SOHC ECU #14 #74 Difference

[707coupe]

my 240 manufactured 9/88 has #74 ecu and no air temp sensor in air box. this car had good motor, so removed it and installed in my other 240, manufactured 12/88, this 240 has #14 ECU in it and AIT sensor in the airbox. the motor runs excellent, no check engine light, no codes, timing is good, no intake leaks, but when i smell the exhaust, it smells bad.

i know it wont pass ca emmisions like that, i have 2 other 240s and i know how they suppose to smell...

both cars involved are fastbacks, base model, no sunroof. i'm assuming that the first engine (with #74 ecu and no AIT) is the lowcompression engine and #14ECU is running it wrong. my question is, do i need to swap the ecu? or harness? or both? is my assumption correct or should i look into egr and emmision stuff?


please dont flame me, i searched, i found tons of info, but noone who used the earlier engine in newer sohc. whats the difference between #74 and #14 ecus anyway?

[707coupe]

both are 5 speed if it matters, bump