Fast xfi rpm issue

[jamie2370]

Originally Posted by Signman

Have you tried the tack output in the XFI harness if I recall is the white points wire

That's what is firing the msd box. Seems the more people I talk to I am thinking it's a tach issue. Nobody seems to have this problem. And a Tach is a necessity in Stock. Foot brake, and reverse pattern ATI 350 means it's all on me lol

[Ernie Neal]

I have used a digital hand held tach that uses a small piece of reflective tape on the damper to verify which is correct.
Ernie Neal
SS 354

[Signman]

Originally Posted by jamie2370

That's what is firing the msd box. Seems the more people I talk to I am thinking it's a tach issue. Nobody seems to have this problem. And a Tach is a necessity in Stock. Foot brake, and reverse pattern ATI 350 means it's all on me lol

My car is in mothballs in the trailer so can't check without standing on my head. In a couple months will have a much better situation.
Believe you have the right set up. Don't expect the RPMs to match exactly a tach really is a volt meter depending on the quality of the device there may be inaccuracy. Plus there is noise that is tough to get rid of mostly from the MSD the 7AL2 is really bad tons of RF. If you wish to try to arrest some of it set up a Faraday shield around the box with aluminum expanded metal and ground it.
You should probably try a different tach again don't expect them to match exactly but they should be close enough that your staging and shift RPMs on the data log should make sense.