I need a Tach signal for my Data Logger. The signal has to be a 0-14v, 50% duty cycle, square wave. pretty standard fayre on later COP systems - I thought.
I ran the logger on my DD over the Winter to test and ended up taking the tach directly from one of the COP feeds without problem.

SoI tried the same on the Mustang but the RPM is literally all over the place, Over reading, under reading, just horrendous. So I got one of those inductive sensors and hooked it around the coil pack feed butI get absolutely Nothing inthe form of a useable tach signal, Nada..
The next day, after some thought, I piggy backed onto one of the injector feed lines and got a "useable" tach. I say useable, but the problem with the injector lines is that they don't always give me a constant RPM number, mostly when cruising (See video below).I guess it's the fuel system varying the pulse width [?].

So, does anyone know whereI can pick up a reliable Tach signal without having to spend anymore money LOL And, of a lesser importance, why are the coildriver lines so electrically'dirty'?

http://www.mkeeler.com/upload/mustang/Tach_issue_1.wmv

 

my first thought, is that you need
a tach driver, to feed the tach logger.....

i see that you don't want to spend anymore money
though.....

what's the model # of your logger...

 

Yea,I have one. That's the inductive sensor.

The unit is the MSD G2X http://www.msdignition.com/new_products/g2x.html And the sensor/Tach driveris their ownMSD unit specifically recommend (if needed).

 

Interesting. I'm an electronics guy, but not in the automotive field, and not 100% familiar with the signal going to the COPs. Is the wire you used shielded? If not, perhaps it was picking up other nearby noise and sending a dirty signal to your data logger.

 

No. The cabling from the optionalsensor isn't shielded and neither is their direct cable so I'm guessing it isn't a problem. Certainly at these voltages & FrequencyI can't see interference being a player although right now I'm almost ready to believe anything [&:]

 

ok....if it's an inductive sensor, we
need a clean source for an expanding
and collapsing magnetic field.....

this would be present at all of the
8 C.O.P connectors....perhaps one of the
others, may be a bit cleaner

 

Wow, it's a ghost town here when the questions get beyond radios and noisy gears eh? [8D]

I've ordered an Autometer tach adaptor even though MSD say I don't need one. Now I have to locate the COPs common 12v feed so i can splice into it

http://www.autometer.com/download_instruction/561.pdf

I shudder to ask, anybody know where that is? or got the COP wiring diagrams in PDF ?

 

Marcus the only thing i can provide is the link to the workshop manuals and such

http://iihs.net/fsm/?dir=1

I was able just to clip on the coil on for my shift light......my setup isnt fancy like yours

Good luck!

 

Thanks Matt. If the cable colour codes there I should be good to go !!