Among the most dominant GEN4 features is its capacity for multiple mapping. While there are perhaps hundreds of scenarios in which this is possible, Meaney offered this by way of explanation. Let’s say we have a turbocharged V8 with a four-speed transmission; with a single map limited to even something as large as a 32x32 grid, there are still resolution limitations when dealing with an engine that can run to 8,500 rpm and boost ranging from 10 to 40 psi.
The GEN4 offers the ability to use a set of five maps per gear. Each set includes the fuel, spark, lambda, individual cylinder spark (ICS), and individual cylinder fuel (ICF) corrections. For turbo cars, another complete set of maps is used just to help bring the engine on boost when the three-step/transbrake is enabled.
Here’s how this works. In First gear, even with the potential for 40 psi of boost, the car can only really use 10 psi before inducing tire spin. The initial 24x24 map encompasses the 0- to 8,500-rpm range and the -15 to 40 psi load range. Once the car shifts into Second gear, Map 2 is enabled. However, its rpm range now could be from 6,000 to 8,500 and the boost range from 10 to 20 psi. By decreasing the range of both the rpm and boost, we still have the 24 break points each, which will now provide much higher resolution and control. The 2,500-rpm span (6,000 to 8,500) is now divided into 24 columns and the 10 psi range (10 to 20 psi) into 24 rows. In Third gear, the boost now traverses between 20 and 30 psi and will use Map 3. Once in Fourth gear, maps offering control between 30 and 40 psi will use Map 4. In each gear, the tuner has the opportunity to adjust within the map with sufficient resolution so that overlapping compromises are a thing of the past.