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Although the throttle position sensor is important, my impression is that it won’t make a difference as to the engine totally failing to start or run.
The throttle cable end that is attached atop the motor rotates a shaft. Its position is sensed by the throttle position sensor. Following this logic should make it easier to locate the throttle position sensor.
The throttle position sensor is different for mid-1980s BMW cars with the ZF 4 HP-22 EH transmission. This is why it’s such a rare part.
The following pictures show the dust cover that covers the throttle position sensor.
A vacuum hose runs on top of the dust cover. That hose is in the way, so I removed it by gently pulling it off.
I removed the driver side long screw that attaches the backing plate to the throttle body. When I pulled the screw out, some spacers came loose. They tend to fall, so you might want to be ready for that.
Before I could remove the strut, I pried off the diagnostic plug cap, and then I used a flat-tip screwdriver to remove the clip that attaches the diagnostic plug to the strut. This enabled me to remove the strut while leaving the plug in place, attached to its nicely flexible wiring.
Here is a picture of the strut, cap and clip, removed from the car.
The mechanism relies on a black plastic spindle that’s mounted on the eccentric axle that runs through the throttle body. It’s a friction fit. To remove it, gently pry it away from the throttle body and slide it off the axle.
Re-installation is the reverse of removal, though you might need to tweak the position of the new throttle position sensor so that it correctly senses when you’re at idle, and when you’re at “wide open throttle.”
You can hook an ohmmeter to the parts (and NOT to the wiring) to check the values, to see when the parts register the relevant throttle positions.
You don’t need an assistant to step on the throttle pedal because you can simulate the throttle pedal action by yanking on the accelerator cable, the end that’s on top of the valve cover.