Tach signal 1000 RPM higher than touchscreen.

[Rc 415]

So I got my HP EFI live running my cammed LS1 BMW E30 pretty well. I'm having two problems. First, is my stock gauge cluster reads 1000 RPM higher than what the touchscreen & computer are showing, and it gets almost 2000 off as rpms climb. Is there a way to adjust the settings to fix this? It's a 6 cylinder tachometer. Second, every time I try to update my 3.5" LCD touchscreen to the 4.0.27 firmware, when I cycle the ignition & remove the SD card, the screen just goes black and I have to revert back to the old firmware. Any ideas?

[S2H]

This sounds like a tach signal output problem. The Holley tach output is designed for 8 cylinders.

So you will need to create a custom I/O output, set to PWM+ & RPM Derived.
The X/Y axis in the table don't really mater, just needs to be set to 50% in all cells.
Then you will use the multiplier & divider to get the value you need for your stock tach.

Holley EFI Tier 2 Training Manual: If you want vary the frequency with engine speed, you set the Type to "RPM Derived" and enter either/or a Multiplier or a Divider. This deserves some explanation. If both the Multiplier & Divider parameters are both zero, the output frequency in Hz is equal to the engine speed in RPM. If the engine speed is 1000 RPM, then the output frequency would be 1000 Hz. A 1:1 ratio usually results in a frequency that is too high for most applications. For a one pulse per fire frequency for a V8, you would need a divider of 15. This would result in a 4 pulse/rev. A divider setting of 30 would result in 2 pulses/rev, which happens to be what many GM tachometers use.

The math is basically 120/cylinders.
120/8 = 15
120/6 = 20
120/4 = 30

So for a 6 cylinder tach.
Set Multiplier to 1
Set Divider to 20

[Rc 415]

Thanks I'll give that a try when I have time. As far as the touchscreen, I've updated the ECU before updating the touchscreen, even updated the ECU via touchscreen with SD card. I still have the same issue when updating the touchscreen itself, no matter what I try. Even tried the V3 firmware, does same thing. Only comes back when I boot from SD card with original V2 firmware.

UPDATE: Still having same issue with updating the touchscreen.

[Danny Cabral]

UPDATE: Still having same issue with updating the touchscreen.

Which is displaying RPM incorrectly? Your OEM instrument panel, or the Touchscreen/ECU?
http://forums.holley.com/showthread....7583#post47583 (Tachometer Signal Information)

[Rc 415]

It's definitely the tachometer, as it now reads 3000 RPM in 6th at 80 MPH, where as before, it was at about 1800-2000 RPM at 80 MPH in 6th. So a signal amplifier will work for me? My bigger problem is with the updating issue.

[Danny Cabral]

My bigger problem is with the updating issue.

I don't know why you're having problems updating the 3.5" LCD Touchscreen. The EFI (laptop) software, ECU firmware & Touchscreen, must all be of compatible versions (V2, V3 or V4).