As the simple reason a/f 14.7 is best economy ; a/f 12.5 is best power . How about the fuel map as attach ? Give lower TPS an RPM a close loop for a/f =14.7 , otherwise a/f=12.5 .
Kindly let me know is it suited for car ? ?
http://i117.photobucket.com/albums/o72/alexhs/afm.jpg

12.5 isn't always best. Depends on the motor. It also depends on the motor how much fuel it takes to get to the target A/F. The ecu in these cars is not smart enough nor does it have the equipment (wideband) to be able to self tune to a target a/f like you have in the graph.

Can u tell a bit more about what condition should use what target A/F ratio ? My idea is base on the diagram below. So I want to tune target A/F ratio =12.5 using wideband o2 meter let motor got best torque and power in open loop .
Before implement I want to know what flaw is so that no experts to do it ?

http://i117.photobucket.com/albums/o72/alexhs/afr.gif

Well I know for sure I wouldn't really want to be running my turbo car at 12.5. So I mean it differs due to engine aspiration and overall design. That is a general picture from Toyota and its from a sales brochure so take it lightly. Is your motor turbo or naturally aspirated? Your overall idea to tune closed loop to 14.7 and then to another a/f to make more power is sound and a good idea.

HUH...I understand and many thanks, my stoke is SR20VE @ Primera :)

Alexhs,

1. You live in Taiwan but your Nick/Handle indicates you are from.. Greece or Russia ?

2. Setzer indeed pointed correctly that you should not take guideline-numbers too literally. In your case with an otherwise stock engine, it has been shown on dynos with wide-band O2 sensors that SR20s respond very well to lean AFRs close to 13-13.3.

Hi Hpro123,
I am sure I am Taiwanese :) . The point you mention is very useful to me so I will also try leaner and many combination during road driving .

OK on the "point-of-origin" !!! :-))

How are you tuning it? What SW, what board?

common daughter-board with rom editor to modify :)

OK, good enough.

Points:

1. What you see in those tables are "estimated" or "target" AFRs assuming every part in your engine and everything else operates as it was designed / specified to. Unless you do actually measure the resulting AFR these remain estimates, guesses.

2. After those "target" AFRs are calculated, there are still several factors that are taken into account that alter the fuel injected resulting in yet a different "final" AFR (engine temp, how fast you press the gas, etc.).

3. Finally, no engine likes switching from a 14.7 AFR directly to a 12.5 (or whatever AFR). It bogs, "holds", surges, jerks, whatever. The transitions from the 14.7 to the 12.5 areas need to be smooth. On top of that , the ECU interpolates the actual value it will use for injection by taking into account values from surrounding squares in the map (this acts like smoothing as well), so changes in a specific cell affect all surrounding cells as well.

And a question?

Where did you get the board for the SR20VE ECU from? PM with details.

TIA.