LS1 tach wire on F-body vs. GTO
LS1 tach wire on F-body vs. GTO 
08-29-2012, 09:09 PM
#4
Same config in file but may need a pullup resistor. If tach is functional but inaccurate read below.
Found this from an email or post somewhere:
Calibrating the tach signal to work for a 8 cylinder tach is fair easy to do, but difficult to be accurate with.
Anyway, you need to enter 12 into two parameters.
With a value of 6 (stock) it takes two 24x ref pulses to transition the Tach ouput high to low or low to high. You need to make it happen on every reference pulse so set it to 12.
For 2 pulses, use N= 6 <-- Stock
For 1 pulse, use N=12 <-- 8 cyl tach
You may need to set it to 3 if these changes make it read incorrectly.
You will have to fudge with these numbers to get it accurate, 11.77 or 12.15 etc. When pops and I did mine it was pretty much accurate below 4k rpm. The accuracy got worse the higher the RPM got. I eventually installed an autometer gauge, set it to 4 cyl mode and set the values back to stock so my gauge would be accurate throughout the entire range.
Found this from an email or post somewhere:
Calibrating the tach signal to work for a 8 cylinder tach is fair easy to do, but difficult to be accurate with.
Anyway, you need to enter 12 into two parameters.
With a value of 6 (stock) it takes two 24x ref pulses to transition the Tach ouput high to low or low to high. You need to make it happen on every reference pulse so set it to 12.
For 2 pulses, use N= 6 <-- Stock
For 1 pulse, use N=12 <-- 8 cyl tach
You may need to set it to 3 if these changes make it read incorrectly.
You will have to fudge with these numbers to get it accurate, 11.77 or 12.15 etc. When pops and I did mine it was pretty much accurate below 4k rpm. The accuracy got worse the higher the RPM got. I eventually installed an autometer gauge, set it to 4 cyl mode and set the values back to stock so my gauge would be accurate throughout the entire range.
