Re: Upgrades?????
I'll add my 2 cents.
The PCMs aren't chipped they are flashed through the diagnostic connector.
1) There are two areas to improve power: fuel and timing.
Timing - The PCM uses two 2D tables of data for timing - a high octane table and a low octane table. The tables provide the timing based on RPM and cylinder airmass (g/cyl). You can add timing where ever you want/feel. Optiminal timing improves both power and fuel utilization (fuel economy). These tables are optimized based on the octane fuel you want to use.
Fuel - There is a part throttle A/F ratio set at 14.7:1 to minimize emissions and improve fuel ecomony. During WOT (wide open throttle) there is another table that essentially provides the A/F ratio as a function of RPM. At high RPMs the stock WOT A/F is set at 11.3:1. To make better power and use less fuel you want this A/F to be about 12.5:1 for this type of vehicle.
2) Auto tranny shift points - There are tables that show at what speed to upshift and downshift as a function of throttle position. I have mine set up so that when you are just putting around the tranny upshifts sooner than stock to improve fuel economy. When you give it some throttle I have my tranny shift at higher speeds to improve acceleration. Properly picking tranny shift speeds can improve MPG.
3) Shift firmness is comprised of two elements: torque management and shift pressure. Torque managment is basically the reduction of timing when shifting to minimize the load on the drivetrain. Shift pressure is kinda how hard the tranny shifts gears. Increasing shift pressure doesn't necessarily reduce tranny life.
4) VVT - The PCM uses 5 VE (volumetric efficiency) tables to accomodate the VVT. My opinion why the 3.5L torque curve is flat is that the engine runs out of air at the upper RPMs. The 3.7L with VVT has its peak torque much higher than the 3.5L.
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