![]() ![]() HS Engineering - I understand the calculation I use might seem cumbersome but there is a reason ) All of this obviously assumes you're correctly logging a realistic load value - In the Mitsubishi ECU this should be reasonably close to your boost pressure in kPa although it won't be exact - It's a calculated value based on mass airflow rather than a representation of MAP. Now we multiply the original AFR target of 10.8 x 0.958 to get the new value - In this case 10.35 will achieve our desired target.Īs for the ignition timing, as HS Engineering has suggested, it's possible that the ECU is applying a trim to your ignition value or alternatively the ECU may be interpolating between the high and low octane ignition tables. If you use the inverse function on your calculator or alternatively divide 1 by 1.043, this will give you a correction factor to apply to your target AFR table. ![]() There's one little trick here though as to target a richer mixture, we need the value in the target AFR table to be smaller (smaller AFR targets are richer). This means we need to target an AFR that is 4.3% richer than what we're currently targeting to get where we want to go. What you need to do is take the measured AFR and divide it by your desired AFR - In this case 12.0/11.5 = 1.043. you've run the car and the measured AFR at the same point on your wideband is 12.0:1. Let's assume you want to achieve an AFR of 11.5:1 and the target AFR value at that point in the table is 10.8:1. It's still easy to adjust the targets to achieve your actual desired aim AFR though: If I make an adjustment to the MAF calibration to correct closed loop trims, I'll make it across the board and then accept that my open loop AFR's won't match target. ![]() In open loop I don't try to chase a MAF calibration that matches the target AFR. In my experience though the karman vortex MAF sensor used by Mitsubishi is a little less affected by changes to the intake system than the more common hot-wire style MAF. Likewise if you've made changes to the intake system, this may require the MAF calibration to be rescaled to minimise closed loop trims. What I tend to do is make sure that my injectors (if you've swapped them) are correctly scaled first - The aim here is to ensure your closed loop trims are as close to zero as feasible. The EVO is a bit of an anomaly unfortunately as the open loop AFR numbers never match the actual measured AFR values even on a 100% stock car. ![]()
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