# 92' 750iL rpm problems.



## No_Limit (Apr 18, 2008)

Just bought myself a 1992 750iL, so welcome me to the BMW family.

Ok, heres the problem. I'm having some trouble with my engine RPM. It just doesn't go over 1500-2000 when you go full throttle. Since the throttle system is all electrical it makes it a little more complicated.
Here's what I've done so far: 

Checked the fuel pumps, everything working fine there.
Unplugging and plugging back in the throttle wires under the hood i get max. RPM for a few seconds.
I took a full tank of fuel and the problem disappeard.

I think the problem might be in the throttle sensors, electrical valve motors or even worse, the chip might be fried.
Don't know how the full tank helped, but maybe the fuel tank is just full of **** since the car stood still for 1 year.

I'm taking my car down to diagnostics on monday, but a little advice would still be helpful!

PS! sorry for my ****ty english, haven't spoken it for a long time now.


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## No_Limit (Apr 18, 2008)

I checked the fuel pumps and measured the fuel pressure today and everything was fine. 
I also tried to reset the EML, but that didnt work.
I was told that the EML is in some kind of crash safty mode and doesnt want to snap out of it. My guess is that there is some kind of sensor thats giving it some false information but i have no idea where to look.
superman aint saving ****, need some help here!


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## TerryY (Jul 20, 2003)

Check the two rear most spark plugs. They are the ones with the spark sensor donuts on the wires.

If they show any signs of fouling replace them. Spark plugs are the first and least expensive route to go. 

If you replace the spark plugs DO NOT use the multi-electrode platinums. The V12 doesn't run well on them.

The spark plug tool in the trunk works for getting the hard one out. Either plug being fouled will cause 6 cylinders to stop running.


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## No_Limit (Apr 18, 2008)

Hmm im a bit drunk right now, but i left the battery wire unplugged and when i came here right now to test it it was all good, RPM to the max. After going for a drive the RPM **** started all over again, limp mode.
then a shut down the engine and cooled myself a lil, took off the battery wire for 10 minutes and tried it again, and it was all fine again, but after driving a little bit it failed again.

The battery is very weak i must say, can the problem be in the battery?


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## TerryY (Jul 20, 2003)

You need to be working with a good battery because the electronics on these things really don't like low voltages.

By disconnecting the battery it forgets what the problem was until it re-adapts in about 10 minutes. Then it sees the problem again and reacts to it.

It may be dirty throttle motors. They are adapted to each other in that 10 minute span.


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## No_Limit (Apr 18, 2008)

yeah, i thought of buying a new battery to it.
The throttle motors seem to be fine, because when i start the engine and hit the pedal the rpm goes right to the max. for 2 seconds approx. and drops back to this limp mode. When i remove the throttle motor relay on whatever side and plug it back in and hit the pedal the rpm goes to the max again for 2 seconds and still goes back to limp mode. I dont know if that means that they are alright, but they do work thats for sure.

You seem to be a reasonable guy, meybe you could give me some hints and tips on how to fix my car.


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## TerryY (Jul 20, 2003)

http://bmwe32.masscom.net/

http://www.e38.org/e32/

These will be important bookmarks.

There don't seem to be many E32 people on here. You might try one of the places that still cater to the E32 owner. The banner sponsor of the e38.org board had quite a few E32 owners on the E32 specific board the last time I looked.

Personally I am a V8 guy but I get to hang out with a bunch of E31 V12 owners.


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## No_Limit (Apr 18, 2008)

Thanks for the links


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## No_Limit (Apr 18, 2008)

Thanks TerryY. I found a topic about that EML on one of those pages, tried it and now it works as a V12 should
Finally i can start with the bodywork and interior. Going to build it up as a shiny stock BMW 750iL

Big thanks again, i'll keep in touch incase i run into some problems again.


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