Wiring an MSD 8913 tach adapter: RB25det S14

[Flatline1121]

So the tach output on my RB ecu is fubar. as is a few other things but thats neither here nor there.

I wired up an MSD 8913 adapter to it for a tach signal. Right now its wired to the coil supply 12v wire as it states in manual. Only i have it wired in the cabin close to the ECU. Tach works, but it seems to be off if my ears serve me right. Like it reads high. im new to the engine so im not familiar to how it acts. Is seems to idle high (around 1500) with the IACV screw 2.5 turns out from all the way tight (the way you set an sr20 to standard) but i dont know if thats a correct procedure.

Anyone with experience in this?
Does the tach still need to be adjusted like i keep reading people have to do?
would it be better to wire it closer to the coil packs to get a better reading? Electrically it shouldn't matter because the module reads current draw through it which shouldn't change, but i like to cover my bases. Also, would the tach out from the 8913 be good to use for an SAFC to monitor?

TIA for any input. Ill post back if i find anything out.

[240z4u]

The stock tach is a 4cyl tach, the readings will be off. You can adjust for it, but it will never be "perfect". I set mine up to be correct at redline and pretty much ignore it otherwise.

[Flatline1121]

Thanks. Ill adjust it and see how it does. I know for sure its off now as my alt doesntwant to charge off the field wire so i have to rev it up to 2k to force it to charge. But the tach reads around 3k before it does that.

Ill work on adjusting it and see what happens.

[240z4u]

If you have to rev it to get it to charge, you've got some other problems lingering FYI.

[Flatline1121]

Well aware of that actually. Just had the alt repaired because it wouldnt charge o its own with 12v from the field wire and when it did charge, it was pushing 18v out.

This time around im not positivenon what the issue is, but it could be numerous things. Old battery or even a bad ground at the battery or the alt. Could even be the alt going bad again.

[240z4u]

It's always something!