HP Tuners - Part II - Change the Tachometer RPM output to an 8 cylinder V8.
OK, so she's running however if you hooked up your stock Tach or your after market Tach it most likely aint reading right, what did you do wrong? Well, most likely nothing, you see the PCM by default is putting out a tach signal suited for a four banger and not a V8, so let's fix that. I am not going to go into the science of how this works (24 tooth reluctor wheel, blah blah blah) just use this cheat sheet:
for 4 cylinders set it to: 6
for 6 cylinders set it to: 4
for 8 cylinders set it to: 3
Assuming you completed Part I and disabled your VATS already:
1. This time we start in the comfort of your own home, fire up your laptop and launch the Editor. Open the file we saved in Step 3 of Part I. (Now this is your new base file, assuming that it all worked last time).
2. Make changes in the Editor, we will make one simple change, we need to change the Tach signal from the number 6 to the number 3 (notice I did not say cylinders) We do this in the Engine menu, General tab, Tach Output section. Change both "Resolution" values to:
Resolution - High 3
Resolution - Low 3
[pause for mini rant] this is what I was talking about in Part I, proper developers would mask this insanity with an option that says Number of Cylinder: (had they done it, this post would not exist, lol) [unpause]
3. save the changes you made to a new file and call it something like "02 - VATS Disabled V8 Tach Signal"
4. now get in your truck, hook up your HP Tuner to the OBDII port and then your USB cable to your laptop, turn the key to the ON position, launch the Editor program, this time however you DON'T have to read the information / configuration from the PCM into your laptop because it is already there, after all it came from the laptop where we made changes last time and that same data was written to the PCM, so now just write the new changes to the PCM.
Note:
sometimes you have to write the entire tune file to the PCM, sometimes it is perfectly happy with only writing what's changed, more on this later.
More words with each pic:
In Part III we will cover changing Tire Size and Gear Ratio