Hey all,
just thought I'd check in if anyone might have any ideas. I'm tuning a 2005 C5 with a 427ci motor/AFR heads. Car runs a TTix turbo kit with 62mm turbo's. Method of tuning is a newer style maf card with everything /2 as necessary and the tune seems to be working out well. 8 - 9 psi on a 90f summer day netted about 700whp. Although there is a lot of room to turn up the wick on power, we have a misfire issue which is yet to be solved and am hoping some of the experience on this board might help solve the issue.
Misfire only happens under heavy load (3rd gear and up) with boost. Only on cylinder 6. A hard run could produce up to 60 misfires (meaning it's not each and every ignition that misfires, but enough as it should be zero). We have checked compression and leakdown numerous times. We have checked cam lift on that cylinder, plug gap, plug, wire, coil, injector, low imp inj driver box, harness, etc (each of those components have been eliminated by removing and substituting another part). I finally got down to feeling it is a lean misfire on that cylinder. Motor uses a fast92. We took off the fast92 and installed a stock LS2 intake manifold and the misfire left cylinder 6 completely and started on #1. That is where I am currently at.
Any suggestions?
Much appreciated.