Part VI - Tech - Power Trip - 559 HP 550 TQ

Hartline Performance has created several upgrades for the XFI box. One is a plug and play fuel and oil pressure logging kit, which gets its signals through the factory EGR plug and displays fuel and oil pressure values in XFI. This is made possible by taking the cover off of the Casper's ECU Adapter Module...

...and enabling the Oil/Fuel option by setting up the internal jumpers. The logging harness simply attaches into the unused EGR connector on the passenger-side of the engine. FAST also offers a fuel/oil logging kit that plugs directly into the XFI harness on other applications.

This program will be nearly complete, as Cal has already determined the timing and air/fuel maps, the system configurations including fuel calc parameters, and sensor calibrations (save for TPS). It will allow the car to start up and run. However, this program will be altered by Cal into two distinct programs: one for street use, and one for race.

Speaking of starting the car, now is the moment of truth: Junior and I do one last check to make sure that everything in the engine bay and cabin are where they should be, then I prime the fuel system and turn the key. IT LIVES! The roller engine clatters to life, then quiets down as it settles into a high idle and I check the oil and fuel pressure. Since the start up program has a 950-rpm idle programmed in, we'll have to adjust the idle screw to get the IAC in the proper position (between 10 to 20 in Park, warmed up).

We go to View-Idle Functions-Throttle Follower. There's a floating ball that floats based on IAC position. If you want to idle at 950 rpm, and the throttle blades are too far closed, the IAC will be too far open to control that idle (and if blades are all the way open, the IAC would have to be all the way closed to make it idle right). The ball is lowered down into approximately the 13 to 26 range (the range where IAC has lots of control) by adjusting the throttle screw on the throttle body. The idle stabilizes at 950.

I turn the car off. Next, TPS sensor calibration is set (View-System Configuration-Sensor Calibration-TPS Calibration). This will set a scale; there are seven points along the X-axis denoting low and high voltage-low when you don't have any throttle, getting higher all the way to WOT. I need to find the voltage range of the TPS. My TPS had a low range of .57 and a high range of 4.10. Cal subtracts the low from the high, then divides that number by seven to figure the approximate distance between each point. (4.10 - .57 = 3.53 / 7 = .504). Run the arrow over the X-axis numbers and it turns into a hand, then the numbers can be changed manually, making each equidistant from the other.

At this point the car is warmed up and the VE table (F3 shortcut) is tuned for idle-notice that Cal has adjusted this VE table based on my engine, with the lower end at 35 for the mild roller cam, and the high end at 249. Every car is different; some Buicks with big cams and no vacuum might have a low value of 60. Cal tunes the lower left-hand corner group of cells as lean as possible with the car still smoothly running. One trick he uses is to adjust the kPa scale on the lower end to have a value equal to the idle kPa-so the green floating ball (current cell in use-here idling between two cells) is only in one cell. Also, hit F5 to adjust the injector opening retard-it can be adjusted for the best idle possible as well (mine is set at 20).

There are two main parameters that determine how well a car starts: one is cranking fuel, the other is starting IAC position. During the course of the tuning session, the cranking fuel parameters are adjusted during various coolant temperature levels. (View-Cranking/Afterstart Fuel Tables-Cranking Fuel Table).

IAC position is adjusted by accessing View-Idle Functions-Starting IAC Pos vs. Coolant Temp. Like all of these 2D green-line screens, there are two ways to adjust them: (1) grab the line with the mouse and move (not accurate); and (2) click on the line, and use the up/down arrow to make minor adjustments (this is the one Cal recommends).