July 21, 2020
Back when I had my 1999 GTP, I quickly ran in to the limitation of modding based on what the PCM (Powertrain Control Module) could accommodate. I used a product called a DHP PowerTuner and it let me tune the car to take best advantage of the installed mods.
In the old days you set the timing by rotating the distributor and you controlled fueling by selecting a certain sized carburetor and then “jetting” or twisting a screwdriver to tune it to run right.
Today we have computers control all that. We use fuel injection and a way more advanced timing systems. We can vary spark and fuel based on RPM, temperature, load and even the kind of fuel used.
In the old days, we used a timing gun to see what the timing was, we used our ear to hear how smooth the idle was and on the more complete tunes, we pushed the gas pedal to the floor and made sure that all butterflies were fully open on the carb(s). Today we have far greater control, but we need a computer, some very specific software and an interface to be able to manage this all.
This is where HPTuners comes in. They’re a company out of Buffalo Grove, Illinois (Chicago area) that make the software and hardware interface that connects to the OBDII connector of your car that lets you connect, read, edit, and write to the computer of your car. In essence, this is the way we tune cars today.
I also used the HPTuner on the GTP, it was a better product, and while the PowerTuner company is now long defunct, HPTuners are a strong, stable company that has grown tremendously over the years. I also have a nice tune on my 2013 Impala. I use it to get a little extra mileage and power from the car, and make the gear changes a little snappier and firmer. I’ve also removed the factory speed limiter.
Yesterday I purchased the necessary credits to be able to tune my Z06, and one of the first things that I did was read/save the file from the PCM. I was surprised at how small the file was in comparison to the older GTP, and even smaller yet when compared to the 2013 Impala file… we’re talking maybe 1/18th the size! Then again, there are no transmission settings, the ‘Vette is a manual and no supercharger support, too… but still… it’s a tiny file in comparison to (for example) the 8 times larger files that come from the Impala tune!
I’ve not really spent a lot of time tuning a car in many years, and so I plan to be very careful with this process. Mostly I want to tune just to have fun with the car more than any deep-seated need to extract the last ounce of power from it. I’d also like it to do a bit better mileage, not that it’s that important. There is a guy on YouTube with a base C5 that can pull 40 mpg from his car… I doubt mine could ever do that, as the gearing is not quite the same, but it would be fun to play and see how close I could come. The concept of a “hyper-miler” performance car running lean safely is very interesting to me.
I have the laptop, interface and licensing all done, but I am still missing a wideband O2 and gauge, which I will add at a later date before I get too deep in to the tuning. Right now I want to learn about the car, do a lot of scanning and see where it sits. I was especially happy to learn that the ‘Vette has a 100% stock file in it and has been untouched in that sense.
Here are some YouTube videos that talk about using the HPTuner, tuning in general and specifically tuning the GEN 3 LS6 engines:
The Goat Rope HPTuners 101 series:
More to come later!