It is at least 80% highway averaging 65-72 mph. I will be thrilled if I can get 22 mpg.

Does this occur only after driving approx. 15 or so miles in warm weather....guessing it's still warm where you live.

If so - suspect fuel pump.

My fuel economy has finally reached 23mpg averaging 75mph. The car still had trouble starting on two occasions after changing the O2 sensor and OVP. I tested the resistance on the crank position sensor and the values ranged from 830-2350 ohms. The specification was 600-1300 ohms, so I changed the sensor and now it is running and starting much better. I know several people said to change the sensor, but I did not want to change the sensor before performing some sort of verification test. Now I am working on vacuum leaks. Thanks, Bob.

What did you do to adjust your duty cycle? Did you adjust through the eha?

I used a multimeter and measured the voltage across I believe pins 2 and 3 in the circle port on the driver's side of the engine bay. The engine needs to be at normal operating temperature, then you use a 3mm hex wrench to change the duty cycle. Insert the wrench in the hole of the air filter cover, push down and turn screw to change the voltage. I revved the engine after adjusting the duty cycle to see if the value was stable. There are several good articles on the subject if you search the threads.

This is a most helpful thread. I too have a 1987 260E which is exhibiting similar symptoms: my car won't restart after being turned-off once reaching temperature. it cranks and cranks and I detect some backfiring (too advanced ignition?) and it will not light. Could it be a bad crank sensor in my particular case? Should I also consider the O2 sensor? -Thanks!