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I certainly agree with Tracy. Get to know
every nuance of your engine. How it feels, what the vibration is like,
what does it sound like at 3000 rpm, how does your EGT respond to throttle
movement, what does the exhaust drone sound like, etc. I must admit I
haven't sniffed the intake air, yet - but, I'll try that next time
{:>).
Ed
P.S. You'll have to make a return visit with Laura
before the secret of the Gin & Tonic concoction is revealed
{:>)
----- Original Message -----
Sent: Tuesday, May 23, 2006 9:22 AM
Subject: [FlyRotary] Re: Another case of
heat-soaked coils?
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)
>
>
>
>
>
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> Homepage: http://www.flyrotary.com/
>
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