individual coil signal to tach :( Options

[match220]

my setup
gen III 3sgte with autronic ecu + individual audi 1.8t coils (the stable year versions). Each coil has its own built in igniter and 4 pins: positive from switched connection, signal ground, ecu signal, and power ground. And the coils are TCI coils, not CDI, not that it matters. I'm getting tired of not having a tach signal so I'm hoping you guys can help me figure something out aside from running 4 diodes in-line with the signal ground and jumping off one of the coils to run to the tach.

1mz tach
I was hoping I could read up on how it was done on the 1mz swap which has a 3 coil wasted spark setup, nada..the 1mz swap just requires the gauge clusters to be disassembled and mixed together to work.

mixing audi and toyota gauges
My initial plan was to mix the audi gauges with the celica gauges and use the tachometer output from my autronic as the tacho signal, not going to work unless I recreate the circuit-board for the audi and wire it into my celica. I bought the gauges off of the same kind of car the coils came off of, but they are all driven by a signal from the ecu it looks like, not to mention it's just one big circuitboard.

running only audi gauges
I've also thought about running the audi gauges instead of my celica gauges, BUT I would have to wire me speed sensor and fuel level sensor into the autronic and run outputs to the gauges.

using a tach adapter
Now I'm wanting to run the tach signal off of the autronic to the celica gauges. Is there an adapter I can buy? I can configure the autronic to run a normal tach output or invert the output to the tach as either a .5 msec pulse or 1 msec pulse, nothing else.

[Smaay]

Dakotadigital.com has a tach adapter.

[pitcelica]

Build your own like this one : http://www.msextra.com/doc/ms2extra/MS2-Ex...re.htm#tachoout (go to the "High voltage" diagram)

You will only need a 2N5551 transistor, an automotive relay coil and a 1K resistor. Use your Autronic tacho output. Just make sure that you remove the small "contact lever" inside the relay unless you want that annoying relay clicking sound each time your Autronic send a tach pulse.

Sam

[match220]

Build your own like this one : http://www.msextra.com/doc/ms2extra/MS2-Ex...re.htm#tachoout (go to the "High voltage" diagram)

You will only need a 2N5551 transistor, an automotive relay coil and a 1K resistor. Use your Autronic tacho output. Just make sure that you remove the small "contact lever" inside the relay unless you want that annoying relay clicking sound each time your Autronic send a tach pulse.

Sam

nice!!! I have enough relays lying around that I can sacrifice one of them. I just bought packages of 15 2n551 transistors and 50 1k ohm resistors, so I'll have plenty of spares..haha. If anyone reading this wants some resistors and transistors PLEASE let me know.

[Syaoran]

I'll definitely let you know when I get things underway. I need that for my MS2, I'm going to be using the wasted spark setup that came with my new engine.

[match220]

I'll definitely let you know when I get things underway. I need that for my MS2, I'm going to be using the wasted spark setup that came with my new engine.

Megasquirt is the MS2 I assume? What engine with the wasted spark setup?

[Syaoran]

5SFE running on Megasquirt-II yes.

[match220]

SOOOOO..here is my adapter. I made it just like the diagram on msextra. The relay I used had the gate in a place to where I had a pocket to put the transistor and resistor in when I wired it in, so I managed to fit everything in. I made a youtube video on the whole process too that will be uploaded in a few hours it looks like (1 hour long, I'm adding links later to jump throughout the video), I'm not editing it so it will stay HD, it will just be long. I tested everything yesterday before I soldered the adapter, everything was twisted together or held by either me or my roommate, and it worked intermittently (most likely a bad connection somewhere since everything was held or twisted together). I had my sm4 set to a 1 msec pulse. It looks like I can use the same adapter. I'm going on a run with some friends, but I'll install it tomorrow and make sure it works.

video: when it finishes uploading
http://www.youtube.com/watch?v=5ZHEYSGKmkc...eature=youtu.be




This post has been edited by match220: May 16, 2013 - 10:29 PM

[Syaoran]

That looks great

[match220]

That looks great

it didn't work when I wired it in, but it did work the other day when everything was twisted together before soldering. I've double checked the wiring and it is all solid. The one thing I didn't think about was the electromagnet being right in front of the transistor possibly killing the transistor. I know transistor chips in a computer will be killed easily with a magnet, I didn't even think about the coil effecting it. I'll double check settings in my SM4, but I'm pretty sure they are right and the transistor is dead from being in front of a magnet.

