1990 E32 Check Engine Light Help!!!

[wlerner]

Hi all,

I have a 1990 750iL stuck in the "limp home" mode. The check engine light is on. Here is my problem..

I have the Peake Research R5/fcx code tool. It gives me a reading of 0A for both DMEs. According to the manual, this code means Emission (Lambda) control.

Can someone please tell me what Emission (Lambda) control is. I am interested in knowing what part this is referring to. I have checked my air intake, the filter box, the Mass Air Sensor, and the boot exiting that. All are ok. I am at a total loss. Any help would be greatly appreciated.

Thanks!

Warren

[wlerner]

I may have answered my own question... any other opinions?

Originally called a "Lambda Sensor" when it was first used in fuel-injected European applications, the oxygen sensor monitors the level of oxygen (O2) in the exhaust so an onboard computer can regulate the air/fuel mixture to reduce emissions. The sensor is mounted in the exhaust manifold downpipe(s) before the catalytic converter or between the exhaust manifold(s) and the catalytic converter(s). It generates a voltage signal proportional to the amount of oxygen in the exhaust.


Could this mean my O2 sensors are bad? The car has 123,000mi on it and I am unsure if the sensors have EVER been replaced!

[wlerner]

Ok.. I still need some help. I discovered that the code "0A" means that the DME is receiving a voltage that is out of range. I replaced my oxygen sensors, but this did not fix the problem.

So far, we have 2 new MAF's and 2 new O2 sensors. Any suggestions?

Thanks!

[Muhard]

Hi I have an 89 750IL and I am having the exact same problem, If you have since solved the problem or have any Ideas please tell me or give me a call at 5174108394

[libertylover]

Ask over on www.roadfly.org where there is more experience.

[bimmer_fan]

hi. my 92 735i's CHECK ENGINE light comes on, too. the problem though is, when it comes on my acceleration gets affected. when i step on the accelerator when the light is on, the car is kind of like choking and the car wont speed up. but after a few seconds without letting the gas pedal go, the light will somehow disappear and i'm back to normal driving. the problem only happens though, if my gas tank has about 1/4 tank left. can anyone help with this issue? thanks.

[libertylover]

Re "if my gas tank has about 1/4 tank left" the "car is kind of like choking and the car wont speed up."

My brother used to have a Dodge van that ran well until the gas got down to about 1/4 tank. Below that, it would run poorly as you described; with the tank nearly empty it would hardly run at all! About 6 months ago I saw an explanation that seemed to make sense for this somewhere and it had to do with excessive water accumulation in the gas tank.

The "Check Engine" light comes on when your emissions are out of spec. Probably what's happening is that Mr. Computer is able to adjust the fuel mixture properly up to a point, but as the fuel gets lower the percentage of water to fuel gets higher and higher. When the water content delivered to the engine via the injectors gets too high Mr. Computer can no longer make the adjustment and the engine misfires. When the engine misfires, the emissions go to hell in a handbasket and the light comes on.

I think there are some products available that you add to the tank to help remove this excessive water from the system. (Personally, I'm skeptical that this would remove enough of the water to help much.) Failing that, you may have to remove the fuel tank and dry it out. It might help a little to change your fuel filters but I really think the solution is to bite the bullet and get the water out of the fuel tank.

*** Edited Post ***
OK, I found the info I mentioned earlier and it follows below. I also posted it into a new thread so that others who might not get into this thread can see it as well.

The following information posted on www.roadfly.org by Greg Kissell.

“Generally it is a very bad thing to run an older car low on fuel. All sorts of crud gets sucked into the fuel system.

”So yes, running the car very low on fuel could have clogged your filter(s). Clogging the fuel pickup is worse than filter problems.

”Also, especially in cold weather, do not leave the tank even partially empty. Fill up just before going home. The tank will draw moisture overnight and cause starting problems even in brand new cars. This is a compound problem since there is no way to drain the water from automotive fuel systems.

”Each night you park with a partial tank you are adding more water to your fuel. With luck it gets burned up without too much fuss but a little rough idle for a couple of minutes each morning. If the fuel level is very low, in cold weather, and the car sits for two or three days good luck getting any car to run smooth or start quickly until you fill up the tank.

”FOR ALL THE SKEPTICS
Have you ever noticed your car running SO MUCH BETTER after filling the tank? You have probably been burning condensed water vapor with your fuel. (Doesn't burn very well).”
*** End of Edited Post ***

Whether I'm right or not, please let us know what you find so we can all learn.

[bimmer_fan]

hi. bimmer_fan here again with the same check engine light problem. i really dont know what the problem is with this light. yeah, at first i said that the light comes on when i only have less than a 1/4 tank left.

well, the other day, i had a couple of misfires (cold start with a full tank) starting up the engine, it wouldn't start all the way up, just cranking. after a couple of tries, it did start but the check engine light came on. same problem...the car would drive but no power at first then normal power if i keep my foot on the pedal until the light disappears. my assumption is still somewhere in the fuel system that triggers this problem. fuel injector probably clogged? please help. or should i get looked at at the local dealership service center? thanks in advance for all the leads anyone can give me about this problem.

[jeffreyb4me]

for the 750iL guys...the 'voltage out of range' fault described is USUALLY a lean condition on M70's caused by leaking intake runner to cyl. head sealing blocks. hard to diagnose w/o good equipment BUT if you begin with a cold engine & have that center engine cover off for access, with it idling spray some carb cleaner around the injectors & intake-cyl. head area.....if the idle smoothes out or increases a little, you've found your problem. NOTE: this is though to recognize on a V-12 but it's all you can do W/O an Infra-Red Analyser.