i'm gonna bump this for you Tue.

he pulled the pan and checked and cleaned it and the oil pickup.

checked the CEL and is getting code 21 - spool solenoid. code 21 ONLY.

checked resistance and voltage to the vtec oil pressure switch - within spec. (plus code 22 is vtec oil).

engine was making 75psi pressure when it was in my car (was pulled for swap).

checked resistance of the solenoid to ground - 15.5 ohms (within spec of 14-30 ohms).

jumped the solenoid and it clicks. however, when car is running and solenoid is jumped, idle does not change.

however, 2 out of 10 times he jumped the solenoid, idle did drop and the car stalled - tells me it works sporadically.

so, my assumption is the solenoid is sticking/faulty and is causing the CEL code 21 for the spool valve. this means the solenoid needs replaced.

he is going to do some more diag and thinking tonight. any other ideas?