At EFI University, we often find ourselves trying to help folks understand the differences between racecars and OEM vehicles that have been modified for more performance. The discussion often boils down the similarities and differences between the skills required to accomplish either job.
A lot of self proclaimed tuning experts on the internet today have rarely, (if ever) participated in any actual engine development work, engine design or blueprinting or even (wait for it….) any actual dyno tuning of an ECU!
Whether they are simply plugging in a cable to an OBD2 port on a stock vehicle or connecting to an aftermarket ECU via a graphical user interface, many of these individuals are simply copying the work of others and calling it their own!
At the professional level, there are some really technical skills and abilities required to accomplish either task well, but today I thought I’d discuss some of the things that might help new tuners understand what they are getting into.
Let’s start with OEM re-flashing. Few products have transformed the automotive industry as much as the advent of flash programmable ECU’s in modern vehicles. These devices hold all of the calibration data required to make you engine run under a myriad of circumstances and a sharp tuner knows that most of the time, once changes have been made to the engine, they’ll need to modify the data stored in theses tables.
The challenge becomes knowing which tables are being actively used and are controlling the engine’s performance at any given time. You see, typically an OEM manufacturer must contend with hundreds of operating conditions and variables from hot to cold, wet to dry, high to low and everything in between. Each group of engineers responsible for this task must come up with their own software solution for how to deal with the problems of an engine that doesn’t operate in one location all the time.
Typically, this requires hundreds of tables to cover every conceivable combination of scenarios a driver might encounter, even though many of them might never even get used by a particular driver’s habits.
For example, a driver of a Subaru outback in Alaska might have to contend with the extremes of temperature swings, and large changes in altitudes as they drives in mountainous terrain in summer or winter conditions. They expect their ECU to properly control the engine without the need to stop and relearn anything, or perform any resets to the memory, etc. A driver of the same car, who lives in the southwest might only ever drive near sea level in mild, consistent weather patterns, and of course they also expect the vehicle to run well all the time.
Using a combination of raw man-hours of live testing as well as computer modeling and simulation it could take a manufacturer as much as 100,000 hours of development time to build a complete engine calibration for a single vehicle within their line up!
So, what happens when we modify the engine configuration with aftermarket parts? We need to change the calibration data stored in the ECU memory to match by plugging in with a hardware interface and a software package that allows us to read the data currently stored, modify it, save it to a new file and then upload that new file to the memory, by “Flashing” it into the memory of the computer.
To do this successfully requires someone with great computer skills, and a working knowledge of the sensor behaviors and actuators controlled by the ECU. An absolute understanding of these sensors and actuators isn’t necessarily required though, because most of the data won’t be changing from what was already installed, with the exception of possibly fuel injector flow rates and latency times, considering this is typically one of the first upgrades folks make. Mainly, the tuner will be modifying the airflow and spark tables used during normal operation.
Finding and modifying the correct table, with the correct value is typically the biggest challenge tuners face. Its not uncommon for an ECU to have four to six individual maps for controlling spark timing, without a clear indication of exactly which map is being used at a given moment.
Because of this lack of information, tuners must become skilled at reading and interpreting data logged files generated while the engine was running under different conditions. This is an essential skill that is required to become proficient at OEM re-flash tuning. Also, since typically these tables cannot be accessed by the tuner in real-time to make “live” on the fly changes, it is difficult to always get it right on the first try, which means lots of trial and error.
One consequence of tuning in the aftermarket in this fashion is that since most of the vehicles being tuned are the same make and model, tuners do a lot of copy and paste style work to cut down on the amount of time required to complete the job. That’s certainly okay to do for some areas that are consistent across the board, but in other ways it completely negates the whole object of a custom tune in the first place. Then, after the engine succeeds in making a little extra power, the tuner pounds their chest as if they were a miracle-working evangelist on a mission to redeem the sinners of the world and without their tuning prowess we’d all be relegated to the dark ages. They forget, of course, that thousands of hours of someone else’s labor had to exist long before they ever got the ability to even have tools to plug in, download a file and make a few quick changes! For example: Who calibrated the scaling for the air and water temperature sensors? Who wrote the algorithms to calculate the airflow models used to determine fuel flow and injection times based on the values a tuner will later modify in the tables? Who installed the wiring harness that connects each sensor in the proper location for the ECU to interpret them?
These are just a few examples of what the hard working engineers at every OEM manufacturer have to do every day in order to make life for the rest of us easier! Its also a good example of the skill required to convert a carbureted engine over to a full stand alone aftermarket racing ECU!
At EFI University, we talk about EFI systems consisting of three major categories:
In order for an engine to run well with EFI a wiring loom that fits the engine correctly, and connects the individual sensors and actuators to their respective locations at the ECU must first be constructed and installed. Careful attention must be paid to wiring sizes, current demands, crimped connections, and power or ground supplies, otherwise the quality of the system is compromised and the ability to run well is in jeopardy before we even begin.
Once the proper connections have been made, a configuration must be created that allows the computer to correctly identify each sensor, each injector or ignition coil and any other output the engine might have such as nitrous or boost controllers. Because most aftermarket computers are capable of controlling a wide variety of engine styles, one must be sure it is set up properly to handle each device.
Lastly, we get to the calibration. This is the part we get to skip directly to if we were tuning an OEM vehicle with an aftermarket re-flash tool. This step requires the tuner to input variables in tables that describe the engine’s fuel and spark requirements. Typically, the best way to find the correct values is by testing and gathering data on a dynamometer and making the required changes to the file in real time, or “live” tuning.
At the end of it all, a lot of the skill required cross over between live tuning and logger data tuning, and a successful tuner will need to have both skill sets. Neither job is what I’d call “easy”, and while decent results can often be gained by many attempts at trial and error, it’s best to find a professional tuner who is well versed in the type of tuning you require and let the guide you through the process in order to avoid a lot of the common pitfalls each method presents.
In any case, the more you know the less mistakes you’ll make so whether you are dealing with stand alone racing ecu’s or OEM reflash tools, don’t forget to read the user’s manual! See ya next time!