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

[Tomas J. Sokorai Sch.]

On Saturday 13 May 2006 00:35, davesnothereman at netscape.net wrote:
> 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 already did the trigger marks on the front cranshaft damper.

I "can" do at least some fabrication :)
I already did a sucessful 1975 Ford 302 conversion from carb to TBI EFI (TBI 
intake adapter, fuel reservoir and some other small stuff), but for example 
doing the 6 marks (the damper already had the TDC mark for delership 
diagnostics) took me a whole day, so I try to avoid everything that involves 
fabrication, machining, etc if there's an electronic or software way of doing 
something ;)

>
> 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.

I was trying to get it to fire with the original diagnostic TDC sensor. 
According to the "scope" (a PC soundcard line input capture), the waveform 
looks right, but I think the signal is too weak for the module.

I wrote a little program to simulate a 6+1 crankshaft pulsetrain at any RPM 
with the soundcard output, but I couldn't test it over the weekend as I was 
away from home.
BTW, 2 crank degrees for each AC wave from the sensor sounds about right for a 
simulation, right?.

>
> 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

for the damper marks, I did a whole CAD template of the damper and the marks 
for getting it 100% right :)

-- 
Tomas J. Sokorai Sch.