Pease Help! Problem with a BMW 750iL.
Pease Help! Problem with a BMW 750iL. I know this is not an LS1 but I wish it was. I did not know where else to post after searching the internet. 
I have a problem with a 1990 BMW 750iL, the car is a 12 cilinder running in limp mode(on only six cilinders) but then kicks out of limp mode intermittenly. I scanned the car and I have a code that say's ( Emission control (lambda) ).I have a BMW manaul but it does not mention anyting about this code or what to change, Can anyone tell me what part is bad or what is wrong? Please help!
I have a problem with a 1990 BMW 750iL, the car is a 12 cilinder running in limp mode(on only six cilinders) but then kicks out of limp mode intermittenly. I scanned the car and I have a code that say's ( Emission control (lambda) ).I have a BMW manaul but it does not mention anyting about this code or what to change, Can anyone tell me what part is bad or what is wrong? Please help! Last edited by Oatmeal; Nov 25, 2004 at 01:50 PM.
I know the electronic TB has some issues that may be related since you state that its involving one bank.
Side note when we had ours a guy I knew put a 75shot on each bank of his and the car would get sideways at 45mph! Those cars are sweet!
Side note when we had ours a guy I knew put a 75shot on each bank of his and the car would get sideways at 45mph! Those cars are sweet!
lambda is the O2 sensor.. Its probably something else. The diags on euro cars suck.. I know that BMW use to have Sun make a special machine for them, I am sure it is still the same. It will probably be cheaper to do an LS1 swap...
Lambda is referring to the a/f....it's the other term for stoich. So it's probably telling you it's too rich or lean. Check anything that could affect the burn on one side.....coil packs? Injectors? Stuff like that.
TECH Addict
Joined: Sep 2003
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From: Atlanta, GA
check our o2 sensor or wiring.
the EML system usually only kicks in if a serious problem occurrs. The two bosch motronic ecu's talk to the master ecu and reports serious issues which then shuts off the appropriate bank.
Tis a beotch of a car to diagnose. Maybe you need two air fuel gauges to see whats up?
the EML system usually only kicks in if a serious problem occurrs. The two bosch motronic ecu's talk to the master ecu and reports serious issues which then shuts off the appropriate bank.
Tis a beotch of a car to diagnose. Maybe you need two air fuel gauges to see whats up?
When I had my BMW, I could find most of the answers on the following message board http://bimmer.roadfly.org/bmw/forums/e32/
That happened to me several years ago, but I cannot remember the solution but that is where I got it.
Hope this Helps
Gordy M
That happened to me several years ago, but I cannot remember the solution but that is where I got it.
Hope this Helps
Gordy M
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I'm a bmw master tech. Anyway the 12 cylinders are lots of problems. If its in limp mode running on 6 cylinders there are only a few causes for that. 1. Check fuel pressure. The pumps are notorious for dieing, esspecailly if the car was run low on gas a lot. fuel pressure should be 3 bar (thats 45psi for the metric inclinded). The best way to splice in is under the car at the fuel filters. There is no shraider valve on this car. If you have good fuel pressure, your next bet is to either bite down and take it to a dealer or someone who can read out the codes. A dealer would be the best so you can see what faults are stored in the dme and eml control units. Depending on what faults are stored you could have faulty throttle motors (dk motors) or a faulty eml control unit. The harness on that car should be sound, the only year they had harness problems was on the 95 850 first year of the m73. You have an M70. When you tell me what faults are stored in the eml i can help you further. But from what you describe it sounds like a weak fuel pump could be the calprit seeing as you getting lambda faults and intermitent limp mode. However i have also seen throttle motors do this and eml control units if the throttle is stuck open or closed. Also if one throttle is newer then the other it is possible you won't be able to sink them together. The M70's had this stupid run in process you had to do upon replacing throttles or eml control unit. the 12's are money pits, my advice to you is to get it running on all 12 cylinders and sell it imedately.
