<ANSWER JZGTE igniter = dumb> JZ-GTE igniter / IGt

[wilbo666]

Hi,

I'm wondering about the suitability of using a JZ-GTE (1jz and 2jz igniters are the same) on an aftermarket ECU...(if the dwell time in the igniter is constant then I can't see why you couldn't use it with an aftermarket ECU).

I'm trying to ascertain exactly what the chain of events from the ECU -> Igniter -> Coil is

The autoshop101 docs lead one to believe that the dwell is controlled by the igniter...this doesn't seem to hold true for the JZGTE igniter

Answer: JZGTE igniter is DUMB; easy to use on an aftermarket ECU!

Cheers
Wilbo

[sideshow]

most ignitors just have an earth trigger then it trigers the coil to an earth

so it should be ok to use a 2j ignitor

they are all dumb ignitors and have a fixed dwell
u then adjust dwell on aftermarket ecu usually depending on coil or amount of coils u have

[wilbo666]

I know how the ignitor works.

What I was trying to establish was when the ignitor started it dwell time period from! (the falling edge of IGf? or the rising edge of IGf? or ?)

And yes 2JZGTE ignitor is the same as 1JZGTE ignitor.

If the ignitor does have a fixed dwell then you would simply need to know when the ignitor started its dwell period from and then you could account for this in the aftermarket ECU (as a subtraction or addition to the wanted timing). If it is variable it is prbly not worth bothering

Can anyone else confirm that the dwell period is fixed?!

btw in my terminology I consider a 'dumb' ignitor not to control dwell at all...

Cheers
Wilbo

[sideshow]

why the fuk do u want to know when it starts and stops

on a microtech u can adjust the dwell depending how much load is on the ignitor

more coils then u adjust the dwell it is one fixed setting throught out whole rev range

i do know that some bosch coils put more load on some ignitors and have seen ems ignitors fail when fitted with some coils after afew weeks or months of use

an ignitor is just like a signal amplifier
weak signal from ecu gets upped to strong signal to trigger coil

here is how i use an ignitior

i goot shop and buy a bosch 008 ignitior

i wire it up to an autronic or a microtech

then i tune th eneigne

thats it its soooo easy

i dont need to know anything else about that ignitor as long as it works

u cant adjust anyhting in them

its all done by the ecu

on the haltech instruction manual for normal every day ingitors they call them

constant charge ignitors so im sure the dwell stays the same

[JustCallMeOrlando]

Spend $115 on a Microtech X4 (or a little more if you want an X6) and let the ECU control the show.

[oldcorollas]

why the fuk do u want to know when it starts and stops

cos it depends on if the ignitor is smart (controls dwell) or dumb (and the ECU must control dwell).
it also depends if the ignitor triggers on the leading or trailing edge of the ECU output.

ie.. if the ignitor is smart and triggers on leading edge, then both the ECU and ignitor are doing dwell, but the advance angle doesn't change... relatively speaking...

if the ECU is doing dwell, but the ignitor triggers on falling edge, then the ignitor starts dwelling when the ECU has stopped dwelling.. and that difference of 3 or 4ms is a big difference in spark angle.....


if you are using the ECU to control dwell, then you are using dumb ignitors.
if you are tuning from scratch, and don't care about the actual advance numbers being input (ie, as long as engine likes it), then you don't need to worry about base advance or what is dwelling.. you just press up and down keys until tuned and ignore any display on screen

i spose not everyone just plugs shit together and hopes it works....
break out the scope and test the triggering

[Mos]

When the ECU wishes to send spark it asserts IGtx in a fashion such as _____|---|_____
I think on the falling edge the Ignitor then starts the dwell sequence and then fires the spark? But this is just a guess, I can't really tell (it could happen differently).

My initial hypothesis would be that while IGT is zero, there is no current passing through the coil. On the rising edge the coil begins charging, and discharges on the falling edge. I'd also suspect that the ignitor is nothing more than a bunch of high voltage darlingtons (which funnily enough fits in with the hypothesis). This also allows the signal on IGT to control dwell time completely.

As you said, scoping the relevant pins will yeild the answer. (I wish I had done it at some stage... now I need to "borrow" a 1JZ )

Mos.

[chris davey]

So what ecu are you planning on using? megasquirt? something else? So you are trying to determine if the stock igniter is dumb and can be used by an aftermarket ecu that can control dwell. I would probably do what Orlando said and buy an x4 or x6 and sell your stock 1j igniter. I sold mine for $100. That pays for a new one just about And you know it will be dumb.

Or just see what other MS users are using.

BTW I don't like the idea that OC had re tuning to whatever the engine likes. It sort of seems like you would be tuning blind. I would much prefer to have everything spot on so that you know that if you want 20deg advance you get 20deg advance.

my 2c

[wilbo666]

So what ecu are you planning on using? megasquirt? something else?

Prbly going to go adaptronic

So you are trying to determine if the stock igniter is dumb and can be used by an aftermarket ecu that can control dwell. I would probably do what Orlando said and buy an x4 or x6 and sell your stock 1j igniter. I sold mine for $100. That pays for a new one just about And you know it will be dumb.

