Custom ECU Calibration: HP Tuners & EFILive

Custom programming is always necessary when installing an LS-Series engine in a stand-alone application. In the very least, the Vehicle Anti-Theft System (VATS) must be turned off so that the ECU (Gen III PCM or Gen IV ECM) will command the fuel injectors to pulse. Beyond that, the ECU's OBD-II system will set a long list of Diagnostic Trouble Codes, or DTCs, because an LS engine conversion never involves the same emissions (and non-emissions) equipment as was found in the original vehicle the ECU was pulled from.

Screenshot of [ECM] 12600 - Main Spark vs. Aimass vs. RPM Open Throttle, High Octane

The first step in preparing an engine's ECU for stand-alone operation is to consider the equipment being used (throttle system, transmission type, electric fan(s), etc) and then flash the ECU with a base calibration from a GM vehicle that is a best match. Gen III PCMs can receive a "full flash" using EFILive or HP Tuners to apply a base calibration from a similarly equipped production vehicle. Gen IV ECMs can only receive a base calibration from GM's Service Programming System, or SPS.

Once an appropriate base calibration is loaded in the ECU, the following changes should be made prior to initial start:

  • VATS must be disabled to enable fuel delivery.
  • Disable any non-relevant emissions equipment. It's recommended you speak with your local emissions testing facility to understand the laws as they apply to your vehicle's year/make/model.
  • Update the fuel injector flow rate table according to the fuel pressure regulator type (vacuum or non-vacuum referenced) and fuel injector flow rate.
  • Update the speedometer settings with gear ratio, tire size, and VSS reluctor pulse count.
  • Update spark and fuel tables appropriately. You may need to consult a professional tuner.

The initial engine start will reveal a list of stored DTCs that may need to be disabled if they are not relevant. These can easily be managed (turned off or not reported) after the first several engine starts and road testing.

The two leading tuning packages for LS-Series PCMs, ECMs, and TCMs, are made available by HP Tuners and EFILive. For the scope of LS-Series tuning, either software/interface package will accomplish the calibration changes necessary for a successful LS engine and transmission swap. In rare circumstances, one software package may offer a feature that the other doesn't. HP Tuners VCM Suite and EFILive Scan & Tune have been leading the way since the early days of LS engine conversions. Other than licensing considerations, the systems are highly comparable to each other.

ECU tuning is a process that should be performed in a controlled environment (like on a chassis dynamometer) and with proper diagnostic equipment (like a wideband O2 sensor). Attempting to tune your vehicle on public roads can be dangerous and/or an illegal activity.

EFILive FlashScan V3 see www.efilive.com
HP Tuners MPVI2+ see www.hptuners.com