little back ground on the car. 3rd gen camaro with a 5.3/th400 with twin's on it. 10 lbs of boost, brought it to the tuner and everything was perfect for the street tune but when he puts it on the dyno it starts to break up under a heavy load.

car drives fine when just normal driving but when you really lay into it when cruising in third it starts to break up at about 4500-5000 rpm's

i have changed plug wires, coils, plugs (tr6's)

not sure where to go or what to check next. i talked to my tuner this morning and he is rather stumped at the moment and doesnt know where to go. when it was on the dyno afr's are good on the drivers side but cannot check the pass side since the 02 sensor is locked up in the bung.. so we are assuming its on that side but not 100%..

any help?

 

Hook up a fuel pressure gauge at the rail and watch it as the RPMs climb. It should show constant ~58psi all the way up...if it drops at all you have a fuel delivery problem.

Also use a scantool to watch both Spark Advance and Knock Retard. If you see KR start incrementing, and you've ruled out a fuel delivery problem, your main timing table will need tuning downward.