Just was Dyno'ed; they say I'm too lean

Power-Tripp said:

You are getting all wrapped up in the "mg of air" units. The ECU uses a conversion factor to relate the numbers in the F and L tables to an injector on-time. so, just think of the numbers in the cells in each fuel table as injector pulse units that relate to a specific amount of time that the injector is open.

Click to expand...

If it is mg of air, then what is the conversion factor and where does the ECU get it from?

dougl said:

If it is mg of air, then what is the conversion factor and where does the ECU get it from?

Click to expand...

It isn't necessarily in the ECU software. It is in TuneEdit software. They are not the same thing. One is code in the ECU, the other is interface software.

If you target a specific air/fuel mixture ratio (AFR or Lambda), then you can use simple math to determine how much fuel is required for the correct ratio. It doesn't matter if the units are pounds per hour, or mg/second.

If you mean converting to IJPU (injector pulsewidth units), there are a few assumptions made by the engineers, but you need to know output, BSFC, VE, injector flow, injector dead time, fuel density, etc. to determine a somewhat accurate IJPU conversion factor.

That is why I prefer simply starting with IJPU, and not some VE or air mass unit. Not all software engineers feel the same.

Man. This is just all way over my head....

I just don't want my engine to burn up from a lean condition.

Were the dyno runs done at full(100%) throttle--as is usual for a dyno-day? If so you only need to change the fuel trim in the 100% TP column in the 2000-4000 rpm range,and the second run was actually not bad.