M54 Engine Lost Compression on Cylinder 6

[Auto Parts Guy]

Originally Posted by BimmerBreaker

You can run the S52 on the MS43 engine management with a few tweaks. You need to know a good tuner for that though - I know someone who can help with this if needed.

If your X5 is MS45, you may need to convert to MS43, not completely positive, I'll talk to him (converting to MS43 is very simple anyways).

That would be good to know! I would love to have a 420G in there too. At this point I'm weighing my options. Pretty sure it's MS43. That's the selection I use on my code reader. I have the S52 harness still on the engine and I think I have the ECU still. And all else is in tact. Luckily I have other vehicles to drive so I don't need a DD replacement immediately. But this X5 has been my DD for many years now..


So on to the boroscope. Not much luck there. Couldn't see much more than my cell phone would take. Once I got into the cylinder it was a dark hole. I poured a few ounces of marvel mystery oil in the cylinder and going to let it sit overnight. At this point it can't hurt. I'll put the plug back in and crank her up when I get home from work tomorrow.