Help! Trying to diagnose misfire on cylinders 4 and 6.
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Newbie
Joined: Apr 2026
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2014 ML350 4MATIC
Help! Trying to diagnose misfire on cylinders 4 and 6.
So a couple weeks ago, I parked it for about an hour, and came back out to start it up and noticed it misfiring. I pulled the codes, and got codes for misfires on cyl 4 and 6 along with codes for open circuits for those respective coils. I replaced all coils and plugs, made sure everything was torque down properly and that the coils were fully seated, put the thing back together and still have the same codes and problems. Im stumped. Does anyone know what else to check? Thanks!
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
So a couple weeks ago, I parked it for about an hour, and came back out to start it up and noticed it misfiring. I pulled the codes, and got codes for misfires on cyl 4 and 6 along with codes for open circuits for those respective coils. I replaced all coils and plugs, made sure everything was torque down properly and that the coils were fully seated, put the thing back together and still have the same codes and problems. Im stumped.
Does anyone know what else to check?
Thanks!
Does anyone know what else to check?
Thanks!
You have replaced coils 4+6 with no improvement.
What about all new plugs: when ?
What about new coil boots ?
Are the 4+6 cyl. currently firing ?
How old: current mileage now ?
When was last ignition tune-up?
What is the fuel rail pressure ?
What is the running chassis voltage ?
What are the fuel trims ?
Last edited by CaliBenzDriver; Apr 19, 2026 at 08:30 PM.
Newbie
Joined: Apr 2022
Posts: 7
Likes: 1
Mercedes GLE
Misfires are very rewarding repairs. The engine torque is kept poor by lean conditions.
You have replaced coils 4+6 with no improvement.
What about all new plugs: when ?
What about new coil boots ?
Are the 4+6 cyl. currently firing ?
How old: current mileage now ?
When was last ignition tune-up?
What is the fuel rail pressure ?
What is the running chassis voltage ?
What are the fuel trims ?
You have replaced coils 4+6 with no improvement.
What about all new plugs: when ?
What about new coil boots ?
Are the 4+6 cyl. currently firing ?
How old: current mileage now ?
When was last ignition tune-up?
What is the fuel rail pressure ?
What is the running chassis voltage ?
What are the fuel trims ?
Out Of Control!!
Joined: Apr 2019
Posts: 11,923
Likes: 6,776
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
All Or Nothing
Each fuse shuts down the WHOLE BANK as follows:
Here we only have two cyl acting up, right?
This requires troubleshooting instead of expensive parts-canon without warranty.
Last edited by CaliBenzDriver; May 5, 2026 at 06:18 PM.
