I swapped a b16a into my car, i was running a p28 chipped with a s100, i was really bad gas mileage and the car throw a check engine light. It was for the IAC and O2 sensor(code 14, 41), so I opted to replace the O2 sensor and IAC also get the correct ECU. First I replace the O2 sensor, the check engine light went out. IAC codes would still come up, now i just put the p30 in and it throw a code....23 which is for the knock sensor and no other codes, so far. Any suggestions?

 

either your motor does not have a knock sensor on it, or your car/engine harness isnt wired for it, or both

 

P28 = no knock sensor board = no knock code
P30 = has knock sensor board = knock code

really bad mpg due to not tuned correctly or at all.

the IAC code may be delayed with the P30. Not all codes are instant.

 

That's the conclusion that I came too, after leavin the P30 in. The trouble code for the O2 sensor eventually came on, so I replace my old O2 sensor and the mpgs returned to normal. Still haven't replace the knock sensor because I haven't had time, but I have the part. As for the the IACV, that code never resurfaced so who knows.