2001WS6Vert

This car runs fine in all modes except racing. The LTFT looks close enough. I have played with the PE vs RPM table to no avail. If you tromp it from a stop or roll it will usually mis-fire randomly. On occasion it will actually pull pretty decent. The problem seems worse when I try to raise the boost. It seems to run better with the 2.95 pulley vs the 2.75. Timing is good with no KR. I can go 16 degrees with 93 octane or 21 with 100. I tried a closer plug gap (.028 vs .035) with new plugs, still does it. It doesn't seem to be any particular cylinder. Any ideas? It has 918 valve springs.

DarkblueTA

check your roller rockers and pushrods. We had a guy come in with a mytsterious misfires and it was a bad (read: broken) rocker.

2001WS6Vert

Yea but sometimes it pulls hard (perfect). I think it has something to do with when you just tromp on it. The blower shoots in air and the computer can't shoot in a blast of fuel to compensate like if it had an accelerator pump. I'm going back out today and experiment giving the throttle slower to see if it still does it.

TT_Vert

iTrader: (12)

i dont know if this pertains to GMs, but on my old fords w/ power adders we would occasionally blow the spark out at higher RPMS in boost. Cure was a hotter spark and tighter gaps. Perhaps weak coil or voltage to the coil packs?? Again, i dont know if this pertains to GMs>

Dave

2001WS6Vert

After messing with it the last 2 days its down to this. The car will not miss if its started from being stone cold and ran hard shortly after, but once it warms up it misses mostly from cyl. #4 and some from #3. Either the plug wire, coil, injector, valve spring or possibly valve adjustment. The guy that did the heads did a poor job and I have two different length pushrods in the motor to compensate for different valve stem heights. Maybe the valve is a little too tight. Maybe due to the expansion contraction of the aluminum head the car pulls good cold but not hot, who knows? I'm going to start switching parts to zero in on the problem