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Right-O on the difficulty of long distance diagnosis.
John did tell me that the threshold of 'splutter' was around 38" Hg
MAP. Since the engine quickly went down hill even at lower throttle
settings and he thought it was only running on one rotor at the end of
testing, I suspect there are a lot of clues to what is wrong other than
the 'splutter' at 38". We just don't know what they are. The
coils being bad is a long shot since it would mean that two of them died at
once, not likely but possible.
Sermon follows:
Guys, Learn to be very sensitive to your engine. Know
every nuance of its character. If you don't know what the air drifting out
of the inlets after shutdown smells like, you aren't paying enough
attention.
Tracy
----- Original Message -----
Sent: Tuesday, May 23, 2006 7:45 AM
Subject: [FlyRotary] Re: Another case of
heat-soaked coils?
John, Not being there makes it hard to make an
assessment. Anytime I have
had an engine spitting and popping it
either mean the air/fuel mixture was
too lean or I had a ignition problem
(mainly timing). I have no experience
with any coils other than the
stock Mazda but additional cooling certainly
could not hurt. It
really sounds like to me your engine is increasing rpm
until its getting
into a region where the air/fuel mixture may be too lean.
Normally a too
lean engine will pop and spit but not certain if your sputter
is same as
my sputter {:>). Also you did not mention what boost levels you
were running when this was happening.
Ed
Any time my
engine acts abnormal, its grounded until I figure out the
problem
-----
Original Message -----
From: "John Slade" <sladerj@bellsouth.net>
To:
"Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent:
Monday, May 22, 2006 9:56 PM
Subject: [FlyRotary] Another case of
heat-soaked coils?
> Yesterday I took a friend for a ride and
the engine purred sweetly for the
> entire trip. Looking back, the only
thing different was that there didn't
> seem to be an rpm drop when I
disabled leading or trailing coils during
> the runup.
>
>
Today all was normal during runup (except perhaps the coil disable causing
> no rpm drop) and full power got me 5300 before I couldn't hold it any
more
> on the brakes. Take-off and climb were normal. On the downwind I
was
> showing 5800 rpm so I decide to coursen the prop. When I did I
felt a
> splutter. I reduced throttle and the engine ran normally. I
increased
> throttle. More splutter. I reduced throttle and it ran
normally at 4600.
> Any more throttle and all I got was reduced power
& popping and spitting.
> I circled the field trying mixture
adjustments, checking fuel pressure on
> both pumps, coil &
injector defeat and swapping to B computer. Nothing
> seemed to make
any difference, so I landed.
>
> The only change since the
previous flight was that I'd replaced the plugs
> with a clean set -
not new - just clean. Suspecting a bad plug I let the
> engine cool
down a bit, then installed new ones. Later in the day the
> engine ran
fine during taxi and again reached 5300 on runup. Acceleration
> seemed
normal then, halfway through the takeoff roll, I felt a splutter,
> so
I aborted and rolled off the runway.
>
> When I added power to
taxi clear of the runway the spitting got much
> worse. So bad, in fact
that it seemed to be running on one rotor and there
> was insufficient
thrust to move the plane forward. I tried adjusting
> mixture and
defeating injectors & coils again and the engine eventually
>
stopped. I was able to restart, but had the same symptoms. The rpm was
> fairly steady at 1100 or so, but this was the max rpm I could get.
The EM2
> was flip flopping rpm readings 2300...400...2100..800...every
couple of
> seconds.
>
> I called Tracy from right there on
the taxiway. As always - he took the
> call and listened to my
unscientific whining. Thank you Tracy :) Anyway,
> his best
thought was that it sounded like it might be a coil heat-soak
>
problem. It definitely seems heat related, and my cowl has been running a
> bit hotter since I installed the new T04 turbo.
>
> I
pushed (yes pushed) the plane back to the hangar, then tried turning the
> prop to feel all six compression strokes. To my untrained arm muscles
the
> compressions all felt the same. I ordered 4 new coils and will
report if
> this corrects the problem. Whether it does or not, I see a
separate air
> duct for the coils in my future. The blow tube I
installed may not be
> providing enough cooling. I once tried
installing a temp sensor at the
> coils, but this sent other EM2 temp
readings haywire - induced current
> from the ignition? - so
unfortunately I don't have temp readings on the
>
coils.
>
> Anyone have additional thoughts on
this?
>
> Sincerely,
> Frustrated in Florida (I could add
another F at the beginning to help with
> the .ing alliteration, but I
won't)
>
>
>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive
and UnSub: http://mail.lancaironline.net/lists/flyrotary/
>
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