I've been getting the trouble code 4 ever since I installed a new distributor. I've tried 3 different ones with the same result. The car runs fine until you get over 3500rpm and then the check engine light comes on. The interesting thing is that when I reset the ECU to clear the code 4 one time I didn't follow the procedure I read. This time I took the negative cable off while I was eating dinner and then reconnected it and took off. Somehow this caused the idle to surge when warm but the code 4 never came back. I reset the ECU again a couple days later and the idle went back to normal but the code 4 came back.
Is it possible to bypass the crank angle using the cylinder one position sensor? Or is the ECU looking for these two inputs to be different?

 

I had the same problem with a DOHC ZC motor. Ended up replacing the ECU and that fixed it.

 

If you weren't having troubles before, and you've tried a few distributors, maybe check the harness side of the plug for a loose terminal. then check for continuity between the plug and the ECU. You might have a loose connection in there.