The ever-increasing number of “do-it-yourself” horsepower enthusiasts helped to explode the market for standalone EFI systems. These self-contained systems are designed to work independently from any other vehicle systems. This means they work equally well in a classic restoration project, dedicated racecar, or retrofit to most modern road-going vehicles. Almost all stand-alone aftermarket systems are […]

GM PCMs used in the early TPI systems were a simple MAF based, bank-to-bank system. Early LT1 systems were speed density with sequential control with knock control. The LT1, 3800 V-6, and LS1 are primarily MAF based, sequential injection with knock control. For LT1, spark is calculated in terms of MAP, just like speed density. […]

The Ford Mustang is arguably the most popular vehicle for the do-it-yourself tuner. Ford refers to its PCM as an EEC, or electronic engine control. Starting with the 1988 California specification, and 1989 50-state versions, the Mustang has been equipped with a mass air, sequential EFI system. Other truck and passenger car applications soon followed […]

So far, the focus of this book has been naturally aspirated engine calibration. Although forced induction has been occasionally mentioned, it deserves some more focused attention. The aftermarket performance industry is flush with ways to add power to an engine. Few of these methods come close to the potential that forced induction offers for power […]

At this point, most of the work is complete. If all the steady state values are correct, the vehicle should operate fairly well. The final phase of calibration is improving drivability. This should be thought of as finely polishing a sculpture. Where we were using a chainsaw earlier, we are now using sandpaper. There shouldn’t […]

Now that the engine has been mapped under most stable operating conditions, it is possible to move on to a less stable condition: idle. Because of the slow engine speed, there is a relatively long time between possible corrections the PCM can make at each TDC event. The longer pause before the next feedback signal […]

Now that we have a good idea of what an engine needs to operate smoothly, it is time to actually begin to construct the framework of the calibration. Before the engine is even started, the calibrator must provide the PCM with some parameters that are close enough to the optimum setting to begin checking operation. […]

Before we begin changing PCM parameters, let’s take a look at the key elements to monitor. Most tables and functions in the PCM are constructed with axes that represent a range of engine operating conditions. In order to know where to make changes to the PCM tables, it is necessary to know exact engine conditions […]

Knowing that engines produce power by harnessing the dramatic pressure increases resulting from the ignition of the air/fuel mix, let’s take a look at how that pressure plays into the calibration requirements. Cylinder pressure is directly related to engine efficiency and output. Engineers often refer to BMEP, or brake mean effective pressure, to describe engine […]

Now that the inputs to the computer have been covered, it’s time to look at what the outputs can do. Not that many outputs are required to operate most engines. The advantage of EFI is the ability to very precisely control each of these outputs. Think of jet changes in a carburetor as strokes with […]