Tach output adjustment?

[mattheripper]

Seems like like output errors are not much of a problem according to this forum. However I was wondering if it is at all possible to write something in the code so we can offset the tach output however much is needed so the tach in the gauge cluster will read true. Know that I write this in complete ignorance to how complicated or impossible it is, only because I am very much a newb to electronics for the most part. I'd like to learn about writing code etc. though.
There is just one other guy on here that the search function lead me to and his was only 200rpm off so he ended up just living with it.
My problem was with swapping from a 6cyl to a 4cyl, the r32 gauge cluster was originally 1000rpm off either way whether I did half speed or normal in the tach out options in tunerstudio IIRC. I called Matt Cramer to see if there was a software solution, kinda like what I first asked in this post, and he informed me there wasn't. So I did the reverse of what ka24de->rb20det swap people do and put the s13 tach module in my Skyline gauge cluster. But now I'm still 500rpm out lol.
So I'm just wondering if as well as normal or half speed functions if it would be possible to get another adjustment in the speed option that we could manually figure out whether 1/4 speed, 5/8 speed or like 1.25 etc. is needed, maybe a box thats a multiplier is what I'm imagining? If I'm way out of line here let me know haha but it does seem half possible. Thanks for everything Phil. Also shout out to Matt for constantly answering my extremely beginner questions. Megasquirt in general has definitely expanded my knowledge and for that I'm super grateful. Other than little things like this I can boast about how well it runs now, so a thank you to everyone involved that really made this diy-able.

P.S. Since putting in the s13 tach I have yet to try changing it to half speed to see if that works. However all the s13 guys on ka-t.org are using normal, and that is what I left it at before switching tachs. Next time I got the laptop I'll check that and report back. Thanks again.

[slow_hemi6]

Why don't you just get your S13 tach calibrated by an instrumentation tech.

[mattheripper]

Okay:) What do they do for curiosity? I checked and it looks like there is some in the area.
Still would rather the other route if its ever going to be possible. That way it would help a few on us
with this problem as I'm pretty sure me and the other guy are just the only people who have
posted about the problem with our stock tachs. So I'd rather pass the bucks on to Phil for
developing some then pay a instrumentation tech just for me, to be honest.
But yeah to simply answer your question I did not know there was such a thing.

Why don't you just get your S13 tach calibrated by an instrumentation tech.

[LT401Vette]

So I'd rather pass the bucks on to Phil for
developing some then pay a instrumentation tech just for me, to be honest.

This would need to be implemented in firmware.

[DaveEFI]

Many OEM tachs ain't that accurate anyway. The makers manual for my car cautions against using it for anything that requires you to know the true RPM - says use an external accurate unit.

[mattheripper]

This would need to be implemented in firmware.

Oh okay. Yeah that seems even more difficult then. Thank you for your reply.

Many OEM tachs ain't that accurate anyway. The makers manual for my car cautions against using it for anything that requires you to know the true RPM - says use an external accurate unit.

Yeah may have to do that. Thank you.