[Diy_efi] FW: [fangle] Testing an inductance coil.

Tue Aug 16 13:44:45 UTC 2005

Your system might operate like the digital GM system. If the MAF is not working , the injectors won"t fire.  My 95 Aurora
engine wouldn't start, had a MAF code, unplugged the MAF and it started fine, plugged the MAF back in no Start.   

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]
Sent: Monday, August 15, 2005 9:25 PM
To: diy_efi at diy-efi.org
Subject: [Diy_efi] FW: [fangle] Testing an inductance coil.

What I want to test is an inductance coil.  I purchased an analog AirSensors EFI unit over a year ago[Joe Boucher]  at a swap meet .  The kid told me the entire kit was there.  However, the temp sensor was missing.  A week ago I found a source for the part.  So, I started testing.

There are some LED's in the box indicating if certain functions are working.  The only inputs are the mass air flow sensor, temperature, ignition on, tach signal from coil, and an inductance coil wrapped around the second firing spark plug wire.  Outputs are fuel pump power, an optional fast idle signal, and the four injectors.

I'm not sure if the inductance coil wrapped around the wire is working.  All the LED's went out, but the injectors didn't fire when I hooked up the tach and inductance lead to the Camaro.  The coil has to be oriented properly to the wire and I think it was correct.  Didn't have time (and the idea) to try swapping the coil.  The diagnostic trees in the manual list the coil has a requirement for firing.  I think.  It's not a great manual.

I want to test the coil.  All I have is a multi-meter.  It does have a frequency function.  I used it to test the tach signal.  There was a frequency that increased and decreased with engine speed from the tach signal.  Can I use the frequency meter to see if there is a signal [Joe Boucher] from the spark plug coil without destroying the millimeter?  Or should I set the meter to AC and 20K volts and see if there is a signal?

The injectors are fired like most with the ground bring controlled to pulse the injector.  While the unit was "on", there was not 12 volts at either of the lines into one of the injector plugs.  One initially showed a signal but the voltage quickly decreased to 0.  That doesn't seem good.  I will admit the connection to the 12 volt power source was suspect, so I will do a better job for the next test.  

My plan is to try the test again, see if the inductance coil is working, try flipping the coil, and see if there is voltage at the injectors.  If not, the next step is to open the box and see if I can spot where the magic smoke has escaped.

Thanks for any help.

Joe

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