I couldnt find the answer on search. Would an aftermarket tach need to be set for 4 cylinder? tx

 

It did on my conversion.

 

why????

 

The tachometer signal for an LSx is an output from the computer and GM decided to make it output a 2 pulse per revolution signal. The standard V8 signal is 4 pulses per rev. 4cyl`s have a standard pulse rate of 2 ppr, so to make a tach work on an LSx you need to either set it to look for a 4cyl signal or reprogram the PCM to have an 8cyl tach output.

 

i never knew that , thanks.

 

Hi,

*sorry bad english*

We put an LS1 in my 75 Corvette with a T56.

Problem:
The Tachometer is original (4 ppr) an the LS1 makes 2 ppr...

Engine runīs with 4000 RPM - the Tachometer tell me 2000 RPM

What must i do to use the original Tachometer?

We found no Parameter (settings) for the 2 ppr/4 ppr...


Thx

Meiko
from Germany

 

If you are handy with electronics you could use a frequency multiplier to convert the signal to 4 pulses per revolution.

 

Hi Jeff,

2 ppr?

My Tachometer needs 4 ppr - or?

Better a multiplier...

Any fixes?


Meiko

 

Thanks, I fixed it.

 

You can convert the signal with this. http://www.dakotadigital.com/index.c...rod/prd127.htm

 

What type of tuning software are you using? I know that EFI Live 7 and HP Tuners have parameters to change the tachometer output.

 

Thanks...

We found the parameter

And it works

 

Can HP tuners reset the tach pulse to work with a vintage car?
(69 Camaro)

If so, how.

I already looked and even searched the help file

Dakota Digital unit is supposed to work for this application (ECM driving older coil driven Tachs But using the ECM to do it directly would be cooler

Thanks