I would like to know where did u guys tap a clean signal for the tachometer or rpm signal? cause i need to know a source for my M500 datalogging wideband.

thanks a lot

 

Off of the trailing coil pack, there should be a yellow/blue (S4 cars) single connector that can be used...

 

actually i tap it there , but there seems to be a lot of noise from that signal..... it wont read right...

 

iwas told of a good wire off of the ecu
let me try to grab the photo for you

 

ok look under the thread shift light install right below this

 

err thanks but im not running the stock ecu anymore....im running a microtech and i sold the stock harness and ecu.

any idea?

 

oh ok then nevermind

 

Your best bet for a tach signal is at either the power steering computer, or gauges if you are running a non OEM ECU or hooking up remote start. That way you don't have to worry about any echo off of the coil.

Again that same Yel/blu wire.

 

well how come that yel/blu wire now is having so much noise till my datalogger seems to go up and down....

 

Probably where you are running your wire is too close to the coil or a bad cable

 

too close to the coil? how am i suppose to insulate it or something?

 

wire it inside (as I mentioned in posts above) and see if it solves it.

If it does not, you can always use a tach filter.

 

thanks whats a tach filter and where can i purchase one?

 

you build it yourself, and it would not solve the issue if you have noise from the coil or cables and were still hooked up under the hood for your tach connection.

 

hmm now im guessing it might be the CAS wire that it is near with as both are in the same engine wiring loom. will try to pull it out and wire it into the cabin..... thanks...

 

Ah, yes none of the CAS wires will work for a tach signal

 

what i meant was they are quite close together, i didnt tap the tach signal from the cas.

shall post updates if get it done.

thanks icemark for the fast reply

 

Sorry, But While We Are On The Subject, Has Anyone Heard Of The Tach Grounding Out? Had To Keep Replacing My Ignitor On The Side Of The Distributor Until I Unhooked My Tach From The Coil. Now I Have No Tach.

 

i havent heard anything like that , eventho i tried insulating the wire and wire it into the cabin ... still didnt solve anything. i tap it from the yellow/blue wire..... damn now im thinking if i should sell the m500 since i cant datalog my friggin rpm

 

okay try the tach filter on the wire (for both FC mania and twilsn7).

To build the filter, you will need a 1 amp diode (1N4004 is just fine) and a 4.7k 1/4 watt or 1/2 watt resistor.

On your tach connection, put the diode inline with the Bar of the diode (cathode) facing the device (aftermarket datalogger, aftermarket tach, etc) and the non bar side of the diode facing the factory wire where you got your tach signal.

Now you are going to "T" in the resistor (either side of the resistor, it does not matter) between the bar side of the diode and the aftermarket device. The other side of the resistor is going to tap onto a good 12 volt ignition switched source (so that the resistor becomes the center part of an "H" between an switched ignition souce and your tach wire after the diode.