1995 540i limps home

[Clarksonvalley]

1995 540i 6-speed, 228,000 miles. Got an 'O2 sensor' fault, so I replaced both sensors and also replaced the spark plugs. Work complete and took it for a ride - ran great. The next morning, the power went away after driving 1/4 mile. When I fed in any throttle, the power died. I was able to limp home at slow speed. I used a code reader to find the fault codes as follows:

code 34 - Ignition Coil #5
code 18 - Ignition Coil #4
code OF - Ignition Secondary Monitor
code 32 - Ignition Coil #3
code 16 - Ignition Coil #7
code 31 - Ignition Coil #2
code OC - Oxy. Sensor #2
code C9 - Lambda Control #1
code Od - Oxy. Sensor #1
code Cb - Lambda Control #2
code 33 - Ignition Coil #8

The ground wire to the ignition coil on each bank is attached and the electrical plugs to each coil are seated. I've replaced plugs and O2 sensors many times in the last 20 years, but never a problem like this. I'm using Bosch #13523 O2 sensors (from BMA Auto Parts in Glendale, CA) and Bosch #FR 7 LDC+ plugs.

I have never had so many fault codes at one time. Anyone have any thoughts - sounds like a failure in the computer, but it's strange that it happened after the work mentioned above.

Tom

[ahlem]

I'd check the fuel pressure. Some times you can get fault codes on the way by while the engine is stalling for other reasons. Also major vacuum leaks.
I had an issue with an O2 sensor that had the wire splices in it rather than a new wire all the way to the plug. Those little gray screw connectors didn't keep contact and it caused a similar situation on a 535.

[Clarksonvalley]

I do not see a 'fuel pressure failure' in the fault code list, but I do have a fuel pressure gauge and will check the pressure. I can't help but think that the work I did has something to do with all of the fault codes, but I cannot think of what it would be, especially since it ran great the day of the work and ran like crap the next day.

[ahlem]

Maybe your O2 sensor connector came loose? Can you put them on the wrong plug? Mine only has one sensor.

[shogun]

Maybe your O2 sensor connector came loose? Can you put them on the wrong plug? Mine only has one sensor.

M60 has 2 O2 sensors and pretty often people mix the sensors up and then the reading goes to the "wrong" place. For example if the bank 1 sensor is connected the wrong way and it sends the signals to the Motronic the adjustment is done in the wrong place for bank 2. Had that also on my 750 E32. Have done such replacement quite often, but it happened when I was in a hurry.

[Clarksonvalley]

Shogun,

Sensor #1 is drivers side, Sensor #2 is passenger side. I have replaced both sensors and the electrical connectors look good, not cracked or broken and the two parts seat all the way in. Will look into the fuel pump - I think it is probably way beyond its life span - 228,000 miles and it is the original pump.

[shogun]

Good idea, 1 pump and 2 fuel filters http://www.realoem.com/bmw/enUS/part...BMW-540i&mg=16
M60 needs 3.5 bar fuel pressure.
Do not have the other data but should be similar to the ones for M30 and M70, except the M60 needs 3.5 bar, for reference only here:

nominal Bosch pump data M30 and M70
The M30 fuel pump is originally Bosch 0580464995, operating pressure is 3 bar, conveying capcity at 12 V 1.9 liter/minute, conveying capacity against counterpressure 875 ccm/30 seconds, Power consumption is 5A

The M70 has 2 pumps, so 1 for 6 cylinders, each: Bosch part number is 0580112507 (according to an old repair book), operating pressure is 3 bar, conveying capacity at 12 V 1.7 liter/minute = less than the M30 pump
capacity against counterpressure 875 cc/30 seconds, power consumption 5.5A

[Clarksonvalley]

Where is the 3.5 bar pressure taken - at the pump outlet? - at the fuel rail?

[shogun]

see workshop repair manual section 13 31 029, delivery pressure of fuel pump - check , install tester in fuel line in engine bay upstream of pressure regulator

https://www.bmwtechinfo.com/repair/main/

[Clarksonvalley]

Would a good place for the pressure test be at the steel fuel supply line in the engine bay where it connects to rubber tubing?