7MGTE Ignitor Operation & Alternative Ignition Coils

[grimreaper]

^ essentially yes, but with a twist. The coil start to charge, or on signal has to be generated completely. Nothing in the stock ecu will work for that. Thanks for the support. I hope to see it through as well!

The BOM is not finalized yet. I started with the well known atmel 328p used in the arduino uno. The arduino IDE is limiting in this projects scope though due to the way they invoke pin states/changes etc. Extremely slow compared to direct port manipulations! Timing is critical on this setup! The code is in arduino and standard C for atmel studio. Right now Im using a 328p TQFP package and will most likely stick to the 328 or change to the attiny84. I havent worked out programing the dwell table without the ISP yet. Most likely some form of led position indicator followed by a a dip switch input. My biggest concern is fine tuning the way things start up and adding error correction for massive timing changes. When the ecu goes from 12 degrees at idle to 45 degrees at low load/2000rpm, the desired dwell is cut short. We are always one step behind the ecu and thats hard to overcome! The stock ignitor gets away with it because it current limits and provides ample time for the coil to charge.

Ive been debating making this open source and posting all there is so far. There would have to be enough support on the coding side to make that doable though. I can handle the board layout but if someone is capable and had the time id be happy to open up that portion too. The specific caps need to be selected with considerations for the regulators esr. TVS protection is covered. transistors or a transistor array needs to be selected, 6 total. correct biasing for those and then putting it all together with the mcu. Plan was to keep as much as possible in surface mount packages.

Piratetip if those are areas your into, feel free to pm me and we'll talk, or anybody else for that matter.

Here is the proto board Ill be using to finish out the code tweaking. Waiting on transistors and a few resistors + external wiring. That small square chip in the center is the 328mcu, its smaller than a pencil eraser. Damn amazing how small things can do so much! Hope to be running on a new ignitor +stock coils this week or next!

 

[Piratetip]

Nice work.
I used the same platform.
Wanted to downsize it to an attiny but never got that far.
Would be beneficial for reducing costs on the hardware.
Need a good stable power supply for the microcontroller, automotive power is pretty unstable/dirty for them.

 

[supraguy@aol]

The BOM is not finalized yet. I started with the well known atmel 328p used in the arduino uno. The arduino IDE is limiting in this projects scope though due to the way they invoke pin states/changes etc. Extremely slow compared to direct port manipulations! Timing is critical on this setup! The code is in arduino and standard C for atmel studio. Right now Im using a 328p TQFP package and will most likely stick to the 328 or change to the attiny84. I havent worked out programing the dwell table without the ISP yet. Most likely some form of led position indicator followed by a a dip switch input. My biggest concern is fine tuning the way things start up and adding error correction for massive timing changes. When the ecu goes from 12 degrees at idle to 45 degrees at low load/2000rpm, the desired dwell is cut short. We are always one step behind the ecu and thats hard to overcome! The stock ignitor gets away with it because it current limits and provides ample time for the coil to charge.

Ive been debating making this open source and posting all there is so far. There would have to be enough support on the coding side to make that doable though. I can handle the board layout but if someone is capable and had the time id be happy to open up that portion too. The specific caps need to be selected with considerations for the regulators esr. TVS protection is covered. transistors or a transistor array needs to be selected, 6 total. correct biasing for those and then putting it all together with the mcu. Plan was to keep as much as possible in surface mount packages.



View attachment 71745

Well, of course. I was going to suggest most of this...

:icon_eek::icon_eek:

 

[satx88supra]

Maaan my head is smokin!!! But i hope this comes together.

Sent from my MoPho

 

[karlou426hemi]

Hi

I'm now working on a 1jz vvti swap in my mk3 and found something interresting with the dh61 igniter
I'm using MS3x as engine management and i found the igniter would not let me run the dwell i desired.

