Are these STFT normal? Looks really really odd!

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Does this look right? Look at cylinder 6 also how much it misfires. Not triggering a CEL but still felt.

The fuel adjustment is almost max. Missfire would depend on if it was still climbing when you were looking.

Both banks 3 and 4 are over rich. so the one bank is very rich. It wouldn’t be a bad idea to smoke test.

Misfires were climbing only on #6. Would go away once i gave it a bit of gaspedal moves or opened up the oil cap (+25.8%). It’s really weird because as you can see 7,8,9 are not affected by it. It also happens very randomly which is even more confusing. Has it anything to do with the cylinder coating? Lots of German guys say that these early BXA/BSMs have a notoriously bad coating.

The cylinder has no effect on this. The cylinder coating would have more to do with oil consumption and perhaps compression.

The is a pre combustion issue. The fuel trims are getting disturbed greatly and this effects obviously the combustion. There are many factors on why other cylinders might not be effected. Do you have a fully working intake manifold?

Yes, the intake manifold is just 4000 miles old. I have to remove the motor pull brackets yet since I’m running the JHM spacers. But prior to that it also was only cylinder 6. The injectors are also knew and last week I’ve swapped the HPFP which made a difference for about a week but then it started again. Y plenum is also new because there was a vacuum leak.
What me and all of my mechanics are asking ourselves is why only one cylinder is affected. Compression is very good on that one so we’re about to fully scrap the car if it gets worse.

Has the fuel rail to do anything with that? VCDS showed something very strange.

If the injectors are new that helps as from time to time you can see injectors not flowing the same. Still with this your issue isn’t under flowing injector it’s a rich condition.

I’d smoke test just to help make sure there are no leaks as there is probably going to be something leaking to cause this. The other side that can get the misfire is a bad or low flowing cat. They get damaged over time on these cars and can cause misfire issues as well.

Is there a way to check the cats? Let’s be honest the car has 130k miles on it and is 16 years old. I’ve always suspected that it might be the cats.

Crack clike this can make big issue…

Checked mine last week it’s still good no cracks at all from what I can see. Still wondering why it’s only one single cylinder…compression is good and it’s very random…I’m about to trash the car all along I’m that close already.

I’d remember a few things. That a PCV hose or small leak at the throttle body can cause misfires on single cylinder. Not really sure the rime or reason. Is this misfire all of the time… or just on start up

Mostly on random start ups and during stops a little bit but that’s also very random. I’ve revealed the TB connection because in fact I’ve had a leak there. PCV hose still looks good under that mesh. However i can hear a sucking noise around the area of the suction jet pump and once I pinch that little hose that connects to the Y plenum it’s gone. And maybe it’s just me being paranoid but it have a gut feeling that these misfires mostly accure when I press the brake… shouldn’t make any sense but once it make an emergency brake it runs buttery smooth…

Funny story: last week I held the brake pedal and the gaspedal at around 1000-1300 rpm and managed to get a misfire code for every cylinder on Bank 2…

Sitrep: the misfire stops when I shortly Rev the engine out and it runs smooth as if nothing ever happened. Can’t do that on a cold engine though. But I think it might have to do with the fuel supply…

If it goes away when you give it gas and you have messed up fuel trims. Those two right there kinda give you a good road map. It might be worth swapping injectors just to eliminate that