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I've been having problems starting my 914F3 engine (vintage 1998, now 600 hrs smoh) at temps below about 45 degrees, just a little warmer and it starts right up. i was quite amused to see that the 914F3 engine cold weather starting spec listed in my 1998 operators manual is MINUS 15F :)

I am almost certain that it's an issue of "no spark" at less than 90 RPM as the neon bulb ignition tester does not light up in these cases. I suspect i have multiple small problems contributing to my woes: old starter, old ignition modules, 10w-40 instead of 5w-40 oil, plug gaps too wide and a two year old battery.


The cheap fixes - AGM battery with high CCA , plugs, 5W oil will probably improve things, but i got to wondering what happens when i'm out in the middle of nowhere and it's 20F(or colder!!) and i can't get 90 RPM for Spark?

>> Seems to me the root problem of cold starts is "no viable spark" at less than 90 RPM.due to charging coils not really supplying enough energy to ignition modules <<

Does that make sense to those of you who know more?

If so, then while an HD starter ( and maybe new ignition modules) would probably help a lot , but those ain't cheap fixes and in the case of the HD starter doesn't really DIRECTLY address the "root cause"

I got to thinking about this and wondered if anybody has ever tried/thought of supplying the equivalent of (>90 RPM) charging coil pulses to one(or both) of the ignition modules during engine start.
  • Re: Root cause for Cold weather starting woes?

    by » 7 years ago


    Some things that might make your engine spin faster during starts:

    1. Lithium battery
    2. Larger cables (4AWG) in the starting circuit
    3. Solid crimps in the starting circuit
    4. Clean, tight connections in the starting circuit

  • Re: Root cause for Cold weather starting woes?

    by » 7 years ago


    The gold colored higher torque starter does make a big difference. I had a plane many years ago that had you same symptoms and the new starter was the ticket.
    If you live in cold country I would also install a Tanis engine pre-heater and have the engine up in the 70F - 80F range along with the oil for easy starts.

    Use a narrow vs wide plug gap will help. Making sure the carbs are well synced. A good battery.

    A cold engine and the old starter are your two big problems. Carb sync and battery are easy to fix.

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


  • Re: Root cause for Cold weather starting woes?

    by » 7 years ago


    Ken, some good thoughts to add to the list of little things that eventually add up!

  • Re: Root cause for Cold weather starting woes?

    by » 7 years ago


    Roger,

    Trying the narrower gaps (.6mm) tonight we'll see how it goes.

    Good to know starter makes a big difference , Maybe Santa will bring me a new starter :)

    Do you have any comments regarding the reasons for no spark at less than 90 RPM@ prop....is it likely lack of energy from charging coil?

    Peter

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