car bogs out and back fires at high rpms. around 6500. what could be the cause ?

 

If it is a stock engine, you are reaching the limit of the valve springs and cam. Also the ECU is programmed to abruptly cut the fuel to the engine around that point to reduce the risk of damage.

 

it really depends what engine u have if its somethin like the d15b7 then thats really close if not at the fuel cut off point ive never gotten mine that high but its an auto. but if u have a z6 or y8 of other 1.6 then u should be able to rev freely to around 7200

 

its a z6 head on a d15b block and it didnt use to do that...i didnt cange anything my ecu isnt running on stock map is chipped and programed. I use to reach redline which i set @ 7500 rpms no problem but now like i said it boggs and backfires around 6500-6750 untill redline