having a misfire problem following each 4k rpm or higher run...

have already checked plugs, wires, coils, injectors, flushed oil and added fuel cleaner.

thinnking it is a weak valve spring or bad lifter....

hoping a compression check will show something.

how do i check it? pull the fuel pump fuse and just crank the engine with the plug out?

or is there another way?

 

Don't know, but make sure your car will not start during cranking and be sure you block the throddle wide open during the test so the car get's air.

 

what if i disconnect the coil pack connectors? this way none of the cylinders get spark.

somebody has to have tested compression on an LS1 in here!!

 

This was written for the LT1, but should still work for you. Maybe a minor change or two.

 

i should have known you had a writeup on it

said it once and i'll say it again....shoebox you are "the man"