my friend gave me a jdm p30 cause he said it wasnt working... i tried it out on my car and the CEL turns off and on and the car cranks but it wont start..

the CEL stays off so theres no code i opened it up and nothing looks burnt ant i checked q31 and its ok. when i put my chipped p28 the car starts perfect so i kno its the ecu


is there anything else common that goes bad besides q31 that could cause the ecu to not start the car?