I recently finished up swapping a custom grind cam into my 99 ls1. cam specs are 236/242 , 580/590 lift and 112lsa. I went to take it to get dyno tuned and the tuner pointed out that i was running on six cylinders. For those who are following along at home that means im short two..... I pulled the valve covers and everything looks perfectly normal. Any ideas on how i can check exactly which cylinders and what can be causing htis? Even better how can i fix it.

PS i made 313 hp and 312 tq on six cylinders

Take a spray bottle of water and put it on stream and shoot each header tube of ex. manifold near the head. The cylinders that it doesnt burn off of or burns really slow, are the ones that arent firing....every onther one that is will burn away very fast.

If you dont have a spray bottle, even dumping water from a bottle will do...just try to dump it on one pipe at a time.

Maybe you dropped the spark plugs and closed the electrode up? Check that, its easy to do and an easy fix.

Like toolatevtec said, go over the ignition side of things. It's very quick to do.

You can check the header tubes with an infrared thermometer, you should be arouns 220-230* or so. For checking ignition, I still jump back to the inductive timing light. Just hook it up and pull the trigger. Move the pickup clamp from wire to wire and verify that they are all firing.

The tuner could have done a balance test to see which cylinders aren't producing. The water or timing light options stated above should help you find them.

Why not just pull the plugs and see which ones are dripping with fuel

Most likely you didnt snap some sparkplug boots all the way on when reattaching the coil assemblies. Youd know very quickly if you didnt tighten a valve correctly

Pull the plug wires off of the coils for a second and see which two dont change the way the engine runs.