my car is backfiring right now... when i shift... its strange. i do not have my o2 sensor hooked up, am running a 12:1 fmu, walbro pump, and inline pump on stock injectors with a drag kit.

i dont know if its still doing it... it just started today after i boosted... and did it on the way home. it hasnt been doing it before.

 

You don't have your primary o2 sensor hooked up? Do you have any CELs? Sounds like its running extremely rich.

 

i am obd I, so only one o2 sensor, and its not hooked up. i have cels obviously... im guessing its running really really rich as well.

 

You are running very rich. I say put it back on and get rid of you CEL.

art

 

FMU's cause back firing in some cases

 

check your plugs and see how they look, but yes it does sound like you are running rich, this will just verify things. fix the 02 sensor.

 

Are you sure its back firing or just the normal popping sound from a high flowing exhaust?

 

im running open downpipe, and when i shift, it pops loud as fawk, granted this was earlier after boosting, it could be fine now, ill post later.