Adjustable Tach Output Frequency?

[shaodome]

I know there was the half speed option for the tacho output, but I was wondering have you guys considered expanding on that? For example:

There are a lot of nissan 240sx cars running with either 2jz,1jz,Rb25, and LS1 swaps now. Originally the cluster was designed for 4cyl applications so without the use of a tach adapter the RPM reading is off.

Thoughts?

[jsmcortina]

I've an idea how to achieve this, I've added it to the TODO. The present scheme is synchronised to the tach-in which is good. A variable scheme wouldn't be sychronised and _might_ give a wandering indication at very high RPMs.

James

[weeblebiker]

James,
will the "fix" allow for use with crank and cam sensor driving a cop ignition to mimic a single coil distributor ignition to drive a tachometer? ie: 2 pulses per crank revolution/4 pulses per cam revolution on a 4 cylinder?

although couldn't a bit of code be written to give a tacho signal every x degree of the crank trigger wheel, or parallel the ignition output ?
or is there an option already?

I don't know many people who look at the tach at very high rpms, don't let that be a stopper.

[jsmcortina]

James,
will the "fix" allow for use with crank and cam sensor driving a cop ignition to mimic a single coil distributor ignition to drive a tachometer? ie: 2 pulses per crank revolution/4 pulses per cam revolution on a 4 cylinder?

That's what it does already ?!

James

[shaodome]

This addition to the existing code would be more applicable for those users who have an OEM tach and then swap in a different engine that has a different number of cylinders.

[weeblebiker]

pm's you James, don't wanna threadjack

[Peras]

I know there was the half speed option for the tacho output, but I was wondering have you guys considered expanding on that? For example:

There are a lot of nissan 240sx cars running with either 2jz,1jz,Rb25, and LS1 swaps now. Originally the cluster was designed for 4cyl applications so without the use of a tach adapter the RPM reading is off.

Thoughts?

There is an easy way to fix this, and it will only take a couple of minutes.
Take the cluster out, remove the front covers, on the back side of the cluster where the tacho is you'll find three screws. Take those screws out, and take the tacho out.
Now when you look at the PCB on the tacho you'll see holes where the screws goes in - one is ground, one is 12V, and one is signal (everything is marked on the PCB) - connect everything while the tacho is out and run the car (I do this on the bench using the stim - it's more precise). Now let the car RPM settle and take a small flat screwdriver to adjust the trimmer on the back of the tacho (look at the picture attached below). Look at the RPM reading in MS and adjust until you get correct RPM on the tach. Put everything back and your done!
BTW, most tachs I've seen can be adjusted this way.

(sry for the big pics, just rightclick on the image and hit "view image")