You have 2 ignition firings per cycle (per cylinder). So it sounds like your reading all of them. So there should be a switch on your tach for 4,6,8 cylinders. So I you want to select 8 cylinders.

 

i do have it set to 8.

 

Then get a new tach. The issue is the interface between your tach driver and the tach. The tach driver should read one pulse per revolution of the flywheel and the tach should average the results. If the tach is being overdriven, then its reading garbage data (noise essentially). You might get away with putting a 220ohm resistor between the tach and the driver. But without seeing the tach input on a scope, and not knowing anything about the tach circuit it's all a crap shoot really.

 

Maybe its in metric.......

 

Naw man! It's hex. Supposed to be binary. arty:

 

this is my second tach that i have gotten because of this issue. i don't know if it is the tach's fault or the drivers fault or what. i'm just tired of buying new tachs only to find i have the same issue.

 

Then I would start to look at your tach driver. It's sending to many signals, or the signal is corrupted. But! too many products are made for the venerable 'cheby V8'. You have a completely modern ignition system. I suspect your having 'old tech meets new tech' issues. Guessing here.

 

the way i have it wired is the tach driver connected to the CPS sensor wires in 2 places , and then power connected to the ignition only source grounded behind the a pillar. i don't see what could be going wrong. maybe i should replace the t-taps on the CPS wire?

 

No. I think you did it correctly, and I will assume you did not do a sloppy job. One thought though. How did you adjust the CPS? I don't know myself. but assuming it's a common magnet driven hall sensor. Did you adjust it to spec? If the flywheel teeth are semi-magnetized they could be driving the sensor a bit. The only other thing I can think of other than the tach itself is the ground. Not where you put it, but that you have a noisy ground. But that's sorta 'out there' ya-know! You realize I am just guessing here right? Without seeing what is going on (as in putting a scope on it) it's the best I can do.
Edit: Wait, What? What do you mean by 'taps'. You are using a standalone CPS right? You did not tap into the ECU CPS correct?

 

oh theres a wire that runs behind the glove box that i tapped into per another thread on here (ill get the link in a second); not the one in the engine bay.

 

What wire is this behind the glove box? The ground? or ?? you are aware that there a ground 'zones' in a car yes?

 

http://forums.focaljet.com/duratec-tuning/507187-how-duratec-aftermarket-tachometer-installation.html

that thread was how i did it.

 

check the link i posted. it will probably describe the wire better than i can. lol.

 

Tryng again. What is the purpose for the wire you used to tap into the wire behind the glove box. Power? Ground?

 

that wire is where it gets the rpms from.

 

See my post in said link.

I'd venture a guess that you're wiring is all screwed up. The Ford Tach Driver only has 3 wires that don't go to the tach; power, ground and signal from the CPS.
You can tap into the CPS either at the sensor or at the ECU, but not both.

 

I'd venture a guess that you're wiring is all screwed up.

I would venture a guess your right!

 

the red goes to power, the black tie ground, the green to tach. The other side had two wires. One white one black. I booked both of those up to the specified wires in the guide from the link. Where did I go wrong?

 

In a wasted spark type ignition system (which is virtually any vehicle made after about 1996 with an electronic ignition) the ignition coils fire once every 360 crank degrees (remember there are 720* in one complete combustion cycle).
This means for a tachometer that is based off voltage (frequency, Hertz) the tachometer signal will have to be cut in half to give an accurate reading of actual RPM. If not it will read double the actual RPM's. (Also why digital timing lights will not work on correctly on most newer cars)

A tachometer based on amperage will simply calculate the RPM from the input current. This type is almost always hooked directly to a Hall Effect Sensor (Crank Position Sensor, Vehicle Speed Sensor for speedometers). This is also how some factory tachometers work.

Most all (that I'm aware of) aftermarket tachometers work off voltage and not amperage.
I'll bet that if you hook your tach up to any power wire of an ignition coil and set it to 8 cylinder your tach will work just fine. If not try 4 cylinder. I really don't see why all the hubub about tach adapters, I doubt they are actually needed for most applications.

OK. So if the FR tach adapter is supposed to hook to the CPS. That means it's taking amperage and converting it to voltage to drive an aftermarket tach. I'm not good with electronics but I'm venturing a guess that inside the tach driver is a resistor or two and a diode.
The reason the FR tach adapter works for both the Mustang and the Focus is that the CPS's of both produce the same amperage, both have a 36-1 trigger wheel in the flywheel.

The cylinder switch on a tach is simply a resistor. Not sure but guessing that is the tach where designed for a 4 cylinder the resistance value would be different than that of one designed for a 8 cylinder, when flipping the switch. So maybe if you set yours to 4 cylinder it'll work just fine. Dunno.

Still say you can take the adapter out of the equation though.

 

It is connected to the ignition power now, but ill try 4 cyl and report back