Recently I had a misfire issue cylinder 2 on my 09 Fit sport, initially I thought it was the cheap ignition coil I installed when Spark plug blew out of the cylinder head. So I replaced the plugs and installed a new oem coil, when I started it back up it was still misfiring. It backfired really bad then started running fine, two days later on my way home from work the misfire returned. When I got home I moved the injector from cylinder 2-1 and ended up with cylinder 1 and 2 misfire, I tested the injector clips with my multimeter and had 12v ignition power on all four clips, I had 0 on the other side from the ecu on cylinder 1 and 2 and 4.9v from the ecu on 3 and 4. I checked the resistance on the injectors and 1-3-4 were all 9.9-10.1 ohms #2 injector was 0. So the bad injector sent 12v ignition power to the ecu with no resistance, I split the ecu open last night and found two bad transistors inside. I also put a scrap yard ecu on and now have good voltage reference to all four cylinders. After doing a lot of research over the last couple days I’ve found replacement transistors and found out this problem is very common over seas, hopefully this will help someone in the future if this problem arrives again.

 

Would have been nice to give folks here the number of the transistors!

 

I will update the post when they get here and I’ve confirmed they do in fact fix the problem.

 

Just dropping in to say thank you and excellent work!
You pinpointed where voltage went in the ECU. I would have been shocked by a fault like this, and moreso if it led to the ECU. Probably would have taken me a week to reach your conclusion 😂

 

Just trying to share the knowledge my new transistors were shipped from China, so I’ll likely get them installed by the end of the month if that fixes my old computer it will be a huge win. I’ve since replaced the bad injector and installed a scrap yard ecu had it programmed and the car is back up and running.