E-Class (W212) 2010 - 2016: E 350, E 550

M273 V8 P0308 Misfire

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Old 05-27-2024, 01:15 PM
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2007 CLK550 Convertible
M273 V8 P0308 Misfire

What’s up guys, I got a 2007 CLK550 Convertible. I have a p0308, cylinder 8 misfire, I’ve recently changed all spark plugs, cylinder 8 coil, even did the swap coil test and it’s still a P0308. I changed the air filters as well if that’s worth mentioning. Car turns on everyday, doesn’t hesitate, runs pretty good. On cold starts I can feel a rough idle. Almost like the car is cammed. But it’s not like a stage 4 cam. Stage 2 at most lol. After it warms up it calms down. But the misfire isn’t like horrible to the point I have drive ability issues or flashing engine light or limp mode. Car drives hard asf as in strongggggg. What could it be? My freeze frame shows that it happened at 1k rpms. So I’m assuming it’s misfiring at idle. I’ve posted on the A209/W209 forums but not a single person responded so hopefully someone here does. Thanks. 149k Miles
Old 05-28-2024, 02:16 AM
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MY'14 W212 M276 3.5NA @60kMi
low contributing cylinder

Originally Posted by ihatebmw
What’s up guys, I got a 2007 CLK550 Convertible. I have a p0308, cylinder 8 misfire, I’ve recently changed all spark plugs, cylinder 8 coil, even did the swap coil test and it’s still a P0308. I changed the air filters as well if that’s worth mentioning. Car turns on everyday, doesn’t hesitate, runs pretty good. On cold starts I can feel a rough idle. Almost like the car is cammed. But it’s not like a stage 4 cam. Stage 2 at most lol. After it warms up it calms down. But the misfire isn’t like horrible to the point I have drive ability issues or flashing engine light or limp mode. Car drives hard asf as in strongggggg. What could it be? My freeze frame shows that it happened at 1k rpms. So I’m assuming it’s misfiring at idle. I’ve posted on the A209/W209 forums but not a single person responded so hopefully someone here does. Thanks. 149k Miles
All right: you have a qualified misfire on No 8 with.good ignition on a 150kMi...

It could remotely be an injector or more than likely a drafty or compromised cylinder : bore scored or stuck rings?

You'll want to get this looked at with a bore-scope.

Last edited by CaliBenzDriver; 05-28-2024 at 02:18 AM.

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