Alrighty, I'm finally starting to get into the tuning part of being FI. I ordered the PLX Devices M-500 wb02 setup and it should be getting here shortly. With that I'll finally be able to get an exact air/fuel ratio right on the display.

My question is, what a/f ratio should I aim for? I know 14.7 is stoich which means that is where the gas is burned fully or something like that however I remember reading somewhere that having it at about 12.5 is good for the best power. Since I'd be using the s-afc to fine tune it and since the s-afc has two maps I can use on it I'd like to set one up for fuel economy and the other for max power. So, for fuel economy would I try keeping the a/f ratio at 14.7 and for the power file 12.5?

Thanks in advance!

 

im pretty sure if you set your A/F @ WOT for 14.7 you will detonate. you want it to be at 14.7 when your ecu is in open loop which i think is when your tps voltage is below 75-80% because your timing will be more conservative

for economy i wouldnt go above 13 and if you have it on that setting i dont think id be a good idea to get on it hard

for power i would stay below 12.5 to be safe

 

yeah, for the economy setting i wouldn't be spooling the turbo much at all. i'll try those out when i get the unit and see what i come up with.

 

IMO just tune under boost....probably from 3-3.5rpm and up...just shoot for 12.0-12.5. IMO unless there are serious off boost drivability issues due to larger injectors, etc., partial throttle tuning isn't that important.

 

i at least need to get it within a reasonable range. at the moment my gas mileage is suffering very badly at something like 14 mpg or so. most likely the a/f ratio is even lower than 12.5 so i'll get it up to 12.5 or so and see if that improves my fuel economy at all.

thanks for the help guys.

 

well I've never done partial throttle or off boost tunig( I usually just interpolate the whole map and tune the boost), but I'd assume just run 0 boost(open WG) and tune for 14.7 in the part throttle low RPM(probably under 3,3.5-4k rpm or under 80% throttle)than as you reach the boost transition wind it down to 13 and eventually 12/12.5....thats my guess

and also how exactly does the AFCII "dual map" work??

 

good **** here too...

http://www.hondata.com/techpartthrottle.html

looks like you'll wanna take ignition timing into consideration as well I'd guess

 

On my safc2, there are 2 'maps' you can set it to. For each map there are 2 settings though. One is for low throttle and the other is high. Lets say you set it at 40%. So when you are at less than 40% throttle the safc will be using the low throttle setting. When you stomp on it and it's over 40%, it will automatically use the high throttle setting.

 

Interesting, I didn't know you could tune low throttle with an S-AFC/S-AFCII. I was always under the assumption the S-AFC didn't do anything unless you were at Boost.

S

 

yeah, you can somewhat tune full and partial throttle with the s-afc. there is something like 12 rpm points that you can set for a certain area of the throttle.

like said above you have a low throttle map and high throttle map. you can set those points to change just about wherever you want. i believe mine is set to crossover at either 50% or 70%, i can't remember which. once i get to the crossover point it will automatically switch the fuel map to the high throttle fuel map and keep it a bit richer (or however it is set to be).