HP Tuners' (www.hptuners.com ) computer interface, VCM Suite Pro, has a software suite that includes the VCM Scanner and Editor with a few optional capabilities sold as add-ons. The VCM Editor's Flash utility allows the user to read the VCM/PCM flash memory and save it to his computer. The Flash utility also allows a valid calibration to be written to the VCM/PCM, which is ultimately the point of modifying the saved binary image parameters such as spark, fuel, rpm limits, fan-activation temps, transmission shift points and pressures, speedometer settings, and more.
The VCM Scanner utility is an OBDII scanning and diagnostic tool. It allows viewing, charting, and logging of diagnostic data in real time via the vehicle OBDII diagnostic data port. It also allows viewing of vehicle diagnostic trouble codes and other vehicle information. Built-in VCM controls are supported, including real-time command fans, closed loop, gear select, timing, air/fuel ratio, and more. This is serious tuning power for an EFI engine. The company's emphasis is on the high-performance market; hence the touting of speed density with 2-and-3-bar mapping. But the software also gives a knowledgeable owner the ability to tune his engine with much more precision than just about any other package on the market.
To explore the possibility of tuning in some mileage, we went to a knowledgeable West Coast race-engine builder and tuner with the request to fine-tune a 2002 Chevy Silverado 5.3-Liter automatic for mileage with this software. What's the basic strategy for tuning for mileage? Advance the ignition timing and trim the fuel. But before making any changes, we needed to record the stock parameters, which is easy to do with this software.
Drive the truck with the scanner utility active to capture what the engine-management system is doing. The amount of data you can review is limited only by your hard drive's capacity. Our tuner reports that he drove to Rialto, California, from his shop in Camarillo, California, (approximately 100 miles one way) and recorded the whole drive.
Test-Drive Procedure
To speed up the tuning process, it's best to drive the truck the way you normally drive. For example, we began by accelerating through all gears, then settled in for high-speed cruising at around 90 mph. We also recorded several minutes of normal speeds on the highway at light load in high gear, then accelerated hard in high gear to simulate passing behavior. If your driving includes hills, be sure to record a run up a grade.
Reading the stock program parameters, our expert realized GM's tuning was conservative, a move it had to make to accommodate the broadest possible driving conditions, including poor fuel quality and hot intake air temperatures. The new software can narrow the range the engine operates in, one that's more suited to improving mileage in the commuter lifestyle of Southern California.