Here are steps for programming 0261200013 control unit with socket:

  • Remove old chip from socket (example 1267355218 or 1267355088)
  • Use eprom programmer to read binary on computer
  • Edit binary in hexadecimal and select 27 values
  • Change all selected hex values to FF (255)
  • Save binary and burn it to empty chip
  • Install new chip to socket

For one chip (1267355218) values are in address 193Fh – 1959h and for two chip (1267355088) in 93Fh – 959h. Free software for editing is available from Batronix (Prog-Express). German company also sells hardware and accessories. Changes were tested with both chips at open throttle. If everything else is replaced (air flow meter, temperature sensors, spark plugs, ignition coil, magnetic valve, vacuum hoses) and boost cut is still there this should fix it. Verifying fuel cut can be done with air/fuel-ratio meter, it happens once you go suddenly out of scale on boost.

This is needed for boosting 745i turbo engine, though stock turbo and fuel system are not going to stretch far. Replacing original fuel pressure regulator with adjustable unit gives improvement, each 0.5 bar turns up to 10% more fuel. Using rising-rate-regulator to add fuel pressure on boost goes even further, but is more like stop-gap solution on way to standalone engine management. Extra fuel is controlled by boost, not load and rpm based as control unit should handle it. Take care of maintenance items beforehand and monitor boost with air/fuel-ratio as safety measure.

Also programming Motronic between models is something to look into. At least 0261200018 and 0261200019 are possible candidates for 0261200013 binary. According to Pelican Parts article, units with same socket and software version should be interchangeable. Just eprom needs to be programmed or replaced. There is list of hardware and software versions on website. In RealOEM details for 745i turbo transmission are different, meaning specific torque converter, valve body and transmission type. This also could be difference in transmission electronics.

Update: Testing with factory rebuilt 0261200019 unit was done last fall. Original eprom was replaced with non-modified 1267355218 binary. Actually this unit used 27C256 eprom instead of 27C64 and binary was four times on chip. Alltogether arrangement worked, no afr readings were taken while testing. Idle quality was bit rougher/lower, transmission was not as smooth with sport and seemed to downshift earlier. Hot start was better compared to many 0261200013 units, no throttle was needed while cranking. Also engine was handling idle better on cold start.

Update2: Air/fuel ratios were taken with factory rebuilt 0261200019 unit and 1267355218 chip combination. Idle reading was average 15 and cruise 17 to 18, so clearly too lean. No open throttle testing was carried on due previous. For now 019 box to 013 box is no good and needs more trial if possible.