RPM signal connection

Hey
I'm in the process of upgrading my methanol injection setup by using a new controller requiring a rpm feedback.

I searched and found a Mazda technical bulletin for remote starter connection with a white wire out of the ecu harness made exactly for that...http://am.mazdaserviceinfo.com/libr.../en_us/pdf/Remote_Start_Addendum_(Mazda3).pdf
I checked it with a meter and see an average voltage and frequency fluctuation corresponding to rpm so i was confident it would work....tried it, worked for a short time and after few rev, engine fall on 3cyl and ending up burning cyl #1 coil and blow ignition 20a fuse...youpi!
After replacing everything, i checked that white wire is directly the firs wire of the #1 coil. I will have to double check with a scope the exact signal and why it wasn't compatible.

So is any of you used to connect a rpm feedback to a device ? If so please let me know which signal you have used...
My last call is to add an extra crank sensor and keep it completly separated but i expect some of you already figured this out and i'm looking for advide.

 

Out of curiosity, which controller are you using?

tapatalkin

 

i found an advanced one that allow a lot of different configurations, few outputs and inputs etc..... https://torqbyte.com/products/torqbyte-cm5-lt

wiring diagram
https://cdn.shopify.com/s/files/1/0810/3325/files/CM5-LT_Quick_Connect_Diagram.pdf

i was planning to connect the trigger like if i would be using a split second additionnal injector controler but it doesn't work as i described above...

 

ok I checked yesterday the signal with a scope and it really looks fine, i just don't get why i burned a coil when trying it...

 

You want the power wire for the coils before it splits apart to each coil. Should be a black/white wire with grey spots on the coil harness, check by the large connector. Not sure if it's different for gen2.

 

It is a 2007 gen1 but the common signal you talk about, i would think will remain at constant 12v regardless of trigger signal ? Maybe i could use it with a device converting current pulse signal into a voltage pulse? The controler need a kind of square wave voltage input if i read it well...

By the way, im i wrong or you should change you signage for White speed6 to replace the grey one ?

 

That's the tach wire used for wot boxs and other stuff so I don't see any reason why it wouldn't work for your application.

Haha, thanks I forgot, I don't see signatures on my phone.

 

i will investigate on it. But i was on the impression that we have a common ground, a common + and 4 individual 5v trigger signals so the other 2 should be constant voltage. But maybe with wire loss, the power wire show some voltage drop synchronised with coil pulses...it worth to try!

 

i finally got it to work.

i made a signal converter from the 5v tach to 12v using a transistor and some resistors. I put it in a smal plastic box and is seen to work well.
http://www.electro-tech-online.com/attachments/tach-buffer-png.16286/

tomorrow i will install the advanced meth controller

 

Did you ever find out how the coil blew out? Maby the cm5 controller kept the coil on for to long of a duration?

I have used that white wire for many remote start installs. Most of thoes starters have the tac input isolated.

 

I really don't know. The input circuit of the cm5 should work directly and it works on Audi and BMW tach signal just fine.
I could have got something bad with the coil at the exact same time....I played with the coil connector a lot before using the white wire.... Not sure if bending one of the tab may affect the igniter inside....
Cm5 supplier returned me the input circuit and there was resistors 10k or 100k to limit any current draw but there was some tiny filtering capacitors after the resistor. Usually that small capacitance should not hold the igniter signal back into the coil thru the resistor but it is the thing that have the greater chances to affect the coil....And this is why i made an isolator between the 2.
To be sure of it, i would have to put a scope and check for the signal change when i connect the CM5 directly on it but i don't want to burn another coil so i won't do it