sambam2006

Hi guys,

I purchased a CLS 63 2011 last Thursday and just yesterday the car began to misfire on the motorway and the engine light came on, the car was hesitating on idle and juddering. At some occasions the engine management light was flashing.

Managed to get it to a local specialist who I know and they plugged it in and got the following codes:

P0307 - Cylinder 7 Misfire
P0305 - Cylinder 5 Misfire
P0306 - Cylinder 6 Misfire
P0308 - Cylinder 8 Misfire

They cleared the codes and the above were intermittent codes stored.

So If I am right half the engine is working with 4 cylinders down.

I spoke to the person I bought the car off as it was a private sale and they said without surprise that they didn't know what was going on.

Any advice you guys can give? (Car is out of warranty)

LaunchPad

Sounds like bad spark plugs I would try find out how many miles they have on them

sambam2006

We replaced the 4 coils with the coil packs and the 4 spark plugs on the bank that was showing the errors. Still same problem but its showing

cylinder misfire at 6 and 7 only.

could it be an injector?

sambam2006

I managed to take a video in detail:
Any suggestions would be much appreciated thank you

compaddict

iTrader: (1)

The PO of my car had a CEL for a misfire and while under CPO MB did a flash of the ECU last January. Same year, same engine.
No issues since.
Vince

6speeddave

I would go ahead and suggest that it may be due to a fault 02 sensor on that side? If all 4 cylinders misfire at once there is no way that all 4 coil packs or 4 spark plugs failed at the same time. I highly doubt its one fault injector either. Regardless, one component that controls that entire side of the engine is probably to blame. Do you have downpipes or an ECU Tune on the car? It sounds loud in the video.

sambam2006

Interesting you say that I was talking to the technician regarding this, I told him to update the firmware back to standard Mercedes firmware but his star diagnostic is an ali express version lol. So it's something I will do after friday if the new injectors dont fix the issue, they will arrive tomorrow, fingers crossed.


Hmm I initially thought that at the start but the technicians don't think that, but I guess I will find out tomorrow as my injectors arrive through the post so fingers crossed that is the issue so I can have my car back and enjoy it.

The previous owner got an ECU remap and exhaust mod, But I don't know anything more than that. I will looking to get the remap taken off and back with the original Mercedes firmware if the injectors doesn't fix the problem.

sambam2006

UPDATE: It was difficult finding a Mercedes Specialist that had Star Diagnosis (Online), but finally took it to AutoClass in Milton Keynes here in the UK and they tried to update the ECU but it already had the latest software so they did SCN coding to it and reset all values.

Problem solved, no more misfire or CEL, car is running like nothing happened.

compaddict

iTrader: (1)

Thanks for the update!

Jan AMG

Mikeki7

I wonder what would cause the ECU to freak out and store incorrect information in the first place. Was the ecu connector clean? no oil on the ecu pins?

sambam2006

I thought the issue was fixed but the ECU reset which they performed using Star is only a temporary fix until the car relearns and then the problem comes back, car would run fine for 4 days after ECU reset and the CEL lights gradually reappears and the car begins to stutter and hesitate during IDLE.

Still getting Random Engine Misfire, so took it to Mercedes and they did the following:

Check Fuel Pressures and Internal Leak tightness = Pass
Check Camshaft Solenoid = Pass
Manual Compression test (Spark Plugs removed) = Pass
Injectors swapped in different banks, tested and re installed = Pass
Electrical System Check = Pass
8 Coil Packs changed
8 Spark Plugs Changed
Service A carried out (incl Air Filters)

So at this present moment they have changed the Lambda probe on the affected misfire bank (Left Side)
And they reset the ECU again and will see what happens now, car is running fine at the moment, hope it fixes the issue this time if not then someone please shoot me, already spent over $2000!! :-(

KLR CLS

Miss fire on a whole bank would be o2 sensors or harness related. Hopefully the sensors fix it

ecmexchange

Heres hoping that's that. Starting to get expensive!

sambam2006

After over a week of running the car I think the problem has now finally gone away, it was the o2 Lambda sensor which was causing the flashing CEL and misfire. These were checked at the start of the diagnosis and there was no indication it was faulty but it was in a bad shape apparently when removed said Mercedes. Glad it's finally over

compaddict

iTrader: (1)

Thanks for the data!