tach vs scanmaster

[hoser]

I have had very little time this summer to tune and play with the TTA but what i noticed today while cruising to work is that the factory tach and scanmaster to dot agree with each other. The scanmaster reads about 400 to 500 rpm higher. Has anybody else noticed or ran into this ? Without the scanmaster hooked up, the tack looks and acts normal. I assume the scanmaster is correct and the gauge is off. Good news is that the convertor has about a 2800 RPM stall not 2300 so I can go larger on the turbo.

 

[robert lee]

I have had very little time this summer to tune and play with the TTA but what i noticed today while cruising to work is that the factory tach and scanmaster to dot agree with each other. The scanmaster reads about 400 to 500 rpm higher. Has anybody else noticed or ran into this ? Without the scanmaster hooked up, the tack looks and acts normal. I assume the scanmaster is correct and the gauge is off. Good news is that the convertor has about a 2800 RPM stall not 2300 so I can go larger on the turbo.

My guess is the tach is off and the SM is right...