Tachometer

[blueman803]

Where does the gauge get its signal for RPMS? Does it come from the ecu or is there another source? And what is normal operating temp?

 

[steve]

On the DOHC 4G63, both generations, the tachometer signal comes from the tachometer gate. Both the meter and the ECU use the signal. On 91-99 cars it comes from the power transistor module. On '90 cars it comes from the tachometer gate on the coil pack.

Steve

 

[blueman803]

I am no longer using the stock ignitor. Does the 90's coil pack depend on the ignitor? Or is a seperate part that generates the signal? Can I just use the 90's coil pack and run the tachometer signal to the 91 tach wire?

 

[steve]

what are you using for spark right now?

Steve

 

[blueman803]

I am using megasquirt, it has internal VB921 transistors to control the coils.

After some searching it appears I could swap out a 90 coil pack to drive the gauge? Would this work? The 90's coil pack creates the rpm signal off of the actual coil, where as the 91-94 uses the ignitor to create the signal? So I can get the noise filter and use a 90's coil to drive the gauge?