Hondata

Hi guys, I've just change my injector from 240cc to RC 550cc.
I went to Parameters -> Fuel Trim, and updated the "Current injector size" to 550 and left the stock injector size value as 240, and uploaded the new ROM to my ECU. I am facing the following problems:

- First time i cold start my car, it seems to idle fine and A/F was ~1.0, after the temperature went up, i shut it off.
- Right after, I fire it up again, but now i am having a super rough idle, and A/F shoot all the way to max, so obviously my injector is dumping fuel... looking at the log, it seems to be dumping 20-25% more fuel than it needed.

My question is, what do you need to change in s300 after increasing the injector size?? I thought the "current injector size" would've taken care of it, but apparently not.

Also, why would the cold start idle (left it running for 10 minute) perfectly fine with steady 1.0 A/F, and after i turn it off and start it back up, my injector begin to dump fuel?

No you have to fine tune the fuel table to get the right AF ratio under all driving conditions.

After playing with it for a day, it turns out i could get a stable idle by setting the Overall Fuel Trim to 25%.
With that out of the window, i could tune my fuel table just like how i used to do it last year.

What i did was to set the Overall Fuel Trim to 10%, then upload it. I saw the Lambda dropped from 1.36 to ~1.24.
So i set it to 20%, it drop a bit more down to ~1.06, then i just settle with 25% and it gave me a steady 1.00 Lambda at idle.