Seems to be a slight knock/rattle(last about 1 second-you can hear it better from inside the car) upon a cold start(only then)-then goes away. I've changed the cam sensor-since it can cause the same symptons(according to Kirban's catologue)-not resolving the problem. Even with my Accusump/PTE remote filter-still there. I've been told it's probably a lifter(I hope!)-which I'll leave it alone. Oil pressure(with booster plate and 10W30 Mobil-1 is 20lbs at idle)in gear and 180 temp. With oil pressure at 20-30lbs prior to start(Accusump pre-oiler)- wouldn't this eliminate the possibility that it would be a cam or rod bearing-since the bearings are lubricated?? I shouldn't have any bearing failure(s) with 20,000 mile engine(I've owned it since 6000 miles/well maintained/scanmaster etc.)