Cls 55 amg misfire. Help

[Montana 55amg]

Hello, this is my last resort
Firstly a bit about the car
2005 cls 55 amg
88k miles
Upgrades
X pipe
Custom manifold
Ecu remap
Upgraded pulleys
So many cell sport cats

Problem
I've been experiencing a misfire, it comes on at low revs then if I stop and turn it off it goes back to normal. I used to get 2 weeks in between misfires now it's 20 mins.
The car feels like it loses all power and sounds horrible.
This week I have changed the Sparks, ignition coils and ignition leads, I've also cleaned the maf sensor.
I noticed both k&n filters were full of muck they are only 6 months old. When I disconnected the air box it seemed to run fine but this might be a coincidence,
I'm love the car and spent a fortune making it 600bhp but this is doing my nut in.
I've read threads on here about similar problems but everyone has a different solution.
Please this is my last hope to fix it.

Thanks in advance

 

[Montana 55amg]

Also it's a uk car only ever run on v power and fully serviced,

 

[Montana 55amg]

I know this is a community of like minded people but I'd be happy to donate some money to a charity of the users choice if I can get the answer,
Or take them out for a blap!!!

 

[jon_viola]

Have you tried changing the MAF sensors rather than just a clean? Sounds like a mixture problem and a sensor somewhere thats slowly drifting....

 

[m2287]

All I can say is to try a new maf sensor. Cleaning it might not have worked. Sorry I'm not of much help but it's a bit late so you won't get many replies, probably best to have a look in the morning!

 

[Montana 55amg]

Have you tried changing the MAF sensors rather than just a clean? Sounds like a mixture problem and a sensor somewhere thats slowly drifting....

No not yet, I'm happy to, would that be your part to change in my position?

 

[Montana 55amg]

All I can say is to try a new maf sensor. Cleaning it might not have worked. Sorry I'm not of much help but it's a bit late so you won't get many replies, probably best to have a look in the morning!

Thanks for the advice. I appreciate it. I know it's late for people to be on here

 

[Howard]

Over oiled K&N's have killed the MAS is my bet.

Have you put it on a STAR ? Swapping parts to find the fault is an expensive way of doing things.

Find a good Indy who can read the live data too , not just a back street garage with a generic code reader.

 

[Montana 55amg]

I have read posts saying either O2 sensor or crank sensor??

 

[Montana 55amg]

So maf sensor is the general consensus?? I was amazed how much muck was in the filters.

 

[jon_viola]

Yep I'd head that way. They are known for failing. Others with better knowledge of your particular car might be able to help further...

Good luck!

 

[Montana 55amg]

Is a maf sensor known as a air flow meter ?

 

[Montana 55amg]

Many thanks to each of you
Any other help or advice would be great

 

[Paddcomp]

I concur with the plugging in to a Star diagnostic, also check CO2 levels. You need an expert in front of the car with the right data, not on the other end of a screen.
Sounds an awesome car BTW.

 

[Fryingpan78]

Your car doesn't have a maf sensor, it's pressure (map) based.

Does it come on after it's been running a while or from cold?
What have you done to improve cooling with your mods?

It could be that the intake air temp is too hot. In this case the ecu will pull loads of timing out which will make the car feel lazy and sound like a boat. With your other mods perhaps this effect is amplified.

Do a search on here for intercooler (IC) pump and see if the report issues sound familiar. A common problem with these engines is the weak pump and any mods will excacerbate this.

-t

 

[Montana 55amg]

IC pump wise I had the problem of the supercharger getting hot and turning off and I've had a uprated Ic pump and it's been perfect since then.

It made no difference weather the car was hot or cold. Just as low revs the misfire would just happen.

I was getting excited thinking maf sensor however you don't think I've got one ?? I definitely cleaned something under the air boxes ??

 

[Montana 55amg]

Update!!!

Starr says misfire on cylinder 8
Which is cylinder 8 , and any suggestions? I've had uprated fuel injectors.

 

[DSB SL AMG]

post error

 

[ChrisA]

It could be the injector for Cylinder 8
You need to get the car plugged in to STAR diagnostics otherwise you will be just guessing

What are your IAT's at idling?

 

[DRBC43AMG]

Update!!!

Starr says misfire on cylinder 8
Which is cylinder 8 , and any suggestions? I've had uprated fuel injectors.

Cylinder 8 is the one at the rear of the right hand bank when facing the engine.