I'm about to install my rpm switch and i am wondering which wire is the switched 12v line to the trailing plugs or the leading plugs. What colour is it?

My rpm swithc has 4/6/8 and "coil per plug" modes. If i hook up my switch to the tach output on the leading plugs (or trailing plugs), which configuration will it need to be on for each setup? The female bullet type connectors are tach outputs...but what setting on my rpm switch will interpret the signal properly?

Thanks

 

if you look at the trailing coil, the tach out put is a yellow wire with a dark(blue?) tracer. this wire goe directly to the tach. the power wires are black with yellow tracers. you need to make sure you don't interupt the voltage to the coil, they dont work well with low voltage.

mike

 

That short wire with a bullet terminal is paralleled off this wire, so a diagnostic tach can be used. Just plug the rpm switch into that. The main relay sits close to the trailing coil so you can get switched 12V from there.
The trailing plugs fire as often as 4-cyl plugs, so hook it up to the trailing coil and set the switch to 4.

 

Hmmm...if I can't interrupt the voltage to the coil, what power source can I hook them up to? An rpm switch in parallel with the coil should not lower the voltage going the coils anyways....

(This is where NZ teaches me more about physics )

Nima

PS. What does this main relay look like?

 

the main relay is a gold boxy looking thing crammed into the left rear of the engine compartment, near the trailing coils. you could also run power from the fusebox behind the battery

mike

 

[.
The trailing plugs fire as often as 4-cyl plugs, so hook it up to the trailing coil and set the switch to 4. [/B][/QUOTE]

So with the above said, It Is suggestable to hook up a dyno at the Trailing Pack and configurate It at 4 cylinders? Anything else I should tell dyno man when he Is typing Input on my 88 GXL?

 

You can also pick that same yel/blu tach wire at the power steering computer (driver side under dash) or the back of the cluster.

I always use it at the power steering computer for remote starts and turbo timers. 6 cyl setting for remote starts.

 

Don’t take power from the coil, just the rpm signal. I’m assuming the rpm switch needs power, ground and signal, right? Take switched 12V from the main relay (use the black wire with the white stripe on the 2-pin plug), signal from the coil (short yellow wire with the blue stripe, with a female bullet connector on the end) and ground it wherever you like. It doesn’t, just use the little connector Mazda kindly provided for this very application.

 

Not switched.

 

Yep.

 

Thanks NZConverible. But why, for example not the Leading? Anything else dyno man should know when setting up my FC? I ask b'c he's never did an RX-7.

 

Because the leading plugs use the "wasted spark" method, meaning they fire twice as often as the trailing. Read this thread for more info. It's just a car, they all work the same on the dyno!

 

Okay I get It. Have It hooked up on the Trailing Pack and have It set for 4 cylinder.

I'm not opposing your suggestion, but wouldn't the wasted spark on the Leading Pack misinterpret the correct signal when ran on a dyno? I had dynoed my FC on the Leading Pack which pumped out more Torque than HP. I mean, shouldn't It be the other way around?

My dyno report sheet came out with a max power of 114.4 and a max torque of 121.0. I think perhaps the dynoing on the Leading Pack through the actual dyno out of whack.

I'm not starting a thread "why Is my n/a" slow but am trying to Interpret the significance of Trailing over Leading (or other way around) let alone the many mods I have yet dynoed below factory standard at the RWHP. I mean, with my many mods I should be pumping more HP. Also, even for that matter, how do you have more HP than Torque?

 

Did you read the thread I linked to? The leading coil simply fire twice as often as the trailing coils (yes, there are two in the pack), that's all. If you hooked a tach to the leading coil and set it to 8-cyl, it would read correctly.

 

I guess I'm led to conclude dyno man set It up Incorrectly than. I did catch your point the first time though. Seeing how I had VERY low HP and higher Torque than HP.

Very soon will dyno again. (This time 3 times):

-At the Leading Pack set at 8- Cylinder
-At the Trailing Pack set at 4- Cylinders
-At the Trailing Pack set at 4- Cylinders, with a Walbro Fuel Pump, non regulated. (until I get my S-AFC).

Thanks

 

what setting for a tach ?

 

My leading and trailing packs are connected by that wire (with female but connecter , rpm signal). Dose one or the other need to get the signal from that wire? What I'm saying is, lets say the trailing pack sends the sig. to the leading pack or vis-a-vers-a. Is that how it gets the sig. or dose it get it from the harneses ?

 

anyone?????

 

http://www.teamfc3s.org/info/articles/demystifying.html

 

As mentioned in the post that you quoted, 6 cyl, works the best on the Remote starts and T-Timers I have installed.

I suppose it has to do with the 3 fires per revolution of the crank

 

No the ECU sends the "fire" signal to both leading and the dual trailing pack.

The wire I mentioned above is a summed tach signal, from the trailing coil packs