Intermittent P0304 Cylinder 4 Misfire

Apr 25, 2026 | 08:02 AM

skyblue001

Thread Starter

Newbie

Joined: Nov 2023

Posts: 2

Likes: 0

GLC300

Intermittent P0304 Cylinder 4 Misfire

Looking for some guidance on an intermittent misfire on my ML and how deep I should go next.

Vehicle:

2012 Mercedes ML350 Bluetec (W166)
~160,400 km

Symptoms & Timeline

For a while, I’ve had intermittent, mild roughness at idle/low rpm and occasionally while driving.
No constant misfire, more like occasional hiccups, sometimes with a slight smell when it happens.
My scan tool has repeatedly shown P0304 – Cylinder 4 Misfire Detected (Confirmed).
EWMA misfire counts were like 100 and upto 1000 each time when it happened

I brought it to the technician, but he said there is no misfire from the computer. Any suggestions on the next step? Thanks!

Apr 25, 2026 | 02:07 PM

CaliBenzDriver

Out Of Control!!

Joined: Apr 2019

Posts: 12,058

Likes: 6,857

From: Silicon Valley

W212 MY'14 M276-3.5NA @75kMi

MISFIRING TURBO DIESEL

Quote:

Originally Posted by skyblue001

Looking for some guidance on an intermittent misfire on my ML and how deep I should go next.

Vehicle:

2012 Mercedes ML350 Bluetec (W166)
~160,400 km

Symptoms & Timeline

For a while, I’ve had intermittent, mild roughness at idle/low rpm and occasionally while driving.
No constant misfire, more like occasional hiccups, sometimes with a slight smell when it happens.
My scan tool has repeatedly shown P0304 – Cylinder 4 Misfire Detected (Confirmed).
EWMA misfire counts were like 100 and upto 1000 each time when it happened

I brought it to the technician, but he said there is no misfire from the computer.
Any suggestions on the next step?
Thanks!

You are on top of your engine performance! Misfired cylinders call for lean mixtures that guarantee heavy chassis poor driveability.

My bad... this is OM642 3.0 V6 turbo DIESEL !

Listen to Injector tickings: cloged No4 ??
Review the glow plug data no4
Cyl. compression check low ?

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Here are steps for M276 GDI Misfires :

First step is to recognize misfire means bad mixture ignition that is NOT 100% from "bad plug + coil" only. There are additional contributors to bad combustion.

> Basic misfire test steps....