Tach Issue (Turbo Timer Shows Different RPM than dash Tach)

[rico05]

HKS E-01 timer shows a pretty big difference in engine RPM from the dash tach. Tach shows 1500 at idle, E-01 shows 1650. At 4k on the Tach, E-01 shows ~4500RPM. Which is the correct one? Any idea why this is happening?

[rico05]

Anyone?

[CA19DET]

my haltech shows rthat my tach is off by about 400-500rpm, and that it cant keep up when driving and i hit boosta nd the cams kick in...

[rico05]

So is the tach or the E-01 correct? I guess that is my main question.

[CA19DET]

seeing that the tach was a generic part and it is old, i would go by the E-01 (other may view this different) but i think the sensor is newer and more accurate in the new E-01.. i trust my haltech and will be setting up my shift light by the revs on the haltech (if the haltech says 7800 and the tach says 8300 i'l going by the Hlatech figure, and set the light to that, i was told to get a autometer tach or some aftermarket race tach that can read more accurately and quicker, but i hate them, and jsut want the shift light with the RPM pills)

[boost_boy]

HKS E-01 timer shows a pretty big difference in engine RPM from the dash tach. Tach shows 1500 at idle, E-01 shows 1650. At 4k on the Tach, E-01 shows ~4500RPM. Which is the correct one? Any idea why this is happening?

Always reference tach signals down the middle between two different tachometers. They all won't be the same and analog tach seem to get out of calibiration after so many years of use.

Dee