How I Tune Fuel Maps / PROM Tuning

[dave w]

I use DataMaster data logging software. http://www.ttspowersystems.com/DataMaster_downloads.html is a list of vehicles supported by DataMaster. The DataMaster is freeware for the first 20 scans.

The image above is a screen shot from both my TunerCats Fuel Map and the DataMaster Histogram. The Histogram shows which Fuel Map cells are rich / lean. The Histogram and Fuel Map cells are mapped by RPM and Vacuum (Kpa). For my example I am using the cell 1200 RPM / 70 Kpa. The cell Statistics for 1200 RPM / 70 Kpa show an average BLM of 136.8 (which is lean). In the TunerCats Fuel map the current fuel map for 1200 RPM / 70 Kpa is 87.1. I use some math to figure the new fuel map. (Current Fuel Map x BLM) / 128 which in this example is (87.1 x 136.8) / 128 = 93.09.

The next step is the change the fuel map for 1200 RPM / 70 Kpa to 93.09 ... correct the other fuel cell that are rich / lean ... save the change and burn the chip.

Drive around some more ... data log some more ... make more changes to the fuel map ... burn another chip. Repeat the Drive - Data Log - Burn Chip- until your happy with the Histogram.

That how I do it.
dave w

After a couple changes to the fuel map my latest results.

 

[Keitha]

I would suggest that you also smooth the adjacent cells to the ones you correct. It is typically not the case that you would have a lower VE at higher Kpa and RPM cell ranges (ie: 1600RPM/70Kpa = 97.7, 2000RPM/70Kpa = 93.8). With higher load and/or RPM you should always be adding more fuel via the VE chart. In other words the VE numbers should always be getting larger as you move down the chart (higher RPM) as well as to the left (higher Kpa).
It looks like you are making progress. Good luck and have fun!