On the other hand though, however this anomaly happens in my case from a dead stop. If you commit to a full throttle and time it right, combined with the super short 1st gear that the manuals have, and at least on my build. You’d better hold on to the wheel tight, and not bounce it off the rev limiter excessively.

So it’s not like it’s misfiring or running poorly, which the live data proved. It actually makes for a great launch, without aggressively dumping the clutch.

In any event, I don’t drive my X that aggressive anyway.

I am glad you found the problem. My Bremi’s were shot early on.

Did you disconnect/reconnect grounds? It's a not too uncommon issue for coils to malfunction when a ground is loose and if memory serves, multiple coils share a ground so a bad ground can affect multiple coils so hopefully reworking those connections will be resolution.

Scuffing the grounds helps as well. The cleaner, the better. But as Andrew said, keep the grounds tight! A loose ground can even possibly cause damage.

UPDATE
Turns out it was my front drive shaft splines wearing out causing bogging down/slipping. Solution is 1 inch longer front drive shaft splines.
New drive shaft on ebay or https://www.tcbmwx5.com/ around 400 or you can take your old one and cut it and get a welder to put a 2 inch extension but needs to be balanced and I just bought the whole new one.
Also bought
New Giubo
New Giubo bolts and nuts
E12 torx socket
3/8 extended flex head wratcht
grease for new rod
Instructions https://www.youtube.com/watch?v=id5T...TCBMWX5.COMCEO
Tips https://www.youtube.com/watch?v=fEpt...channel=50sKid

I have 260k and 17 inch rims so your mileage may vary.
Figure out your parts from https://www.realoem.com/bmw/enUS/select

Looking at all the posts, and seeing what you found was the problem, the Aww hell no, Really! comes to mind. Iwas just going to suggest check your fuel filter aas it was not mentioned and it was pexectly what caused the same problem with mine.
Glad you are up and running again, there is certainly a mountain of knowledge and experiences in here, that is for sure.

I ended up giving up trying to get front shaft into my old transfer case, I bought a new shaft and rebuilt transfer case from https://www.tcbmwx5.com/
check your splines, if they look like mine below, you need a transfer case. 4 hours of filing did not work due to the first inch of splines were half broken off and the torque kinda bent them, no way to get it in. 4 days of trying and figured with 260k prob worth it to get a rebuilt. Plan on keeping car for another 5 years so will see.

after filing for 4+ hours with small flat and square files.

https://i.postimg.cc/6QjS9d23/PXL-20...-052046269.jpg

It looks like the original shaft never was in there that far... I get hand cramps thinking about filing that much at my age :rolleyes:, the end of the transfer case looks like it was hammered a bit as well or is that an optical illusion?

bmw updated the design in 2004, but 2000-2003 had a 1 inch spline, updated kit is 2 inch which fits and how it should have been. V8s strip them at way less miles.

If you had the longer shaft and couldn't get past the damaged splines, the solution would be to cut off the damaged part. I would use a rotary tool with emery stone. Or replace the output "shaft" if you can get that part by itself.

Also; I made a tool for cleaning up hub spline from an old CV axle. Possibly the same can be made from the end of your old prop shaft (cut off the damaged end and have some nice squared off teeth to use as machine cutting tool).