I put a stroked 5.7 in my wife's satellite [sorry,not an a body]. I used the tach signal from the MSD Hemi6 to trigger the FAST EZEFI. How do I hook up the tach? Can I trigger it from the same wire without affecting the efi?
Tach
- Thread starter Mopar Sam
- Start date
-
I am not familiar with this box. I hope that someone can help. Just my thought is that there maybe interference if you connect the two wires. The only thing I have is I used a 6 AL with the Fast and used different wires for the ECU and the tach.
Good luck on your project.
Good luck on your project.
General Disarray
Well-Known Member
Why don't you call the FAST or MSD tech support?
Yeah, I guess that is what I will do.
I hope you are right. I know the EZEFI is sensitive to electronic noise. I was hoping some one on here had already one this. When I find out for sure I will post.
I recently used a oscilloscope to measure the msd tach signal. It's a clean, stable 24% duty cycle square wave. Voltage peak to peak is right with the battery.
If the signal gets loaded down you could add a 10K pull up resistor, but I doubt you will need it.
If the signal gets loaded down you could add a 10K pull up resistor, but I doubt you will need it.
Map63Vette
Well-Known Member
I'm splitting the tach signal to run my Megasquirt and my column mounted tach and haven't had any issue so far. I had originally tried to use the ignition output of my Megasquirt to run it, but it was easier to just use the signal straight from the MSD box.
Thanks! I think I will try it.
Peter Bates
1973 Cuda owner for 36yrs
If you have a obd port for the computer on your hemi you could buy a Dakota digital interface unit. It has two signals for the tach. That's how I was able to get a clean signal from my CPU to my speed hut tach. Now I just need to get a signal to my tcu tranny controller. I tried to no avail to pull a signal off the motor
Update?
Buschi340
Well-Known Member
so you can use that one Output cable to run for example 2 tachs?
Map63Vette
Well-Known Member
As far as I'm aware you can. It's just a square wave signal and it's not meant to carry power, just voltage level. Pretty sure tachs would be high impedance devices that have large input resistance so they don't have a big power draw. I'm sure the output line is limited in what it can supply though, so if you stacked enough things together I could see it potentially being a problem. I don't think you'd have issue running two things though.
Buschi340
Well-Known Member
will figure that out this winter. just two tachs, not an endless amount of tachs.. 
The one in the dash is hard to read sometimes
The one in the dash is hard to read sometimes
famous bob
mopar misfit
I DON`T REMEBER OFFHAND , BUT I DIDN`T HOOK BOTH UP TO THE BOX, THINK FAST SAID NOT TO. Call fast and ask for Dave.will figure that out this winter. just two tachs, not an endless amount of tachs..
-
