

Im giving up and really don't know what to do and think now.
Sorry to steal your thread but it seems like I have similar issues.
BTW Im not losing any coolant.

 

[Neil Mackay]

Afternoon all, I have had this random engine misfire for a while now and it's been too several indy garages and even main dealer. All they tell me is that it's misfiring on cylinders 1 and 6. They recommend changing plugs, leads and coil pack. I can get the same bloody info off a silly little OBD 2 reader! The car will run fine for a while and then it will kick up the engine light and go into limp mode. So reset the system and it goes away. Anyway I thought I would start by fitting new plugs to cylinder 1, and swapping leads and coil pack between 1 and 4. Obviously had to be 1 and 4 because the leads are different for each cylinder but either side match. I ran the car and the same thing happens again. Still on cylinder 1 and 6. So that tells me it's not plugs, leads or coil. Where do I go next considering garages are really not helpful with this. I should also note that I am losing coolant :-(. I started thinking head gasket but I do not have any other signs of HG failure. It doesn't over heat, no cream in oil and if it failed between cylinders surely it would be between cylinders that are side by side, not at different corners. The coolant leak appears to be leaking onto the floor while parked and not being drank by the engine, however it does smell a little exhaust / oily Oh and! If I put my heater on with the windows up I will pass out from the smell of burning oil/ fuel / exhaust fumes! Any idea what that is about. Why would I get an exhaust smell through my air vents?

Where does the coolant appear to be leaking from!? Front or rear of the engine bay!?

 

[John_Doe]

Hi John, Have similar issues as you on my C55. It started with misfiring and limp mode. Garage has changed all spark plugs, HT leads and MAF sensor (as per faults on the system). All done using genuine MB parts etc. Everything was fine but once a while when on longer journey at slow constant speeds (50-60) my engine light is flashing (???) and then staying on for a day or two. I could clearly hear engine misfiring on one occasion but once you turn engine off/on everything goes back to normal. It went back to my specialist garage for checkups and they cannot find anything and despite managing to get engine light on, still nothing is on a system. I must say that they supposed to be reputable garage, specializing in MB, BMW & Porsche with correct equipment so should know what they are doing (???). I also get after warming up engine this smell of burning oil when heater is on. Im giving up and really don't know what to do and think now. Sorry to steal your thread but it seems like I have similar issues. BTW Im not losing any coolant.

I know how you feel. I read the codes myself and went into Mercedes main dealer and told them I am misfiring on cylinders one and six, can you investigate and possibly tell me why. They charged me £140 and came back and said that I am misfiring on cylinders one and six! I said I know but why. Got told basically to think about a new car because he can only suggest changing plugs, leads and coils and the cool packs are £85 each and leads are about £25 but no guarantee this will solve any thing. I feel really ripped off and a complete lack of customer service. But never mind what's done is done, I just won't be taking it back again any time soon regarding this issue

 

[John_Doe]

I don't honestly know, it doesn't leak all the time. I have the same as Xavier, it will do it more after a long journey. I would say more towards the front of the engine, drivers side. Almost as if the coolant tank is getting hot and expanding. I need to lay a sheet of cardboard down underneath after driving for a while and see where she is dripping from.

After the reset I managed to get about 60miles of driving before this happened, so I may just take a cruise around tonight until this happens and lay the cardboard down overnight

 

[Neil Mackay]

I don't honestly know, it doesn't leak all the time. I have the same as Xavier, it will do it more after a long journey. I would say more towards the front of the engine, drivers side. Almost as if the coolant tank is getting hot and expanding. I need to lay a sheet of cardboard down underneath after driving for a while and see where she is dripping from. After the reset I managed to get about 60miles of driving before this happened, so I may just take a cruise around tonight until this happens and lay the cardboard down overnight

Charge cooler pump is just behind the spot light on that side........!

 

[John_Doe]

The Johnson CM30 was my next purchase after fixing this misfire issue

 

[Neil Mackay]

The Johnson CM30 was my next purchase after fixing this misfire issue

Don't suppose you want a 65mm pulley and sl55 intakes as well do you.......!?

 

[John_Doe]

Don't suppose you want a 65mm pulley and sl55 intakes as well do you.......!?

Interested. How much? Why ain't you fitting them?

 

[Neil Mackay]

Interested. How much? Why ain't you fitting them?

Selling the car so putting to standard again!!! To really benefit you'd have to get the engine mapped for the pulley and intakes....via Eurocharged! Retail on the intakes is £350 and £499 on the pulley! Mines done about 10-15k (trouble free) and I have a spare bearing for the pulley aswell.....pm me an offer of your interested and ill see what delivery would cost if agreeable!!!

 

[John_Doe]

Ok so it looks like the coolant leak is coming from the back of the engine. what does that mean?

 

[Neil Mackay]

Ok so it looks like the coolant leak is coming from the back of the engine. what does that mean?

Have you had it up in a lift!? There one hose at the rear into the heater matrix I think!? Heater matrix maybe!? Is there any dampness I. The passenger footwell!?

 

[John_Doe]

No I haven't had it up in the air yet. I always thought it was coming from the front tank / pump area.

I do get s big build up of condensation and I have put one of those dehumidifiers in the car to draw it all out. I haven't noticed any in the passenger footwell yet. Where abouts is the hose? Can I see it from the top or only under the car?

 

[Neil Mackay]

Right at the back under all the vacuum pipes so you can't really see where it comes out of the block really I'm afraid!! Sounds like it needs to go on a lift or take the bottom plastic tray off to see if it shows the exact location of any dripping!!

 

[Neil Mackay]

Ok so it looks like the coolant leak is coming from the back of the engine. what does that mean?

It's definitely coolant leak and not the condensed water dripping from the a/c!? That drips just in front of the gearbox oil sump.....coolant would feel slightly oily between you fingers and be bluey/green..........

 

[Bellow]

.coolant would feel slightly oily between you fingers and be bluey/green..........

....and taste sweet on the tip of your tongue.

 

[John_Doe]

Definitely coolant. Plus I have to keep filling it up. So she is probs more water than coolant now lol.

Went to the garage today for a sniff test and it's not head gasket. They reset and cleared all faults. Apparently the plugs on cylinder 1 were the wrong way round. Doh, that was me switching leads. So they put it right again but this afternoon when the light came on, it's still cylinder 1 and 6.

I really am at a loss! The garage said the next thing they could do is a smoke test. Something to do with a cone and pumping smoke into the engine to check for air leaks / holes in breather pipes?

 

[Neil Mackay]

Definitely coolant. Plus I have to keep filling it up. So she is probs more water than coolant now lol. Went to the garage today for a sniff test and it's not head gasket. They reset and cleared all faults. Apparently the plugs on cylinder 1 were the wrong way round. Doh, that was me switching leads. So they put it right again but this afternoon when the light came on, it's still cylinder 1 and 6. I really am at a loss! The garage said the next thing they could do is a smoke test. Something to do with a cone and pumping smoke into the engine to check for air leaks / holes in breather pipes?

I hate to say it but I've been through all this!! Mine ended up being an external head gasket leak which passed all the standard pressure tests, sniff tests, oil contamination test, and cylinder compression tests........ Mine didn't even have any overheat or misfires or any indication. It had leaked all over the starter motor, exhaust etc which when I added UV dye to the coolant turned the bottom of the car into Blackpool illuminations!!!!

 

[John_Doe]

Uv dye sounds like the next step for me then. I need to modify my car ramps to get it fully in the air

 

[Neil Mackay]

Uv dye sounds like the next step for me then. I need to modify my car ramps to get it fully in the air

Have you had any luck tracing the leak yet!?