bank 2 is shut down

[76er]

I have a 92 750 with about 160,000 miles and the entire left half of the engine is not working. I found this out by pulling out the fuel pump relay for the left side of the engine and got no response from the engine, it still ran bad. If I pull the fuel pump relay for the right side than the engine dies. I borrowed a friends fuel pressure gauge and have 50 psi of pressure coming out of both fuel filters. I also pulled a plug wire from the left side and checked for spark and that was ok. I than pulled that same spark plug (what a PIA) and found no problems. Than I swapped the air flow meters from side to side hoping to see a change but everything was the same. I talked to a BMW tech who gave me free advice and told me to try new main relays so I replaced both of those and it's still not working. Does anyone have any advice for me. I think the next place I'll check is to see if the fuel injectors are actually squirting fuel, since my fuel pressure is ok.

[tarmak]

could be your E.M.L UNIT or your E.C.U.UNITS . YOU HAVE 2 ECU UNITS 1 FOR EACH SIDE OF THE ENGINE, sounds like your in limp mode, try changing your e.c.u units round . see what that does ,,,,,,,,,

[JimDerrig93750]

This total speculation and the original post is unclear. There are dozens of ways in which one side can shut down. Trust me, after 10 years of ownership I know :)

First, and always the first question: Is you check engine light on and if so, have you pulled the fault codes?

[@ cheung1]

76er, I think the advice the BMW tech gave you makes sense. As for injector actually squirting fuel, you can tell quite readily by the smell of the exhaust--it must be full of raw gasoline smell. I don't know if you are driving the car, but think about it: If the injectors are squirting on the inoperative side, it would be strange not to have any combustion; and your fuel mileage would be halved; and gasoline will be dripping out of the tailpipe. Yes it is possible but you won't need to check injector voltage to find out.

If your dash EML light stays lited, it is possible that the corresponding throttle (DK) motor is sticky and needs manual cleanup. There are instructions on the Internet as to how to open the throttle housing and clean the motor brushes and gears inside.
Patrick C 88 750 159K

[76er]

Thanks everyone for the input. There are no warning lights on, also no check engine light. I did however find the problem, the injectors are not firing. All six on the left side are not firing. I have an electrical schematic which shows the Motronic unit is responsible for this so I swapped the two computers around, but the problem remained on the left side. I checked the power to the injectors and it was ok. Next I used my ohmeter to check the ground wires from the injectors to the Motronic and found no problems. Unless anyone has any further suggestions I may have to bite the bullet and pay a pro to figure it out. Thanks!

[Dr. Zwolf]

Use your multimeter to do so, you should get 540 ohms +/- 10%. That did it for me earlier this year. A bad CPS will cause what you're describing. You can also swap DKs side to side; they are identical. Try these 2 things before dropping money at a shop.

[Jim 93 750]

when the bank goes into limp mode, the injectors are shut down, so all you have found is a symptom, not the problem.

If you have no lights and are in limp mode, that generally means: (1) an electrical fault in the circuit itself, which is screwing up the self-diagonistic capabilities (e.g., I accidentally switched the cyl position sensor with the crank pos sensor once and had this problem), or
(2) the problem is on the "analogue" side in that the fuel flow or pressure is way off. however, this item should not be accompanied by formal "limp mode" of shutting down the injectors--its sort of a "half limp mode" where one side is not operating correctly but the computer does not recognize it.

One more thing to check that is "outside" the diagnostic system: If your electrical system is operating poorly (alt, reg, bat), the cpu sees voltage spikes and can do all sort of weird things, including going into limp mode. However, this has always resulted in a check engine light and "trans program" warning for me.