why i can't cheat dump ignitor?

[CHB]

i've tried to make connections so that my MS2 controls my ignition. i've use my MS2 using negative coil triggering for quite sometimes and now i've decided to make it fully controlled by MS2.

i disconnect the coil negative wires and connect the ignition output from MS2 so that it will run "Direct coil control". fine, then i've connected a 1Kohm resistor across the +12V to the ignitor's negative control wire(so that the ignitor still assume its controlling a coil) but then it was nothing happened on the datalog, no RPM was detected. how could this be?
any one has any clue how to cheat this Ignitor so that will will still acting like grounding a coil so that i can get a clean signal to my MS2 like previously does?

[The Real Roadrunner]

doesnt the ecu get a signal from the CAS? then an output to the ignitor to control when it sparks?

ive never used a resistor across an igniter and cant think of a reason why you would need to.

[thechuckster]

lindon: he's using the igniter as a VR interface to drive the ECU. Am assuming the resister is there for testing purposes only.

CHB: what igniter are you using? and what version ECU board are you using (2 or 3)? You're still going to use the igniter to drive the coil?(as per the ms2/vast diagrams linked to below?)

I use a VR interface board (is a home-brew thing - based on the LM1815 chip) rather than trying to use the toyota igniter for 2 purposes.

some useful reading:
http://www.megamanual.com/ms2/vast.htm

[CHB]

i no more using toyota ignitor to fire the coil as i'm using on board VB921 to do the task. btw, i'm using MS2 V3.
at first i didn't connect any resistor across the terminal, just directly run negative control wire from the toyota ignitor to MS2 V3 tacho input, no RPM was registered.
i think come across an idea, connect a 1Kohm resistor from +12V to the negative control wire from the toyota ignitor, this means that the ignitor will take the resistor as a coil, which it will fire normally but this isn't the truth, still no RPM was registered.
then i tried the 3rd method, keep the stock ignition coil and the ignitor in place but disconnect the high tension lead to another toyota "dry" type ignition coil. this dry coil gets +12V and another wire go to Pin #36 of MS2 V3. the car will fire up at once.
now i'm tying to get rid of the bulky oil filled toyota coil, but i can't as the stock ignitor needs it to generate tacho signal.
any other idea?

[thechuckster]

Seeing as you're only using the igniter for a tacho driver, i'd recommend this circuit anbd dump the igniter - this is used with a lot of success:
http://img366.imageshack.us/img366/7...mulator4ly.gif
and this is also recommended is this circuit on the MSextra site:
http://megasquirt.sourceforge.net/extra/tachopin.html

all it needs is a diode, a transistor, a gutted relay and a resistors - will fit inside a relay case if made creatively. Allows you to use the tacho out from the ECU (assuming that you are running extra code with has a tacho out pin)

btw: kudos to wilbo for original posting of circuit.

[CHB]

refered to the diagram below,

where should i get my 5V square wave from?
now my problem is cannot get RPM input into MS2, not RPM output to RPM guage.

[Chrisso]

I've just finished my MS2 using the onboard coil driver. I would check with Chuck or one of the other guys, but if I've understood correctly, your input should be sourced from your CAS (VR input).

Not sure whether this is entirely applicable to you, but do you have the right jumpers on the board ie. igntin, js10, and igntout?

Chris

[CHB]

yes everything works perfectly if i keep the ignitor with the coil(even though the coil is not use for ignition, it just have to be there together with the ignitor to make the coil negative signal works).
VR input is prone to have noise interference from other electronics devices. that why i would like to "condition" my VR signal before fed it to the MS input. since i've run with success trigger the MS2 from coil negative, i think it is better to have the signal "conditioned" before fed it to the MS, then MS will fire the ignition coil with advance and retard.

[3jcelica]

CHB,

I am using the toyota ignitor as a tacho input to the MS. I was originally using a GM HEI but the signal wasn't great. In the end I figured that you can either build the LM1815 interface as described by thechuckster or just use the toyota module out put (that would normally go to coil -ve) and wire that into the Taco.

As the ignition module was redily avaliable (had a couple lying around and cost ~$5 at the wreckers) I used this and the signal has been fantastic. The only difference I have made to the wiring from a stanrd use of the module was the coil negative(black wire) to the MS tacho input. I did not use a pull up resistor on the module output as you have described (maybe I should) but the signal has not been better since I used the toyta module.

My ignitor is off a 22re but I assume it would be almost if not identical to the one you are using. I am using a V2.2 board but I can't see there being much difference

[CHB]

yeah i was wondering why i can't make it work with wire that normally go to coil -ve. any one can give me any more clue?

[CHB]

CHB,

I am using the toyota ignitor as a tacho input to the MS. I was originally using a GM HEI but the signal wasn't great. In the end I figured that you can either build the LM1815 interface as described by thechuckster or just use the toyota module out put (that would normally go to coil -ve) and wire that into the Taco.

As the ignition module was redily avaliable (had a couple lying around and cost ~$5 at the wreckers) I used this and the signal has been fantastic. The only difference I have made to the wiring from a stanrd use of the module was the coil negative(black wire) to the MS tacho input. I did not use a pull up resistor on the module output as you have described (maybe I should) but the signal has not been better since I used the toyta module.

My ignitor is off a 22re but I assume it would be almost if not identical to the one you are using. I am using a V2.2 board but I can't see there being much difference

wait, may i ask if you configure your ignition input as Hall input or coil negative? i've done coil negative method on my V3 board, could it be the cause?

[thechuckster]

the igniter probably expects some kind of load across the coil - it's normally only a few ohms and obviously inductive.

fwiw: i use a VR sensor (from a 22RE) and take it all the way into the cabin via about 5 foot of shielded cable. Neither the VR sensor pair of wires or the shield is earthed at the dizzi. In the cabin, i take the VR signal and signal return to the LM1815 circuit and the shield on the cable is grounded with all the other ECU signal grounds.

To get the 5V square wave output, i use pin X2 on the board (i have a v2.2 board) - but more importantly, i'm running Extra code not standard B&G code as at the time only the Extra code supported a tacho out signal at the ECU.

This is rough schematic of how i wired it up: