Hello ALL, I'm starting to tune with S_AUJPV4A when compared to a normal AUJP bin with a $8D 730 ECM. I have a pretty built 383 that I spin high. My question is when revving to about 7000 rpm's is the RPM/31.25 hard coded and used for all calculations (PE and other tables) or is it when I only switch to the extended PE table in S_AUJPV4. I'm noticing my tach is not that accurate above 6500 (+- about 200-300 rpms off), shift light isn't always quite the same (it's set to 6800rpm) and my digital ignition box is hitting the limiter before I actually reach the RPM setting, using a MSD Digital7 Plus. I read through some posts that due to errors in upper RPM's the "RPM/31.25" used for calculations in S_AUJP V4A is more accurate to use. I plan on adding Nitrous, but I want to get the RPM's as accurate as possible, so when I add my nitrous RPM window switch (3800-6800 rpm) it will be accurate. Any info is greatly appreciated.
Thanks,
Sal

 

the 31.25 is hardcoded to allow for a higher scale factor on the RPM.
It is used selectively on the display and high RPM tables that have been added to V4 bin.
As far as the accurracy, bench tests with "good" signals tracks well although I don't have concrete values to state.
The quality of the pickup signal is important because RPM is calculated against the ECM clock rate.
You could hit the limiter before you see it on a mechanical tach because it is a time based calculation of rate and filtering of the signal at the tach would be different than the ECM.

 

I tested the 8D SAUJP_V4 while data logging through my wideband and I am happy to say that it IS MUCH MORE STABLE. The RPM's climb normally and doesnt skip up and down like the datalog from my standard XDF file I was using. The car is also cleaner revving, its like music to my ears , the RPM's dont struggle above 6500. I appreciate the technical explanation, It helps me to understand why its better to run the SAUJP_V4

So a BIG THANK YOU for your help on the SAUJP_V4 CREATION!
CAR IS DOING MUCH BETTER!