I've just replace stock chip in my PW0 with modified one. I created the custom chip by modifing fuel map and uploading it the chip.Than I installed chip in my PW0 according to the instructions You can find on the internet. The problem is that after connecting ECU to the car, red test light inside the ECU is lighted up permanently. I can't find such error code anywhere. Engine started and were reving properly, but after Vtec started, check engine light appeared. Have You ever faced similar problem and what was wrong? Any ideas? BTW: I used 27c256 chip to replace the stock one unit.