[Sunny]

Hi,

thanks a lot for the link, i did the high voltage diode mod to my wiring tree included in a connector so that the toyota cops are able go spent the rev meter a signal, hope it works currently i'am not sure
becouse they write that only two coils are needed, can this anyone confirm?


greetz

[match220]

Hi,

thanks a lot for the link, i did the high voltage diode mod to my wiring tree included in a connector so that the toyota cops are able go spent the rev meter a signal, hope it works currently i'am not sure
becouse they write that only two coils are needed, can this anyone confirm?


greetz

I'm pretty sure my tach doesn't work anymore. When I was building my engine the convertible top's back window fell through..and it let a ton of moisture in, which mildewed. I had to scrub everything in my car and suck it up with my shopvac. As a result my water temp gauge is all out of whack and shows very hot when cold. The rpm gauge jumped a bit with the first adapter that I made by twisting together, the after soldering a second one, resoldering a third one, and now after making a different adapter. Nothing seems to work and my settings are correct in the SM4. If anyone has a tach..I could use one.

[match220]

yeah, it's a bad tach. I connected an LED to the tach output of the Autronic ecu, watched the light pulse. So now I need a tach apparently.

[Hafkai]

There is a quite easy way to get our stock tach working with most aftermarket ECU signals. You just have to take out your tach and take a look at the circuit board, there is a ~43kohm resistor between the signal input and the IC that controls the tach. I never measured the voltage spike that is coming from the stock ignition so i dont exactly know what the voltage the IC receives should be but i tried some resistors and the tach was ok with a 1kohm resistor instead of the 43kohm.

While i was playing i checked what kind of signals the tach could handle, well the IC seems to be happy with everything, PWM from 1-99%, sinus, saw, triangle and of course square, so every aftermarket ECU should work.

Since my ECU pulls the tach signal to ground i had to put a pull up resistor (~500ohm) between 12V+ and the tach signal cable. Seems to work flawless on my tach.

I can upload a pic of the resistors later.

[match220]

There is a quite easy way to get our stock tach working with most aftermarket ECU signals. You just have to take out your tach and take a look at the circuit board, there is a ~43kohm resistor between the signal input and the IC that controls the tach. I never measured the voltage spike that is coming from the stock ignition so i dont exactly know what the voltage the IC receives should be but i tried some resistors and the tach was ok with a 1kohm resistor instead of the 43kohm.

While i was playing i checked what kind of signals the tach could handle, well the IC seems to be happy with everything, PWM from 1-99%, sinus, saw, triangle and of course square, so every aftermarket ECU should work.

Since my ECU pulls the tach signal to ground i had to put a pull up resistor (~500ohm) between 12V+ and the tach signal cable. Seems to work flawless on my tach.

I can upload a pic of the resistors later.

I've only had the tach barely jumping since I have finished the engine. Today if I have time I will take out the gauges and look for the problem if I can find it.

[Hafkai]

I left the 43k ohm resistor in place (the one under the 1.0k) because it wont have any effect and i was to lazy to remove it ....
The 0,56k Pullup is only needed when the ECU doesn't output a positive voltage as RPM signal and pulls to ground instead.

[Smaay]

oooohhh, interesting, will this work with the stock ECU?

This post has been edited by Smaay: Sep 9, 2013 - 8:15 PM

[Hafkai]

oooohhh, interesting, will this work with the stock ECU?

I completely forgot to reply ... it should work with the IGT signal if you dont use the stock ignition system, if the ECU has more than one ignition output you have to build something with diodes so that the tach gets every ignition signal.

[Sunny]

Hi,

on my engine with haltech i use the tach-output channel with 5V and replaced the 43KOhm resistor against a 1kOhm on the rpm gauge electronik (as shown above)
the haltech itself has the pull-up internal

greedz

[davenirish]

Sorry to bring a thread back from the dead, but I am doing a st215 swap and would like to get the tach working, I would like to try the resistor mod has do you think this would work for the out put from the stock st215 ecu

I am also having a issue with the temp sensor spiking at a low temp. IS there a mod for it? or am I going to have to drill and tap my old sensor in the water neck somewhere?