hey..my friend swapped in a 2nd gen b16 in my 93 civic hatch si...when i start the motor.the muffler makes little popping noises,kinda like its back firing..... and the rpm needle bounces from half rpm to almost 0..the other is...when i drive it...when i accelerate the car,it boggs badly...it is throwing cels..it gives me 2 long blinks then 3 quick blinks..i was told its code 23 which is knock sensor...i asked my friend if he wired it.he said no..so i did it myself..i ran a wire from the knock sensor to the ecu,pin d3 but its still throwing a code and still boggs..i tried using the stock p28 ecu.it doesnt throw a cel but still boggs......can anyone please help me,thank you.........................if anyone wants to know..i just bought the b16 last week at hmotors in burbank,ca......PLEASE HELP ME

 

Check your ground wires. alot of times people forget to reconnect this. It is towards the back of the engine on the thermostat housing.

Other then that I'd say you miss connected something.