[Gmecm] Bench testing a GM waste-spark DIS ignition

[davesnothereman at netscape.net]

If you're fabrication skill impaired, are you able to trigger the GM 
DIS module correctly?  Bosch trigger wheels which I've seen are 
typically not the 6+1 pulse design used by GM USA.

I'd be working to match sensor and module.  You should be seeing A/C 
signals from the sensor during cranking.  The 7 pin DIS system 
typically fires at rpm as low as 300.

An old power steering pump or water pump could be used as a test 
trigger wheel.  Use a tape measure around the circumference to mark 
notch positions.  In desperation one could use a hand file to make the 
notches.  Spinning the wheel by hand will cause the module to fire 
coils.

The 7th pulse, or "synch" signal, must occur every rotation of the 
crank or the module will not triger the coils.

Zaphod


-----Original Message-----
From: Tomas J. Sokorai Sch. <tsokorai at xperts.cl>
To: gmecm at diy-efi.org
Sent: Fri, 12 May 2006 10:49:29 -0400
Subject: Re: [Gmecm] Bench testing a GM waste-spark DIS ignition

  On Thursday 11 May 2006 08:13, Mike V wrote:
> cobble something mechanical that is powered by a small electric motor 
or
> <?> Befored you so kindly helped me with my project, I was ready to 
go that

I'm glad I could help, and please do tell if you need any further help 
:)

> route. Mechanical solutions to generate test signals aren't always a 
bad
> thing, they are just lower tech.

Mechanical solutions are my last resort, as I'm a bit fabrication-skill
impaired ;)

I'm getting frustrated with this DIS setup. The used DIS module I had, 
was in
fact dead (I opened it, and found one of the circuit wires on the clear 
gel
burnt open), so I bought a completely new module.

And I still can't get it to fire :(

I made some captures of the crank sensor waveform, and it looks right 
and
clean now that I changed to resistive ignition wires.

My only hope is that the sensor output is too low for the module to 
fire.
The BMW sensor has only 80 Ohm impedance, comprared to the 800 from a 
GM crank
sensor ... so the amount of coil wire difference is pretty hefty. In 
fact
with my voltmeter on AC scale, I can't get readings, but for what I 
read, the
GM sensor should put out some average volts that way.
If I can't get it to fire with the soundcard idea, I'm tossing the DIS 
and
keeping the crappy distributor that I can't get a rotor for.


--
Tomas J. Sokorai Sch.
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