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Ignition Module Problem

in 912 / 914 Technical Questions 13 years ago
I have a 912UL with 140 hours. Noticed engine was running a little rough at idle (1800-1850rpm). Normal shut down proceedure is to turn off the B module followed by the A module. When the B module was turned off engine shutdown, further investigation indicated the A module not functioning at idle.
I then did an ignition check at 4000 rpm and observed the following: With B Module off 160 rpm drop.
with A module off 0 rpm drop. I checked the ignition switches and wires to the modules and found them to be functioning normally. I have started looking for broken wires but have found nothing at this point.
Has anyone encountered this issue and were you able to detemine a cause?
Does anyone know of a ground test method for the ignition module?
Any suggestions would be helpfull.

  • Re: Ignition Module Problem

    by » 13 years ago

    When testing ignition modules (not Rotax) in the past I have used a signal generator to generate inductive pickup timing pulses to trigger the ignition pulses with a static engine.

    Since the rotax ignition packs are powered from the rotating engine you will also have to make some provision for a permanent supply. I am sure that something could be rigged up with reference to the Rotax manual.
      
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  • Re: Ignition Module Problem

    by » 13 years ago

    Hi Mike,


    Broken wires and poor connections at the connectors are many times the culprit. Put a hand on every wire and plug and unplug each connector. Many have thought they had a part problem when it turned out to be a broken or chafed wire. Pull lightly on each wire coming and going out of a connector.
    The Heavy maint manual has a section to help diagnose these problems. You will need a multimeter for ohms and the such and you can check the different connections like the trigger coils and other connections.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell

      
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  • Re: Ignition Module Problem

    by » 13 years ago

    so far I have checked for broken or chafed wires. Checked connectors for lose or poor contacts. Made sure ground wires were making good contact. Have not found anything yet. Currently working through the heavy maintenance manuals ignition maintenace/troubleshooting section.
      
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  • Re: Ignition Module Problem

    by » 13 years ago

    mike,
    how did you get on. I have a module here which is suspect but I cant find a good way to test it.
    Dai
      
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  • Re: Ignition Module Problem

    by » 13 years ago

    Okay guys, I'm a new member here and joined because I just bought a Rans S-7 with a 912 Rotax that has the "Extra-Performance" piston kit installed. I am having the same issues as the original poster.

    I was doing my run-up today to go flying. The engine seemed to be running rough and sure enough when I did the mag check, the motor quit on one of the mags. It was completely dead. The builder put in two toggle switches to check the mags and I swapped the leads so I know it wasn't the toggle switch. During mag check switch #1 allowed the engine to run while switch #2 did nothing. Engine was only running on mag #1.

    I swapped the 4-pin plugs on the Elctronic modules and then it worked on switch #2 but not on #1 so I am figuring the module is bad.
    Is there any way to check this module? Sort of sucks since I was hoping to fly to a couple of flyins this weekend.
    Oh, the motor only has 150 hrs. TT

    Does anyone have an idea where I can get a replacement for less than giving up my first born? The price for a new one is utterly rediculous!!! There is no reason what-so-ever for it to be priced close to $1,000!!!!! Pure greed from Rotax. I am starting to hate this engine already after flying for 25 years behind Lycs. and Cont. that just keep chugging along. Okay, I'll get off my rant.

    Thank you,
    Keith
      
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