Build Turbo Kits

Learn How To Build Turbo Kits

Chapter 8 - PCM Tuning

A proper PCM tune is essential for turbocharged engines. Without it, you will surely grenade the engine shortly after boosting it. During tuning, the AFR and timing curve are set to create the most power while preventing detonation. The details of the different tables and parameters that are edited during tuning are beyond the scope of this guide. This guide will provide you with different tuning options to consider for your engine.

Dyno Tune

A dyno is by far the best way to have your car tuned. While on the dyno, your car is in a controlled environment, enabling fine adjustments to be made quickly and easily. An experienced tuner familiar with forced induction can pull every ounce of horsepower and torque from your engine while keeping it from detonating.

Mail Order Tune

With a mail order tune, you send your car’s PCM to a tuner, and they load a customized file to it. You let them know what modifications are done to your engine, and they program the PCM to work with those modifications. The problem with a mail order tune is that the programmer has no feedback from your car’s sensors, so you are not really sure that the tune is spot on. The AFR could be off, and the timing curve may not be right. Your engine may not be putting out its full potential, or worse case, may be running too lean with too much timing. If you opt for a mail order tune, you should at least run a wideband to monitor your AFR.

Do It Yourself

There are many different tools you can purchase to do your own tuning. If you are already a tuning wizard, or are willing to take the time to learn the fine points of tuning, it may be worth your while to purchase one of these products.

The benefits are being able to change your tune as needed, such as when increasing boost, or changing to a more aggressive cam etc. These tools include simple hand-held programmers, PC software, piggy-back computers and full blown standalone fuel injection systems.

Hand Held Tuners

A hand-held tuner plugs into your car’s OBDII port and communicates with the PCM. One such tuner is the DiabloSport Predator. It will enable you to add and subtract fuel and timing up to 20%. This is often not enough control over your PCM for a turbocharger.

The Predator also allows for a custom tune to be uploaded to your PCM. You can download your PCM’s binary image and email it to a custom tuner. They will modify the program to suit your needs and email it back to you. You can load the new program to your PCM via the hand-held tuner.

Unless you are using a hand-held programmer to load a customized program to your PCM such as with the DiabloSport Predator, it is best to spend the extra money and buy true PCM programming software. Most hand-helds to not allow for enough fuel and timing adjustments to suit the needs of forced induction.

PCM Programming Software

PCM programming software installs on a PC or laptop and enables you to edit tables and parameters in your PCM. Most of these products allow you total control over fuel, timing and other tables in your PCM.

Some of the more popular software suits are listed below.

HPTuners VCM Suite for GM Cars

The VCM Suite by HPTuners includes PCM editing software and a scanner that enables you to log data in real-time. The logged data will enable you to make informed decisions when making adjustments rather than guessing.

The editor allows you to adjust hundreds of parameters, allowing you to tune for tubocharged applications. Among the editable tables and parameters are injectors, MAF table, power enrichment, closed/open loop characteristics, timing, rev limiters, speedometer, shift speeds and firmness, speed limiters and so on. The VCM Suite also allows you to run in speed density mode, removing the MAF from the engine management system. More on speed density later.

EFILive FlashScan

FlashScan includes a scanner and tuning software like the VCM Suite. It allows you to tune and edit hundreds of parameters, log data in real-time, and also run in speed density mode.

Hondata S200/K-Pro for Honda Vehicles

Hondata offers tuning and scanning tools for Honda vehicles. You can adjust timing and fuel parameters for turbocharged applications.

Sniper Special Forces and Commando Tuning Software

Sniper offers tuning software for 1988 to current Ford vehicles. You can tune fuel spark and many other parameters with Sniper products.

Standalone Systems

A standalone system replaces your vehicle’s stock PCM. The new PCM is a programmable module that allows you to enter custom tuning values for hundreds of parameters. Standalones usually come complete with a PCM, wiring harness and tuning software and run as speed density systems.

AEM PEMS

The AEM Plug and Play Engine Management System is a direct replacement for your stock computer. It uses the stock wiring harness and allows you to tune your engine with the included software.

BigStuff3 Gen III Pro SEFI

The GenIII Pro from BigStuff3 comes ready to plug and play for some cars. Other cars will require some customization to the wiring harness. The Gen III Pro comes with two wideband O2 sensors for accurate control of AFR. It allows for real-time editing and monitoring of engine management controls.

Other standalones include Accel DFI and FAST XFI. In order to run these systems, some customization may need to be done to run correctly.

MegaSquirt

The MegaSquirt is a low-cost, resource-free, do it yourself fuel injection system. You have the option of buying it in kit form, or pre-built modules. The MegaSquirt is fully programmable via free software and can run 4 – 12 cylinder engines. The installation is easy, and so is the programming.

The latest versions of MegaSquirt can also control ignition and include an EDIS controller. Some sort of crank trigger may need to be used to be compatible with some engines.

Piggyback Systems

Greddy e-Manage System.

A true piggyback system that allows you to keep your stock computer. The e-Manage system lets you adjust fuel and timing maps for fine tuning your engine. The unit taps into most Japanese wiring harnesses and lets you use the existing sensors.

Greddy also offers the e-Manage Ultimate and V-Manage for VTEC engines.

APEXi AFC NEO

The AFC NEO is a piggyback fuel controller that enables you to adjust air map, throttle point and more. The unit also lets you monitor air flow %, RPM, battery voltage and more.

UNIchip Performance Computer Module

Unichip offers a programmable piggyback module that communicates with your factory computer. You can adjust timing, fuel and other parameters that affect your vehicle’s performance.

Unichip is available as a plug and play application for cars and trucks from Dodge, Ford, Toyota, Scion, Nissan, Mazda, Infinity and more.