To find the optimal dwell time for the strongest spark i removed plug 1 & 6 and connected them to coil 1 and ran test mode in the megasquirt to visualy inspect the spark. I found that going from 2ms dwell to 3ms would give a really stronger spark but going from 3ms to 4ms wouldn't change spark that much so i setted dwell time in the MS3 to 3.5 ms. the ran test mode up to 12000 RPM witout issues or less stronger spark.

Here's my problem: when i started the car i wasn't able to rev to more than 5000 rpm and it seemed like i had spark problems(like spark blowout at high boost). so to be sure it was related to ignition i decided to unplug the alt to run with lower voltage and now it would not go past 4300RPM so i knew it was a spark related problem.
After that , to make things short i started to play with my dwell setttings. I realized that the more dwell I had, the less high it would rev. To rev to my rev limit of 8000RPM i had to put a dwell of max 2.5 ms so ended up running 2.3ms of dwell.

I don't know if somebody have experienced the same things with the dh61 but it really piss me off because i plan on running over 30psi and I'm already starting with a weak ingnition since I can't fully charge the coils.

Looking foward for more info about the DH61 ignitor limiting Dwell, and if it does the same thing as the 7mgte ignitor and dwell is limited by current then why changing dwell in my MS3 affect spark intensity ????

 

[grimreaper]

bit of a redirect. The short coming of the 'one step behind' operation is hard to get around. 3p has a viable solution, actually two. The easiest being to mimic the stock ignitor and provide ample time to charge. Basically redoing the power side and changing the current limit the ignitor will allow. The stock igntior has a construction I have never seen before. A few places on line list it as a thick film. The passive components appear to be printed onto the pcb. Think resistive 'pad' like you find in trim pots or the 7mge flapper style vane flow meter.
Thats the best i have so far.

Soo back to the drawing board a bit. Not sure if the MCU i have been messing with will survive the final BOM. The analog side is slower than I would like. Right now Im playing a bit with different op amp setups. Thinking of an op amp controlled current source feeding a BJT or possibly IGBT. ST mirco has a nice line up of ignition IGBT's so there's an option. My nose is back into the books sorting all the details out. More to come..

Karlo.. i wouldnt be surprised if all ignitiors from toyota/denso have some form of current limiting involved. A short circuit would fry a rather costly component. Most of the tech papers in the tsrm show a lock up prevention inside the ignitor. Maybe this is what your hitting? anything over a preset dwell is considered lockup and the coil fires? Do you have a scope to look at the coil primary voltage?

The 6 channel ignitor I have is not a dumb one either. It appears to calculate the dwell angle separately from the ecu.. and reportedly doesnt work well in waste spark configuration..

 

[karlou426hemi]

Nope I don't have a scope but your theory seems good. Anyway if i have ignition issue i will just find a ''dumb'' 3 channel ignitor that will let me charge the coils a little bit more...

What would be the best 3 channel dumb ignitor?? (just in case the dh61 is not up to the task)

 

[Rollus]

May I bump your thread Grim ?

Your car is for sale, that's a bad news for this project I guess.

BTW, I will upgrade my ignition system, and maybe I could continue your development if you stopped
I have some arduino nano, micro, and due laying around

++

Reynald

 

[grimreaper]

Hey Reynald, Shoot me a pm if you want to take a look at the code i wrote. No sense in starting from scratch! Please do keep this going. I moved things over to atmel studios 6 too if you are familiar with that.

Current limiting of the ignition coil is the only real hurdle I can forsee. I dont know if PWM is possible. I was worried any open circuit would cause an unintended ignition event. This led to the op amp controlled BJT for the power stage.

The code should take care of coil identification and coil dwell window. Plus coil firing.
The current limiting needs to be sorted and then hardware.
I cascaded two linear regulators for the powersupply. I spent a good amount of time selecting them so ill get the part numbers and share them.

Ill be out of town over the weekend but will try and post all i have next week or so.

 

[supraguy@aol]

Are you bowing out of the Supra game entirely, Grim?

 

[Rollus]

Grim, all (piratetip?),

I would love to take this project over and keep it going .
I don't know if I will be skilled enough to fine tune the code with atmel studio but can have a look.

