Injector flow rate

[billiardcue]

Does changing the injector flow rate B4001 effect the car's ability to correctly compute fuel mileage on the dash display?

[DrX]

I would think that it would not, unless the IFR was not correct for the injectors being used. I believe that mine is no longer correct though as the PCM does not know that my FP is now MAP-referenced.

[joecar]

If your FPR is MAP-referenced, you need a flat horizontal IFR (i.e. zero slope)...

It's on the tuning wiki that I have to search for...

[DrX]

If your FPR is MAP-referenced, you need a flat horizontal IFR (i.e. zero slope)...

It's on the tuning wiki that I have to search for...

Sorry that didn't make sense, did it? I do have the table setup flat. But I think that there is still something weird going on. For example, when I go off the table(boost or greater than 80kPa vacuum) it seems to use different IFR values as if the table was still sloped like the stock table. So I am wondering how fuel economy is calculated by the PCM and if there could be other unseen tables that affect the calculation.

[dfe1]

I'm pretty sure this is correct-- since there's no fuel flow measurement capability, the PCM calculates fuel mileage by using injector pulse width and distance travelled. Pulse width is useful only if injector flow is known, so the data in the IFR table will affect gas mileage calculation. I found this to be true when I changed IFR values. You can also see this by looking at the gas mileage PID in the scan tool. I'd guess that manifold pressure is factored into the internal PCM calculation because it affects fuel flow for both vacuum-referenced pressure regulators and returnless systems that essentially have an "electronic pressure regulator".