Forum » Road Tuning » Tuning Target Map and Fuel Calibration Map

Tuning Target Map and Fuel Calibration Map

Road Tuning

Discussion and questions related to the course Road Tuning

Page 1

Hey Andre,

In your road tune course it goes over tuning the MAP VE tables, correct? As you know tuning an EVO X with the stock ECU is not quite the same. For one I cant do the breaking technique you do, the car ECU does a cut to the TPS when I do that. And as far as I know there is no logging just the MAP tables or MAF tables and adding/subtracting fuel on demand like you did. I believe this is all done by logging STFT and LTFT.

With that said I am looking for some help/advice on tuning the HOM (High Octane map)"Target Map I think" and the CFM (Calibration Fuel Map) "I think this map is for adjusting the High Octane map to the number you set it too". Example if the HOM is at 11.5 AFR but the Wideband said I am running 10.5 I would then increase the CFM % down to remove fuel. At least that's what I have been doing.

I've found it to be much harder than it seems tho. So what I have been doing is just adjusting the HOM to get to 11.1 AFR or for what my target is. Then I adjust the CFM if I cant get the HOM to adjust any closer.

Attached is a screenshot of both Tables and what they look like on ECUflash.



Attached Files

While you can't perform the braking technique, this strictly shouldn't be necessary when reflashing as your life is actually much simpler than tuning a standalone ECU. In most situations you won't have any work to do in the idle and cruise areas as the ECU will be running inclosed loop and until you start messing with the intake or fuel system, you 'should' have nothing to do. Generally if the fuel trims are within +/- 5% I would leave everything alone and focus on the WOT tuning.

Your tuning for WOT should be done in the High Octane Fuel MAP which is essentially a target AFR table. The problem is that you can't consider the target AFR numbers as absolutes. For example if you want to run 11.5:1, this doesn't necessarily mean that you can just blindly plug the number 11.5:1 into the map and assume everything will be fine. What you need to do is log your actual AFR and compare that to the target AFR in the map. Using the 'Measured / Desired' formula you can then calculate the required target AFR to put in the map.

For example let's assume you want an AFR of 11.5:1. If you are measuring 10.8:1 and the value in the target table at the same point is perhaps 11.8:1 then you would perform the following calculation: 10.8 / 11.5 = 0.93. This means that we need to remove 7% fuel (1.00 - 0.93 = 0.07 or 7%) to achieve the target AFR of 11.5:1 so we can apply this same percentage change to the target map. In this case 11.8 x 1.07 = 12.6:1.

If you now change the target to 12.6:1 you should achieve your target. Often there is a little bit of back and forth with this technique but using the calculation will get you close in one attempt. From there you can make fine trims as required.

I think there is a small mistake on the maths here, as 11.8 + 7% or 11.8 x 0.07 +11.8 will result in 12.6

I also want to mention that the have over want rule, based on my experience always overshoot your target because of the background compensations + calculation that your ecu does but as Andre said its a nice big "safe" step close to your parking spot.

Thanks chipset! Not sure how I managed to mess up that calculation - I'll put it down to 'fat fingers'! I've corrected my original post :)