Hondata

I have an s300 that when plugged into the car reads 14" of vacuum. it runs real bad when idling and free revving. it also throws a knock sensor code when there is a knock sensor present. it is not the car. i have another hondata s300 in another car that works perfect. when it is plugged in, the car idles at 20" of vacuum, no knock code. i have the socket tester, all the led's light up perfect. i have placed the ecu into several different cars and the same happens in every car. 14" vacuum, runs bad, shows knock code. the ecu data-logs and function normal otherwise. the s300 in question has the same tune loaded into it as the others to keep that a constant. what should i check?

thank you.

Have you tried swapping the s300's from the other ecus to try and narrow down if it is the ecu, or the s300? What ECU is this?

I have taken the s300 out and put it into a virgin p28. same problem. I have taken that same s300 board and swapped it into the other working s300 ecu. and it works fine and vice vs. it works fine. so I don't think its the s300. could using the wrong IC4 chip cause this problem?

More than likely you have a damaged ECU. Just put it into a different ECU that works properly.

this will be the 3rd ecu it is going into. will see if it works this time.