I'd like some people to join me to help. Piratetip, would you like to join?

Grim, I'd like to receive project files @ supra_at_reynald-rollet.fr please, and anyone willing to join can mail me this adress also.
If I can continue this project, I'll set up a github or bitbucket repository to host and share everything (privately or publicly depending on Grim wishes).

BTW, as supraguy asked: are you bowing out of the Supra game entirely, Grim?

 

[Piratetip]

Sure Rollus.
I will lend a hand on this project.
Would love to see it through to completion.

 

[quickstudy]

Just an idea for the group:
Why not use three 7m-GTE ignitors wired to a piggy back with ignition function like Emanage Ultimate? Just preset each to trigger one channel each time by sending IgDA to one, IgDB to the other, and and both to the third ignitor, then use different EMU ignition channels to sent an IgT signal to each ignitor. Then you can control the timing of each channel separately, get the dwell adjust function from the ignitors, and be done in an afternoon.

 

[KKZ SupraMan]

Just an idea for the group:
Why not use three 7m-GTE ignitors wired to a piggy back with ignition function like Emanage Ultimate? Just preset each to trigger one channel each time by sending IgDA to one, IgDB to the other, and and both to the third ignitor, then use different EMU ignition channels to sent an IgT signal to each ignitor. Then you can control the timing of each channel separately, get the dwell adjust function from the ignitors, and be done in an afternoon.

GREAT SCOTT Marty +1 for flux capacitor setup with this also lol but on a side note this just mite work now to the drawing board great thinking

 

[grimreaper]

Hey guys, Rollus has the code i started with the interrupts and timing calcs in it. Feel free to make use of it as you please. If any one wants a copy, pm me your email address (piratetip).

I still have the bench top setup to demo on so I am happy to continue that portion of the project. Car sold a few weeks back to a forum member.

Other wise...
Three ignitors or two doesnt matter. The dwell time is calculated by the ignitor. Im not understanding why controlling the timing for each channel is necessary.

 

[quickstudy]

Thanks for clarifying the goal of controlling dwell time. Of course that needs replacement of the internal circuit.

 

[supraguy@aol]

In a configuration controlled by the stock ecu, is a DH61 igniter a viable option?
And if so, is there any benefit to it over the original igniter? I was never clear on this.

 

[andrew_mx83]

Ive been trying to use the 7m-gte ignitor in a non-standard setup recently and thought i would post up my observations:
Engine is a warm 7m-ge with Ford dumb COPs and MS3x megasquirt management running in Waste COP mode. I wired this up with the 7mgte ignitor as thats what came in the car (which was delivered as a gte). MS has a 'toyota multiplex' option for spark output/dwell control which i was using.
Removed a coil to test for spark and observed spark. Then spent a week trying to get it to fire with no luck. Turns out under cranking load i had no spark, or it was getting blown out. Changed to 7mgte coils and it fired first go. I now observe a MUCH stronger spark in test mode.
Conclusion- the 7mgte ignitor will not fire the Ford coils correctly (at least off a megasquirt)
I got an RB25 ignitor and suddenly observed much stronger spark in test mode, but still no fire on Ford coils.

In order to get the MS timed to the engine correctly when using the 7m ignitor i had to change the missing tooth offset setting on the crank trigger from 60* btdc to 300* btdc. Still being 60* off TDC i didnt think much of it.
The engine ran with this INCORRECT setting and timing was verified with the timing light as being correct.

BUT!! With the RB ignitor the engine would not fire on this setting, sounded like timing was waaay out. I connected the timing light again and now the trigger offset needs to be back at its mechanically correct setting of 60* btdc
Conclusion- the 7mgte ignitor introduces a delay, or works ahead 120 or 240* from when the ecu sends a firing signal (IGT) until it actually fires the coil
Conclusion 2- the 7mgte ignitor is a bastard of a thing.

Im sure most of this was covered in the OP, but im still trying to digest all that (electronics aren't my strong point)
Hopefully some of these observations can help someone else in future trying to get theirs working.