Quote:
Originally Posted by west coast
So I have had the same problem as Bobby, my data logs for the rpm is very squiggly. I tried almost every thing listed so far and gave up a couple of years ago on this. One thing that I did do was go back to my tach which is a 2 channel with drive line sensor, down loaded it and my logs looked clean on RPM. one thing that was mention by Tom I am going to try. if anybody gets there's fix please post how you did it.
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Jim, I take it you are using the dual sync also?
I have the Autometer playback and the rpm looks better on there only because the frames per sec are much less than the FAST datalog. The tach gets its signal from ignition box, which gets its signal from the FAST ECU, which gets its signal from the distributor that I believe is the cause of the issue. I can see my tach needle start jumping around at higher rpm and when I use the playback feature on the actual tach I can see it as well. Putting a resistor in-line with the tach could fix the needle jump but it will not prevent the ECU from seeing a messy RPM signal which causes erratic timing and fuel decisions. I firmly believe a crank trigger is the only way to go with these aftermarket EFI setups.