[The Blimp]

I am having a misfire on cylinder 4 and some other recent posts with similar symptoms are worrying. No codes are thrown in my case but mode 6 scan shows misfires are present on start up and rough idle.

Replaced the plug with fresh one and no change (current set was only less than 3000miles anyway). Swapped a coil and still no change.

This is what the plug looked like. Does this seem bad? It looks like something has splashed onto the top, like oil or fuel and stained the metal and ceramic. Any thoughts?

[TunafishE93]

What car? Might be your valve cover leaking that caused oil to get on plug when you pulled. If that's the case plugs don't look bad besides that, what gap you running?

[The Blimp]

It looks more like it has been washed with a thinner fluid to me but i could be wrong. I'm pretty sure its not from removal as it is baked on.

Here is a close up, you can see the discoloration.

[TunafishE93]

Yeah looks different up close.. Looks like the insulator is chipping away.. That could be a sigh of preignition which is never good.. What octane you running? tuned?

[anjuna]

The pictures are hard to determine this from, but the texture looks like what i've seen on pistons experiencing pre-ignition.

Additionally, the white color looks like it indicates a lean condition.

This is purely speculative, as it's difficult to tell, but you may be lean and pre-igniting.

[jlegelis]

What do your logs show? Are you seeing big timing corrections on that cylinder?

[The Blimp]

Originally Posted by jlegelis

What do your logs show? Are you seeing big timing corrections on that cylinder?

Its stock tune so no data logging as of yet. Will try and get some done to further the diagnosis. Car drives fine but just has a misfire at idle.

[The Blimp]

I dont know if this is normal for N55 as I have only had one since September last year but there is a noise that sounds like the valvetronic motor and eccentric shaft freaking out sporadically.

Ant ideas if this is bad?

https://youtu.be/QCRLBat2r7k

[Moisture]

if it's not the coils next you start looking at fuel pressure and injector for #4 cylinder

[The Blimp]

Originally Posted by The Blimp

I dont know if this is normal for N55 as I have only had one since September last year but there is a noise that sounds like the valvetronic motor and eccentric shaft freaking out sporadically.

Ant ideas if this is bad?

https://youtu.be/QCRLBat2r7k

Its not the cause of my misfire but I just wanted to follow up on the noise in the vid i linked.

It sounded like the worm drive and gear working but not lubricated at all. I am thinking that this engine may have a oil gunk issue as I notice the area under the oil cap has a bit if gunk near the top. I also suspect that the oil sprayer that is located on the valvetronic worn drive is gunked up and that no oil is getting to the worn drive, hence the terrible sound.

So i removed the gasket around the valvetronic motor and injected some pretty thick oil down the front of the actuator which would lead to the worm drive. Upon restart the sound was gone as I suspected. Im thinking that i should consider replacing the valve cover later this year so that I can deal with the gunked up oil sprayer. I will post a vid of the change in sound later.