codenamezero

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?

0mtber

iTrader: (2)

1.0 a/f you mean 1.0 Lamda ?

You can't always just type in a new injector size & drop in injectors.
Other things need to be tuned such as overall fuel trim, injector offsets, cranking fuel trim etc.

codenamezero

1.0 Lamda yes, it was when i first fire it up after the whole winter.

And yes, this is what i am trying to find out what need to be change, the "help" file from s300 aren't helpful at all.
So other than "current injector size", what would be the other parameters that i need to change? Originally i thought by setting the current injector size to 550, the S300 would readjust itself based on the stock 240... i mean otherwise what's the point of changing "current injector size".

Could you please give me a brief explanation on "overall fuel trim, injector offsets, cranking fuel trim"?

Thank you mtber.

0mtber

iTrader: (2)

Did you actually tune the car using the stock injectors?

What engine setup do you have?

Just asking so I can get an idea as to the history behind your question.

codenamezero

I used S300 to play with my fuel map last year, everything is stock. Everything was alright.
This winter i upgraded to a full aluminum radiator, radiator hose, 1.3 bar cap, and 550cc injector.

The plan is to tune it with 550cc first, then this up coming winter i will throw in a my turbo along with my log style manifold, DP and a GM 2.5 bar.

0mtber

iTrader: (2)

Go to http://hondata.com/help/smanager/index.html
Read the section on Fuel Trim Parameters

The help file explains almost every parameter that can be changed when re-scaling to a larger injector etc.

I recommend you disable closed loop & tune the car accordingly.

If you don't know how, I recommend you install your stock injectors until you install your turbo kit.
Once you go turbo, install your injectors & have the car tuned by a professional or you pay some one for a basemap or remote tune: http://www.phearable.net/shoppingcar...ware-c-40.html

codenamezero

I want to learn and tune it myself, I can adjust the fuel map and doing part throttle tuning... I was doing it last summer. What i need to know is just how to reduce the overall fuel being dump in the cylinder after the injector upgrade... I guess i will go try with -20% on the "overall fuel trim" tomorrow.

I appreciate your concern, but the whole point of doing all the work myself in the process is to learn how to do/tune it, otherwise i could have just dump 10 grand and just buy a complete turbo kit and have people install and tune it for me.

William Vaughan