M70 Engine Swap???

[masbury]

I have a German spec 1990 (1/1990) 750i. I am purchasing a US 1992 750iL engine (trying to get VIN). Can I install the '92 engine in the '90 car or will I need the DME's and EML from the donor car? I know the original DME's (DME 1.7) ended 11/91, but will the new engine run with the old DME's?

My plan is to install the '92 engine in the '90 car and drive it while I rebuild the original engine and then reinstall it in it's rightful place.

Thank you

[unity]

Will not be a problem.

[shogun]

Yes, it will run with the old DME's and engine wire loom. Many do that, as it is easier to install. Some years ago I sent a M70 chip set for the M1.7 352 to someone, as he was told that the purchased 750 had a used M70 facelift M1.7 352 installed. He installed the chips and engine did not start. Turned out that they changed the engine, but left the old M1.2 156 wire loom and DMEs and EML in the car.

Here translated from the German forum:
Chips - Problem M70
Got the shogun M70 M1.7 352 chips for my 1987 E32 750i, but with a 1993 facelift engine and DMEs and EML installed. I have changed all 3 chips. After installation of the chips I have flwg problem: I can hear the trottle valves moving when I switch ignition on and then I hear a fast tack, tack, tack clicking, maybe in the area of the distributors (?). Engine does not start, cluster indication comes on for brake pressure, oil pressure. when I try to start engine I get the warning ASC not active.
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days later: Problem solved! The cause of the problem was my own fault. When the engine was changed, I assumed that also the engine wire loom and the DME's and EML were changed to the new M1.7 version, which has 30 pins more on the DMEs, but this was not the case, the old modules were still used. Till I get the older M1.2 version chips from shogun I just installed the original chips and engine started smooth, so no damage caused by installing the wrong chips.

weeks later after he got the new / correct chip set from me: Installed the new chipset I just received for the M1.1 156 version, made a first test drive for about 50 miles. My first impression: engine started smooth, smooth idle run. Torque of engine when driving remarkable more powerful compared to original chips, no matter which gear was selected and at which speed, always enough power for sporty driving. Cruising at 70 kmh fuel consumption 10L/100 km. Then I drove Autobahn full power in modes "E" and "S", fuel consumption for those 20 km Autobahn not more than 13.1 L/100 km. Very perfect, Guys!

[masbury]

Thank you both. That's a relief! The '90 has 326K kilometers on it, I have not yet run a compression test, but it does seem to run fine. I currently have a power steering leak, which I will fix shortly.

Purchasing this 1992 engine is more of an insurance policy. My '91 850 has 166k miles on it, but I rescued that car from an abusive home, so the '92 engine may wind up in the 850. We'll see.

Thank you again. I really appreciate the feedback.