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

Jaap

Read this:
https://mbworld.org/forums/cl55-amg-...8-low-rpm.html

cruiser02

Don’t drive it like that, it WILL cause permanent engine damage.

It can be O2 sensors, I would get new ones.

BOTUS

in the interesting link above the guy replaced everything - in the end ran normal for 40 seconds then played up at idle only ever on cyl 8 - but never funny anywhere else


spark plus
compression test
CAT sensors
new engine ECU
inlet manifold
injectors
ignition coils (twice)
everything multiple times

in the end a guru rest some adaption and it vanished - only to come back days later on cyl 4 rather than 8

so deliberate mischief in software SOMEHOW ....



.

trigital

As anyone can drive fast, the most complicated is to drive smooth and slow...I would start measuring the fuel pressure at idle and intake manifold air leak.