We have had an odd problem on my ’92 740 turbo which defies all automotive logic.

The Problem…
Sometimes the problem comes on while driving but usually begins when the engine is first started. It will idle fine, and accept a little throttle but if the throttle is opened more than a certain amount, the engine bogs down as though it is running out of gas. If the throttle is closed then the engine smoothes out. Now the Strange part. If the ignition is turned off, and then on again, power is instantly restored. I don’t even have to shut the engine off completely,
just, click off, click on.

We replaced:
Both fuel pumps
Mass airflow meter
Fuel pump relay
Plugs and wires
FI Brain

It feels like a fuel delivery problem to me but I am not ruling out ignition.
What parts are affected by toggling the key?

Has anyone seen this before? Any ideas? I had the same problem on my '78 240, and my '87 740t. Now this one

Thanks in advance

-Brett Anderson

I would first check the Distributer i had a problem similar to this happen to me but it happend more when driving turned out replacing the dist fixed that problem, i also had this problem when my inter cooler hose which didnt have a holes in it but was hold would collapse onto itself when i went to hit the gas sometimes, this doesnt sound like a fuel problem personally to me.

clean the throtle body. I would also suspect the tps sensor.