Thread: Misfire after build.

Originally Posted by JerzNick

I finally finished the build. Installed the following mods:

XP-Cam
CompCam Lifters
Ported Gen 3
Ported TB
Ported Heads
AutoLite 104's
3.25 Pulley
Speed Daddy Headers
Wideband o2

Started it up and it idled perfectly! Opened HP Tuners and started Scanning while I drove for a half hour or so. Without boost the car seems to drive pretty good. The instant I make the slightest boost, it starts to misfire. Not only can I hear it in the exhaust but HPT sais "multiple random misfire". Again, it only seems to happen when throttle is 50% or more... I tried APP606's to see if the plugs would make a difference but to no avail. any ideas???

Thanks in advance

Your build sheet looks.... identical to mine. lol