blownrunner

I installed a OBX exhaust and headers on my 1991 ZR-1. When driving normally the car behaves very well, but when I accelerate and go about 5k RPM's it will backfire between shifts through the exhaust. Sounds like a popping noise. My guess is that the ECM is putting a lot of fuel in the cylinders and when you let off the gas to shift it is running rich and being ignited by the waste spark. Seeing the exhaust is much more free flowing there is less backpressure allowing it to fire in the exhaust system more freely. That's my theory anyway. This did not happen with the stock exhaust.

Is there any way to prevent this or is this just something I have to live with?

blackbelt

need a new chip. Your problem will be solved.

ccmano

Yes, not unusual. Marc Haibeck can set you up with a modified mem-cal chip to address that and improve performance even more at the same time.
H

blownrunner

Thanks, dudes! Called up Marc and sure enough you guys are right! Was thinking 'please don't say I have to reinstall the stock headers!'.

He will also give me the eliminated secondary tune as well, been thinking of doing that as well for a while.

1LEZ

Had mined tuned after headers. Still backfires occasionally