Dear friends, Did a rebuild on a 1998 L31 vortec K1500 - I also added a slightly larger camshaft with 203 - 203 duration - 450 lift with 1.6 rockers and a 112 Lobe sep. ( Basically mid 1990s corvette intake lobe on intake and exhaust - Delta Cam recipe from tacoma wash) ( last motor before rebuild broke a piston from water lock - leaking intake manifold)
1) I have had a random misfire code - looked at it on HP tuners and noticed I have a couple cylinders misfiring intermittently , also got a catalyst code on #2 on bank #2 - which would seem to confirm the misfire.
2) truck also stalls when cold and selecting from park to drive - like a Idle Air control sticking ( replaced that to no effect) Cold start issue goes away with warmup.
3) The MPFI was replaced 5 year ago before the rebuild - believe was the electronic california kit
QUESTION:
4) thoughts on the misfires ( have replaced cap, rotor, distributor, and wires - going to do plugs next ) ? MPFI ? Leaking intake ? intake manifold gasket was replaced with rebuild - IE claimed novel intake fix feature for the vortec. But I just topped off coolant which was low to my suprise - so seems to suggest a very slow leak.
5) replace intake and redo gasket?
6) Thoughts are the best approach for tuning this new camshaft - runs fine enough - good power - could never light up tires before - can now ( thinking would like to get as much as I can out of this cam ) .
any thoughts appreciated - thanks