25 replies to this topic

[Bart]

Hey guys
Got a little issue with my tacho so since you guys have helped me out in the past I thought i would throw this one out there also.
So I have a Nissan V8 and it has 8 coils. Im trying to find out how i would connect my tacho signal wire to these coils.
Has anyone done a similar connection?
Alternatively I can get a signal from my programamble computer but it dosnt seem to be working off this, incorect signal for the LJ GTR tacho?
PLEASE EXPLAIN

Edited by Bart, 28 February 2009 - 11:04 PM.

[Bart]

I was told some tacho's are triggered differently. I guess i need to know how the LJ GTR tacho is triggered

[rodomo]

Your GTR tacho works off 3 pulses per rev (being 4 stroke) from 1 coil in it's natural state.

Maybe if you tapped into 6 of your 8 negs from your coils, you might get it close?
Run the 6 wires into 1 that then goes to your tacho.

Let�s say your firing order is 12345678.
I would tap into 123 & 567 (pick-up 3, miss 1, pick-up 3, miss 1)
Your tacho needle might be too slow to respond to the "miss" at idle and would be more accurate as the revs rise?

Alternatively, run all 8 neg wires into 1 and put a potentiometer in the 1 wire.

Ol' Fred:
http://www.gmh-toran...ith electronics

[Rockoz]

Wouldnt do that.
You would need to put diodes in to isolate the coils from each other. Otherwise you gunna have some great misfiring.
Would think that possibly the easiest way would be to get the tacho from the donor vehicle and modify for fitment in the torana dash.

[rodomo]

Why would it missfire?

"Would think that possibly the easiest way would be to get the tacho from the donor vehicle and modify for fitment in the torana dash."

In other words, run the guts and re-calibrate the face?

[Bart]

Hmmm
I realy wanted to run the GTR tacho if possible.
Its got me curious as to why it dosnt work with my programable engine managment computer as it has the tacho out put wire. I spoke to the manufacturer of the computer and he said to find out what type of tacho it is? Cant remember what he specified what to find out, he was saying how it triggered, magnetically or somwthing of that nature??

[rodomo]

You would need to put diodes in to isolate the coils from each other.

Correct, reading things a bit clearer this morning.

[Rockoz]

Hmmm
I realy wanted to run the GTR tacho if possible.
Its got me curious as to why it dosnt work with my programable engine managment computer as it has the tacho out put wire. I spoke to the manufacturer of the computer and he said to find out what type of tacho it is? Cant remember what he specified what to find out, he was saying how it triggered, magnetically or somwthing of that nature??

You may be able to program the computer to send out the right info to work your tacho.
What type of computer is it?

[Bart]

You may be able to program the computer to send out the right info to work your tacho.
What type of computer is it?

Its an EMS 8860 Sequential Motor sport
One of there top of the range

[Rockoz]

Have you got the tacho plugged into output 3 and a resistor fitted?

[Bart]

Have you got the tacho plugged into output 3 and a resistor fitted?

Yep
500ohm

Edited by Bart, 01 March 2009 - 01:52 PM.

[Bart]

Have you got the tacho plugged into output 3 and a resistor fitted?

Do you mean output 3 as 12V?
There are 3 connectors on the tacho
12V signal and Grnd
Instructions said use a 500ohm for the 12v and connect the EMS tacho out put to that?

[Rockoz]

Thinking 12V to 12V on tacho
500 ohm from 12V to signal
Output to signal
Ground to ground

[Bart]

Have you got the tacho plugged into output 3 and a resistor fitted?

I just re read your question, im using output 4 from the EMS which i enabled, not 3 as its being used
It says i can use o/p 1 to 4

[Bart]

Thinking 12V to 12V on tacho
500 ohm from 12V to signal
Output to signal
Ground to ground

12v as is
Plus another 12v, with 500ohm to signal on tacho
EMS output to 12v, with 500ohm to signal on tacho

I should have mentioned all Auxillary outputs of EMS are normaly grnd

Edited by Bart, 01 March 2009 - 02:16 PM.

[Rockoz]

Try my way.
EMS output should not go straight to 12V
Read the details on site.
Heres how I think it should work.

EMS output goes to ground. But needs 12V reference so it can sink some current to get a value.
Thats why the output goes to 12V through a resistor. It creates a circuit.
If you now take the signal from the ems side of the resistor, the tacho will read the fluctuations as it would points opening and closing.
I think putting ems output direct to 12v would be not good for long time happiness. Good chance you will let the smoke out of something important.

[Bart]

Try my way.
EMS output should not go straight to 12V
Read the details on site.
Heres how I think it should work.

EMS output goes to ground. But needs 12V reference so it can sink some current to get a value.
Thats why the output goes to 12V through a resistor. It creates a circuit.
If you now take the signal from the ems side of the resistor, the tacho will read the fluctuations as it would points opening and closing.
I think putting ems output direct to 12v would be not good for long time happiness. Good chance you will let the smoke out of something important.

Quote If you now take the signal from the ems side of the resistor, the tacho will read the fluctuations as it would points opening and closing.
Ok, take the signal to where on the tacho? the 12v, signal, or grd? Im guessing the signal of the tacho? Which is basically what i have done

[Rockoz]

Diagram 1 is as it should be
Diagram 2 is trying to work out what you said. No offence intended but sometimes translations can be difficult.

[Bart]

Diagram 1 is as it should be
Diagram 2 is trying to work out what you said. No offence intended but sometimes translations can be difficult.

LOL sorry mate the first diagram is exacly what i did

[Rockoz]

Has the ecu been programmed to provide the correct output?
Output has to be switched to Tacho in the setup menu
If it has you may need to change tacho
Have you checked tacho on another vehicle?

If thats the motor in your avatar where did you get the throttle bodies?

Edited by Rockoz, 01 March 2009 - 09:14 PM.

[Bart]

Has the ecu been programmed to provide the correct output?
Output has to be switched to Tacho in the setup menu
If it has you may need to change tacho
Have you checked tacho on another vehicle?

If thats the motor in your avatar where did you get the throttle bodies?

LOL you digress, nice throttle bodies ay? Unfortunately not mine but i have the same/similar motor in my LJ, in the avtar its a VH45 mine is a VH41 with twin turbos.
Yes i have enabled the ecu for tacho on Auxilary output 4 which is yellow orange wire
You may be right i may need another tacho, i may steal the one out of my dads boat to see if its my tacho, more work i didnt want to do

[Rockoz]

You may be able to get another tacho that will fit in the dash. Just look for one with similar scale, and change the needle and slot it in.

Trying to find some different throttle body options.

[Bart]

You may be able to get another tacho that will fit in the dash. Just look for one with similar scale, and change the needle and slot it in.

Trying to find some different throttle body options.

Throttle bodies for what?
You may have to fab some up?
Maybe use a bunch of motor bike thottles?

[Rockoz]

Got some BMW bodies coming but they are only around 35mm apparently, but that gives equivalent of somewhere near 100mm single throttle body.
May be adequate for 5 litres. Will give me something to look at anyway. Might have to fast track the lathe i was looking at.