I have an autometer digital RPM gauge wired to the (-) terminal of the trailing coil. and a S5 TII (JDM if it matters) cluster with a S5 NA RPM (9k rpm).

at idle, they are pretty close to the same. but the higher i go in RPM's, the more they differ. The stock dash being higher.

example: (not exact numbers, its just to give you an idea of whats going on)

stock dash is at: 2k
autometer digital is at: 1800
-------------------------------------
stock dash is at: 3k
autometer digital is at: 2600
-------------------------------------
stock dash is at: 4k
autometer digital is at: 3400

wich one would you trust? just from the sound of the motor, im guessing the autometer one is correct. and is what im following right now.

 

Are you running different wheels/tires then stock sizes?

 

yes, but that only effects the MPH not the RPM.

 

Right. Duh. Huge brain fart there.

Maybe find a timing light with an RPM readout?

 

well, multimeters that read RPM connect to the spark plug wires. Just like for dyno RPM read out. And my guage is hooked to my trailing coil... So this also makes me think the gauge is correct and the tach is off.

I think the problem is i switched from the turbo 8k tack to the NA 9k tach, the calibration is off...

anyone else have this problem?

 

Just run it till the rev limiter hits, one of them better be accurate to whatever the redline is.