June 2, 2004The truck has a miss at idle speed, once it hits appox. 1200 RPMS, it smooths out. no problems at highway speeds, or town driving. unless if you don`t give any throttle, then you are able to feel the miss the strongest. the computer shows code P0303, #3 cylinder misfire. so far we have performed these tests and came up with nothing.
-compression test, showed 150psi #3 cylinder
-real time compression test showed 90psi #3, 90psi #1, 85psi #2, 100psi #5.
-fuel pressure test
-fuel quantity test
-injector kill test, engine stumbled when we killed each except #3
-replaced cap, rotor, #3 plug wire, and all the spark plugs
-crankcase vacuum leak test
-checked for vacuum leaks, none found
-power balance test, #3 is the weak cyclinder
we`re gonna take the valve cover off tommorow and inspect valve springs, rockers, etc. Do any of you guys have any ideas what it could be?