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Originally Posted by FlyinGTP
I'm a bmw master tech. Anyway the 12 cylinders are lots of problems. If its in limp mode running on 6 cylinders there are only a few causes for that. 1. Check fuel pressure. The pumps are notorious for dieing, esspecailly if the car was run low on gas a lot. fuel pressure should be 3 bar (thats 45psi for the metric inclinded). The best way to splice in is under the car at the fuel filters. There is no shraider valve on this car. If you have good fuel pressure, your next bet is to either bite down and take it to a dealer or someone who can read out the codes. A dealer would be the best so you can see what faults are stored in the dme and eml control units. Depending on what faults are stored you could have faulty throttle motors (dk motors) or a faulty eml control unit. The harness on that car should be sound, the only year they had harness problems was on the 95 850 first year of the m73. You have an M70. When you tell me what faults are stored in the eml i can help you further. But from what you describe it sounds like a weak fuel pump could be the calprit seeing as you getting lambda faults and intermitent limp mode. However i have also seen throttle motors do this and eml control units if the throttle is stuck open or closed. Also if one throttle is newer then the other it is possible you won't be able to sink them together. The M70's had this stupid run in process you had to do upon replacing throttles or eml control unit. the 12's are money pits, my advice to you is to get it running on all 12 cylinders and sell it imedately.
. Big thanx for your help FlyinGTP, I'll try checking the fuel pump and see if the engine is getting enough to drink. 
Before you do anything with a break out box check the fuel pressure. Also i would be very careful in doing this bob idea cause the pins are very small and delicate at the eml control unit end. By the way once it goes into limp mode it will not go out of limp mode again until the key is cycled and it passes its selftest. If you can get the codes read from both dme's and the eml control unit that will be helpful esspecailly if fuel pressure checks out ok. I'm not sure if aftermarket scanners are able to distinguish that the car has two dme's. one for 1-6 and another for 7-12.
Teching In
Joined: Dec 2004
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To BMW Master Tech I used my peake tool and got OA Emissions (Lambda) Control fault code. I got the same fault code for both banks.
The passenger bank was the one that did not seem to work so I changed the o2 sensor on that side only. I cleared the fault codes for both sides and I got the same fault code again, this time just the drivers side is showing a fault code. I fired up the car, drove for 15 minutes, and it is still in limp mode.
I felt the passenger side of the exhaust it was warmed slightly but not as warm as the other side.
My friend posted the original message for me. He suggested I post myself
Any suggestion I would appreciate.
The passenger bank was the one that did not seem to work so I changed the o2 sensor on that side only. I cleared the fault codes for both sides and I got the same fault code again, this time just the drivers side is showing a fault code. I fired up the car, drove for 15 minutes, and it is still in limp mode.
I felt the passenger side of the exhaust it was warmed slightly but not as warm as the other side.
My friend posted the original message for me. He suggested I post myself
Any suggestion I would appreciate.
Whats the fuel pressure is it 3 bar (45psi)? (best place to tap in is at the fuel filters one for each bank).
How old are the distributors on it? Plugs and wires? If the fpr is all good i would take the distrubtors off and take a look and see if there deteroated.
If both those are good you need to get teh faults from the eml control unit. I'm not sure if aftermarket scanners will read this. Also how old are the throttle motors on the car. These are bascily known in bmwland as junk. Then tend to only last a few years at the best, once again i need to know the answers to these questions to be any more help.
Also you need to remember this is like two motors. It has two distributors, two fuel pumps, filters, two dme's (ecm's). Its like two six cylinders.
How old are the distributors on it? Plugs and wires? If the fpr is all good i would take the distrubtors off and take a look and see if there deteroated.
If both those are good you need to get teh faults from the eml control unit. I'm not sure if aftermarket scanners will read this. Also how old are the throttle motors on the car. These are bascily known in bmwland as junk. Then tend to only last a few years at the best, once again i need to know the answers to these questions to be any more help.
Also you need to remember this is like two motors. It has two distributors, two fuel pumps, filters, two dme's (ecm's). Its like two six cylinders.
Teching In
Joined: Dec 2004
Posts: 2
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found the solution 
I just wanted to thank everyone for their advice and tips, especially the lead to the roadfly website, this site is most helpful. Thank you FlyinGTP you have led me in right direction. It turns out I had a bad fuel pump. After putting in the new one the car seems to run better than ever.Thank You again
Sherry
