Misfire - Under hard acceleration

[cl55 amg]

My money is on the HT side of things also. You will hardly notice a slight misfire on a big V8 until you put the foot down. A quick test for the Maff is to disconnect it altogether-the ECU will default to backup settings but should still drive reasonably well.

I have heard of removing the maf before, if I was to do this would I then be able to drive the car?

 

[cl55 amg]

Question:

Does the misfire occur at full load e.g full throttle at 2500rpm, or at high revs, but low load e.g 5000rpm at part throttle.

Typically a fault from a weak spark, or plug gaps too wide, will show at full load as there is far more mixture in the cylinders and it's more difficult for the spark to make it's way across the gap. At higher RPM coil/lead faults are more likely to show as the chance of the insulation breakdown and arcing increases if the sparks are more frequent.

Of course trying to test full throttle at 2500rpm )without the revs climbling rapidly to 5000rpm) in a cl55 automatic is interesting . Use the tiptronic to lock it into 5th and find a steep/fast hill perhaps.

The misfire only seems to be noticeable under full load over 2500rpm's it is fine if I accelerate normally up to 70ish on the motorway...

 

[grober]

I have heard of removing the maf before, if I was to do this would I then be able to drive the car?

Yes the car will drive OK on its stored default settings. Won't be great but might help to pin down the problem. I'm sure you meant "electrically disconnect" rather than "remove" the Maff since it's enclosure forms part of the air inlet system.

 

[cl55 amg]

Yes the car will drive OK on its stored default settings. Won't be great but might help to pin down the problem. I'm sure you meant "electrically disconnect" rather than "remove" the Maff since it's enclosure forms part of the air inlet system.

off course I did , could you please confirm how I remove the engine cover? and I will try and disconnect the electric connector.

Thanks for all your help Danny

 

[cl55 amg]

I have managed to get the covers off, but how do I disconnect the electrics? does it plug in (as I have tried to pull the connector) or is it the two star screws that need to be undone?

Thanks Danny

 

[cl55 amg]

OK guys managed to disconnect the MAF sensor and still the same result on acceleration so what next leads etc???

 

[tromppost]

If you accelerate with your foot right down when the car changes from second to third gear on the red line does it misfire after that, and once you have switched of the engine and started again it's running fine?

 

[cl55 amg]

If you accelerate with your foot right down when the car changes from second to third gear on the red line does it misfire after that, and once you have switched of the engine and started again it's running fine?

Not sure about the gear changes, but yes once I switch the engine off and restart it runs fine.

Regards Danny