Had the DME unit go bad; shop put a new one in. Car runs now, in fact runs fine. (Car is '86 635CSI, engine is completely stock.)
Except for one thing; I lost 250 RPM's! Used to EASILY hit 6100, now Rev Limiter kicks in at 5850.
Shop's not really much help, BMW North America has been less.
Any thoughts, comments, curses I can use on these people?

The ECU ends in 059.

The ECU you replaced most likely had been chipped.

Open the removed ECU and see the number of legs on the chip.

If it is the same number of legs on the chip as the replacement ECU, try to install the removed chip in the new ECU.

Here is a link to explain the issues.

http://bavauto.com/Assets/inst_pages/m30aChipInstruct.pdf (http://)

Later,

Hi.
Unfortantely, I don't have the old unit. I will talk to the shop and see if they have it. Would you mind if I showed them this message?

Ron

Once it is on the WEB it is puplic domain.

If the chip is not recoverable, consider the E-Bay clones.

They work just fine.

Later,

I think KC Ron has a good possible explanation. The thing I don't understand is, I thought even a stock '86 635 had a red line limit of at least 6500. Is that not right? I don't think I've ever seen an M30 engined car with a factory redline of 5850.

Could the tach be malfunctioning as well?

Hey.
Actually, it may have been closer to 7000. A thin Red line starts at 6250, then doubles in thickness at 6500, and runs to 7000.
I believe Tach is accurate and correct.
Any other thoughts?

Ron