i have a 91 civic with a b18b swap and i will drive it and it will drive fine for a bout 15-20 minutes and then it will start backfiring and bogging, i just got new plugs but that didnt fix it i also replaced the fuel filter but still no luck any ideas?

 

what ecu? is it tuned?

 

i believe its the stock d series ecu not chipped that came in the hatch but im not sure i bought it this way its one of the floor mounted ones but the guy that had it before me was a real jackass he also had the sohc distributor that i just switched with a stock b series one

 

You answered your question. Change that ecu ASAP and i'm shure that will fix your problem. probably runs richer in the first 15-20 minutes cause it isn't warm yet, but once it is warm it leans out and causes the issues you having.

 

nevermind its a pr4 ecu from a 1990 ls its an obd0 and so is the new distributor wut else could it be do u think i just need to get it tune