1991 850i eml light

sometimes my 1991 850i will crank and run rough when the eml light stays on. cut it off and recrank until eml light stays off and runs smooth as silk. someone said something about throttle position sensor. does anyone know or have advice?

DK motors are probably needing a refurb - common problem with these cars.

do you know anything about throttle position sensor?

There is really no such thing by itself. The throttle positon is determined by the wiper arm within the DK motors. They send back signal voltage to the individual DME's which in turn is interpreted by the EML. The EML makes sure that both "halves" of the engine are in sync with each other. The EML light can indicate that one side of the motor is not keeping up with the other. This can be a number of things:
- DK motor getting hung up, or sticking
- O2 Sensor failure
- DME failure
- Fuel pump failure on that side
- Distributor cap/rotor faulty
- MAF faulty
- Intake gasket leak
- FPR failure
- CPS failure
- Impulse sender failure

As you can see, you will first need to try and narrow it down. Which side of the motor is not running? You can tell by which exhaust is cooler than the other after a few minutes of running. Also note that from the front of the car where the air enetrs each side until you get to the individual head, the left side feeds the right and vice versa. Once the air/fuel is in the head, then left is left and right is right. In other words, if your drivers side exhaust is cold, then you might have MAF, DK motor, or intake gasket probl;ems on the right side of the engine.

Let us know what you find.

Good luck

does the intermittency of the problem mean anything to you? usually after it cranks and runs smoothly, it does not happen again that day no matter how many times you crank it.