Thread: Formula to get air/fuel ratio?

But its good to leave the close loop numbers @ 192 and adjust K value and latency using a wideband to get the real 14.7:1 and then tune the open loop section the tune run very smooth that way...

Someone should just make a short video of how things are done.
this may help many that are visual like myself..my $0.02

It's really very simple. Increase the fuel map numbers to add fuel, decrease to take out fuel. A wide band O2 sensor is the only way to measure AFR, not by the fuel map value.

Cheers,
Dave

Stealth 316 - Air/Fuel Flow Calculators

^That's pretty much it.

There's isn't a secret forumula floating around. The posted formulas are just rough estimates to get you close. There are too many variables for the formulas to be dead on. Tuning is still needed.

In closed loop does it matter what the numbers are? as long as there above 128? or does 192 and say 200 represent something different? Thanks

Yes it matters because those values adjust the AFR when in open loop, like during warm up, and during closed loop to keep the AFR near 14.7 as to keep the closed loop control system within range. Even though the fuel map values indicate closed loop (greater than or equal 128), closed loop doesn't start until a certain CLT is reached and the throttle is fairly steady. And yes, 200 is about 6% increase in IPW than 192.

Dave

I thought timing feedback was 128 or greater and fuel was 192 or greater. Though I do have plenty of 180's (even OEM tunes do too), which is more like -12.

With my current K value and injector size, I'm hitting more then 100 values in my WOT areas, so if I set those to 128 by accident it will lean it out? If so might need to adjust the K value way down

Maybe this is the problem I'm having then Dave.

Edit: NVM, my issues are open loop.

It is. Timing feedback in the timing map and closed loop feedback in the fuel map are both indicated by the value being 128 or greater. 192 closed loop in the fuel map is equivalent to 0 open loop.

If you have a fuel map value of 127 (max. open loop value) and still need more fuel, you could increase K, or decrease injector size, and then decrease the fuel map values to compensate, which will give you more head room to increase the fuel map values where needed.

Dave