S65 AMG misfires (not the usual)

[LostKiwi]

Single fuel rail with single supply

Which bank is fed first from the pump?

 

[alexanderfoti]

Which bank is fed first from the pump?

Its fed in the middle:

 

[Equium Duo]

I'm new and have no experience with your V12, I had a V6 GTO twin turbo and had a weird misfire that I found was consistent to only a single bank of cylinders. (The spark plugs showed us which one had the misfire) Did exactly as you all have suggested, new plugs, compression tested, injectors swapped, new injectors the whole lot. Even replaced the hydraulic lifters and tried someone else's ECU and cam sensor.

In the end it got really bad to the point where I felt like I was just causing damage (no evidence but a gut feeling). We had a look at everything we had done and found that the hydraulic belt tensioner for the cam belt was faulty and *possibly related* (we never knew for sure) one of the idlers had a stiff spot when rotating. There was a slight squeek when cold starting but nothing dramatic. So we guessed that the misfire was caused by that idler. We replaced both and we were good.

Caveat: I never did the experimenting to figure out where the stiffness was effecting in the ignition cycle or whatever. So never had a rock solid "root cause."

Long shot but you seem to have done a lot and wanted to contribute.

 

[alexanderfoti]

Thanks all.

Injectors are off being flow tested and spray tested.

Eurocharged finally came back to me and said .... its the coils. AHAHAHAHAHHAHA

What a waste of time. I said to him, I am not buying a 4th set of coils just to prove you wrong.

He said put the car back to standard and test it again, so now I am doing that.

 

[alexanderfoti]

Injectors replaced. Cold start rough idle gone but misfires still there. grr

Edit: Cold start rough idle on 10 still there, goes after 1 minute. There is obviously a top end problem on that cylinder, probably a leaking valve.

 

[peterws1957]

Injectors replaced. Cold start rough idle gone but misfires still there. grr

Blimey af I dread to think what all this would have cost if you had dropped it off at your local MB dealer and just said "fix it".

 

[alexanderfoti]

Blimey af I dread to think what all this would have cost if you had dropped it off at your local MB dealer and just said "fix it".

Im sure they would have said "new engine required", and when fitted, given it back still broken!

 

[bembo449]

So are you going to remove and inspect that head?

 

[alexanderfoti]

So are you going to remove and inspect that head?

No chance.

Its going to MSL on Friday/Monday for some testing on the dyno/tweaks to the map. If they can't sort it, then ill put it back to standard.

Ill put the stock ECU map on it and call it a day. Its only misfired since the eurocharged map went on it. Lots of people run the map with good results but Jerry is a real ***** when it comes to customer service when the customer has issues.

 

[Wighty]

You have certainly put some hours in on this car , fingers crossed it gets sorted .

 

[alexanderfoti]

You have certainly put some hours in on this car , fingers crossed it gets sorted .

Tell me about it. Even I have to draw the line somwhere!

 

[Wighty]

Tell me about it. Even I have to draw the line somwhere!

My line was 100 hours ago , but then again i'm a mere beginner

 

[bembo449]

No chance.

Its going to MSL on Friday/Monday for some testing on the dyno/tweaks to the map. If they can't sort it, then ill put it back to standard.

Ill put the stock ECU map on it and call it a day. Its only misfired since the eurocharged map went on it. Lots of people run the map with good results but Jerry is a real ***** when it comes to customer service when the customer has issues.

oh , I didn't realise the issue had only come about after a remap ? that surely can only mean its a bad map , right ?

 

[alexanderfoti]

oh , I didn't realise the issue had only come about after a remap ? that surely can only mean its a bad map , right ?

"Oh no, cannot be a bad map, its definitely a hardware fault with the car" bla bla bla.

Working with tuners is trying at the best of times.

Its a "box" tune, so they develop the map on one car, then turn it down 5% then apply that same map to other cars. Their response when you say its the map, is "this map works fine on 95% of cars so it must be your car".

I believe that something on my car is just slightly out of spec (possibly fuel pressure as that is the only thing I haven't tested), but without the support from the tuners, its just me guessing.

Luckily MSL feels my pain and is helping me, as he supplied the map from EC in the first place. It needs some time on the dyno, some data logging and some map tweaks in my opinion. If they can't sort it, ill just do an Xentry ECU update and put it back to standard.

Additionally, a local place did a remap to it a year or so ago, and it made no difference to the car. When they map the car, they pull the ecu map off the car, modify the locations they know about to change the desired characteristics, and then put it back. I am wondering if the original map modified something that they did not know to look for.

Anyway, hopefully we have some movement this week/next week.

It is nice to have it back on the road though.

 

[bembo449]

maybe it was already mapped ? unless you've had it from new ?

 

[alexanderfoti]

maybe it was already mapped ? unless you've had it from new ?

Apparently was stock. My before (first) remap dyno numbers matched with stock numbers.

 

[bembo449]

very odd , im 20 plus cars remapped now and not one hasn't felt much improved for it , especially the turbo cars , usually night and day different , is it possible they told a porky and took your cash all the same ??

 

[alexanderfoti]

very odd , im 20 plus cars remapped now and not one hasn't felt much improved for it , especially the turbo cars , usually night and day different , is it possible they told a porky and took your cash all the same ??

I agree.

Who the first lot or MSL/Eurocharged?

 

[bembo449]

whoever carried the first remap

 

[alexanderfoti]

whoever carried the first remap

Quite possibly, although I did watch the mapping process, and got quite involved with the contents of the map when things didn't work properly, as I have done some mapping myself in the past.

Im pretty sure they just didn't know what they where doing. In the map there may be 5 or 6 different ignition maps, for example.

One may be for different coding types, different ambient temperatures etc. You don't know which one the car uses, so tuners use definitions bought from other places to find out which bit in the map file they should be modifying.

If they use poor definitions or don't really know the platform well, then the changes may well do nothing.