Yep, trying to work out if the stock ignitor is dumb, or at least constant dwell.

I guess I could go and buy a new one, but yeah, then you don't get to find stuff out and stuff

I think it will be an interesting exercise to scope it and find out; for everyones future knowledge!

Cheers
Wilbo

[thechuckster]

Wilbo - do you want to borrow one of my spare ECU's to test/bench drive a spare igniter? I also have a collection of single-channel toyota igniters if you want to do some comparative analysis (to bring out your inner geek)

[wilbo666]

I'll think I'll just whip the cro out on the weekend and test it on the car, the ECU can drive it as per normal

No need to do it on the bench, easier in the car!

I'll post results when / if I get them

Cheers
Wilbo

[1jzracing]

yes you can

an igniter is just a glorified transistor switch, a 5v signal is used to pull the coil wire to earth simple as that and the 1j igniter is just a bank of 6 of them

i have used the 1jz igniter with an after market ecu (wolf) to make over 300rwkw no problems, i set the dwell (charge time) to about 3ms and it worked perfectly

after that i started using a CDI for boost over 22psi

[wilbo666]

ANSWER: The JZ-GTE igniter is a DUMB igniter. It does not control dwell at all.

IGt OFF = GND
IGt ON = +5V

IGt OFF state -> IGc OFF state (IGc=Open Circuit)
IGt ON state -> IGc ON state (IGc=GND)

tlow-high delay = ~36uS
thigh-low delay = ~20uS

English Translation: When there is 5V at the IGt pin then the corresponding IGc pin will be connected to GND. Where there isn't 5V at the IGt pin then the corresponding IGc pin will be Open Circuit.


Ch1 = IGc (300R pullup to Igniter Power ~13.2V)
Ch2 = Simulated IGt input (signal generator)

Cheers
Wilbo

[wilbo666]

Also 1JZ-GTE dwell time...(JZZ30 Auto ECU)

Idle = ~3.6mSec
2000+ RPM = ~2.2mSec



Cheers
Wilbo

[mic*]

Good info Will,

The TSRM for a (Supra) 7mgte describes testing the power transistors of the igniter, and being that there is a few differences, i thought id put it out there to discuss.

Firstly, you only need a 3V dry cell to switch the transistors... So maybe 5V is just ensuring the signal voltage is always high enough to trigger...

Secondly, when you apply the voltage the igniter, it "momentarily" (read:dwell?) earths the 12V supply to the respective coil. It doesnt matter how long you hold the 3V there, the coil is only earthed for the same constant "moment".

Does this make it a constant dwell system?

[Mos]

Firstly, you only need a 3V dry cell to switch the transistors... So maybe 5V is just ensuring the signal voltage is always high enough to trigger...

The transistors turn on based on current flow - the voltage just ensures an appropriate amount of current flows into the base of the transistor (internal resistors will limit this current to a safe level).

Secondly, when you apply the voltage the igniter, it "momentarily" (read:dwell?) earths the 12V supply to the respective coil. It doesnt matter how long you hold the 3V there, the coil is only earthed for the same constant "moment".
Does this make it a constant dwell system?

This does not sound consistent with the idea of just a power transistor - the negative (rather than the 12V supply) of the coil should be pulled low for the same duration as the signal. There should be no "moment" - it would imply the ignitor controls dwell in some way and has additional circuitry inside the ignitor. Can you scan/provide the relevant pages out of the TSRM?

Mos.

[mic*]

http://www.supra.co.nz/87tsrm/Ignition/ignition17.htm

Page IG-17

What i meant was the 12V supply is earthed THROUGH the coil, so it IS the negative side of the coil which is pulled low (earthed) by the transistor - momentarily

The thing is i totally agree with everything you've said, but check out the TSRM...

Im curious enough that im gonna open up the spare 7M igniter ive got just to see whether there is some sort of capacitive discharge circuitry or something to create a set "moment"

EDIT: You'll also notice that coils A & B require voltage at what im assuming is the base of the power transistor which controls coil C, as well as their respective transistor bases, to fire... Makes me think that its more complex than three transistors inside???

[Mos]

Interesting. I'm thinking the term "mometarily" doesn't imply it controls dwell - would have to scope to learn more.
The power supply could be for protection diodes, but I guess it's possible there might be more circuitry in there.

Mos.

[thechuckster]

the extra electronics are probably there to allow the unit cope with a variable power source (think low voltage during cranking).


edit: this is just a wild guess, but the electronics also allow the unit to cope with coil ringing (flyback).

[The Witzl]

If i'm right... then Wilbo has just shown that the *JZ-GTE ignitors control dwell based on their input signal.

Note the third graph in this image below:




This graph would depict the IGt signal from the ECU to the ignitor. The length of time that the IGt signal from the ECU goes low directly represents the dwell time for the coil - ie. the ignitor just mimics that input signal and applies it to the coil, without any changes.

This varies to a "smart" ignitor, which will vary the dwell time of it's own accord.


Correct me if im wrong.