Tacho Booster !

[TA-022]

there ya go then .. trimpot tunning FTW! god love Toyota fore thought!

[EldarO]

1UZ ecu has no tacho output.
Tacho signal comes straight from the ignitor and is the same signal as 2JZGE.


A lot of Toyota dashes already have the trimpot built into the dash.

excellent, + rep CrUZ.

Elmo.

[lexsmaz]

On the 1uz motors there is only 1 tacho output out of the 2 ignitors .. so the tacho needs to be wired / resistance adjusted to read as a 4 cyl ... When i wired up my 1uz into my 929 mazda, was originally a 4 cylinder hooked the output straight up to original tacho & works perfectly ...

[TA-022]

in that cas Eldaro if you have a trim pot in the tacho in question drop the resistance by approc 11% .... i went up 11% so if your going 6cyl to 4 i assume drop 11.?

[rxbenny]

Do i need this booster or should i put in a capacitor.

Here is whats going on

Background

From what I can gather the coilpacks are from a VN commodore and i am using a bosch ignitor with a motec M4 and i have used all my outputs.

The Dash tacho is a JDM digital dash tacho.

Problem

My tacho works showing half rpm from either coil when one IN4004 diode is used but when i hook up both the tach doesnt show any rpm.

I have used the circuit described by Henn with the zener reverse biased and with or without the resistor to earth it makes no difference i have no tacho displayed on my dash.

The tacho worked when fed a signal from the ignitor when i had a 4age inthe car.

any ideas?

[ViPeR_NiPPleX]

So you have tried using two diodes (one from either coil) and joined them to the tacho?

[rxbenny]

yes i have tried just 2 diodes,

i remade the circuit as described by hen and i will be trying that today.

using
IN4004 x 2
IN4744 x 1
1k 1 Watt Resistor

[cambelt]

Hello
Well a while ago i made the ribfeast tacho booster , I tried it on my 7MGT and it didnt work , but when i tried it on a supra last week it worked fine ,ruling out that i made the circuit correctly. The 7M igniter must have a slightly different output to th JZ igniter . Does anyone know how to make it work on the 7M.
Dave

[ViPeR_NiPPleX]

Dave,

I made one that worked flawlessly with Yian's 7mgte/ma61. Check which transistor you are using, I prefer the BC546 as I have plenty of them 2k2/2k7/3k3 resistors have worked for me too. 1n4007 or basically any diode should work.

James

[cambelt]

I made it to the specs using the BD transister . i,ll try the bc 546 next time .
thank you
Dave

[fester]

OK guys Crudzila directly me kindly to this thread when I posted a similar but opposite question in an old tacho tthread that Hen started.

I need to do the opposite to what you guys are doing in another project of mine.

I need to convert a voltage spike signal from old style coils to a square wave signal for a late model tacho that would normally be ECU triggered.

I'm trying to look at putting a late model tacho into an older Ducati that was and still is carbed. The original tacho is mechanical so there is no tacho wiring at all.

Also how can I test what signal the late mdoel tacho requires as I can't find anyone who can tell me. I am assuming it will probably be a 5 volt square wave but how do I test in case it is different.

Can you show me the wiring diagram to do this as I too am pretty average with electronics bits and pieces.

Gavin

[ViPeR_NiPPleX]

It's going to be either 5v or 12v (typically) depending on what the original igntior/ecu outputted. If you have the equipment (audio generator + oscilliscope) then you can determine accurately what it will expect....

What you are trying to do is condition the signal. There are a few circuits which can achieve this. My favourite which is floating around on megasquirt forums is the optocoupler one, as it isolates the high voltage peak from the low voltage output (and it does it cleanly).

I'll try to come up with something if no one else does when i'm not about to sleep

[Ribfeast]

Maybe even a zener diode to clip the sharp peaks off it?

[fester]

You could also make that

Cheers
Wilbo

Hey guys I'v read these tacho threads and they are making more sense everytime I read them. The wiring diagram i still a little confusing but I think I get it now.

MY BIG QUESTION THOUGH (not shouting sorry) is anyone help out with this working ona diesel. I pick up tomorrow a 1990 80 Series Landcruiser that originally came with a factory turbo 1HD mechanical diesel so I guess tacho triggered from injector pump. The last owner did a conversion to a 1HD-FTE which is similar motor but multivalve head and importantly ECU controlled injector pump. He never got it working saying the later ute it came out of had 3 tacho wires and the older tacho in the car has only 2 wires. Now I'm hoping/guessing Toyota used the same triggering signal from the ECU as most of their cars so I hoping the booster diagram previosuly posted will work.

Can anyone help me with this. I tried PMing sideshow to even look at seeign if he could make one up but he does not accept emails or PM's.