GM DIS EST Wiring

[NeedTurbo]

Hi,

I'm running MS-II on a L61 ecotec.
It has a 7x (6+1) crank trigger.
Im using a Gm Dis ignition module from a an older 2200 sohv 7x.

When running with the Est line disconnected I read 29 deg advance.
This resulted in a trigger offset of 83 with the digital timing light.

I want to remove the relay that is used inline with the Est wire.
A friend of mine had a relay die with this setup. It ran the high advance under boost and detonated the crap out of an engine.

So I simply removed the relay.
Problem is that it takes forever to start now.
I thought maybe adjusting the skip pulses to a higher amount would fix it,
But it did not.

Any advice would be apreciated.
Thx

[Matt Cramer]

Try using one of the spare LED outputs to send it 5 volts when above cranking RPM.

[NeedTurbo]

Yes this would work,
But it's not really what I was asking.
I already have a bountiful source of hot on run, but not crank lines .

I would like to eliminate the relay completely.
Is this possible?

I liked the idea of using the skip pulses (as I've read that this is the delay in tach pulses before ms will send a calculated advance signal)
So if there's a skip pulse delay of say a ridiculous number? 2000 would this not result in ms waiting 2000 tach events before sending a signal over the EST line?

Or is the skip pulses referring to "Calculated" advance, such as spark map vs iat adv, vs cold start adv, ect....

To clarify I thought It meant that ms will not send any signal what so ever over the est line until the skip pulses was fulfilled.

Again,
Thx for the help.

[Matt Cramer]

The skip pulses also turn off fuel.

You can modify the MS to send 5 volts to the module directly, without a relay.

[NeedTurbo]

I think maybe were thinking about two dirrerent things.

As far as i know, I don't need a 5v going to my ignition module.
That's not what what I'm asking about either.

The EST line I am referring to is the line that allows ms to controll the timing of the ignition module.
Once the ignition module recieves a signal from ms, it will run the advance ms tells it to.

My problem is when the EST line is disconnected (ignition module running independent of ms) it will run 29 deg advance at all time.
I do not like the idea of having a relay inbetween that line.
If the relay is there for starting/backup purposes I would like to find a way to remobe it,
and run the est line straight from MS direct to the ign module.

This is just a temporary fix mind you.
I plan to run an external trigger and have ms decode that.
As I'm not 100% pleased with the results from this Dis module.

It's funny that you mention that skip pulses also cuts fuel.
My starting problem may just be a result of raising that.

Thanks for the help,

[Matt Cramer]

Does this module have a Bypass pin? I was thinking of the modules that have a B pin that accomplishes its own "disconnect" feature - the module ignores the EST signal unless it gets 5 volts at the B pin.

[NeedTurbo]

Ohh your talking EDIS,

I'm working with GM DIS.
The module i have has the exact wiring schematics as under megamanual for gm dis.
Except for it has 2 power sources instead of 1.
I'm pretty sure I'm using an equivelent to
Standard Motor Products LX345
Though it could be
Standard Motor Products LX981.

The module sits under 2 dis coils.
Vr sensor plugs in the a pigtail, unlike the edis.

Anyways, I'm able to start the car now with the bypass relay completely removed.
Oddly enough setting the max cranking speed to 250 rpm helped. Not sure why. I didnt try lower.....
Maybe my cranking pw's are to high? 11.5,3.4
Skip pulses back down to 3...... lol
It's not perfect yet tho....


could it be that the module is getting a advance signal to early from ms, and thats screwing poop up somewhere?
OR maybe I have to re- tune my cranking pw's as my cranking advance used to be like 29.
cuz under the cranking portion of my spark map it wont go above 17.....
That might be the problem if ms is infact controlling the timing during cranking....

Lol any ideas?

[Matt Cramer]

EDIS does not have a bypass pin. Do you have the year and model you took that module out of? I can't look up wiring by part number but I can check by year and model.

[NeedTurbo]

Aw man....
I'm such a door knob...
lol..

Ok so you were right...
There is a 5v going to the module...
This is the bypass line.... when the module sees 0v it uses it's timing.... when it sees 5v it uses ms's timing...
This is where I used to have the relay.....

I'm using the 5v ref that's normally used for the tps.
So right now my ignition module is getting 5v in crank and 5v on run as I removed the relay....
I used my factory pcms 5v ref for the tps. (if you were wondering if I split it.... I didn't)

Is there a way to program this "tps" 5v ref? I'm assuming not...
But I can always do what you suggested and use a spare port, or led..



I've got so much stuff going on that I must have forgot how I wired the fricking thing....
Sorry about that.

It's a Dis module from a 91 Sohv 2200 cavalier.

[jts749]

i just wired the 5v ref through a switch to the dis module on my saturn
and mine is split between the tps and the dis
everything working fine here