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Thanks for the feed back, Perry. The lead fouling is the cause of our SAG, but with the stock plugs I used, I generally get 20 hours before SAG starts. But, as in your case, it will continue to get worst until you change spark plugs - did I ever tell you how many used spark plugs I have waiting for a good lead cleaning solution? {:>). I fly mostly with 100LL and found that so long as I change the plugs ever 20-25 hours no SAG, might get to 30 hours, but Tracy reported gets close to 200 hours on a set of plugs using Mogas.
Going to try some of this Hobbs #9 gun cleaning solution that I have heard removes lead and see if I can just soak them in it and get at least 40 hours off of a set.
Sounds like a neat way to control the mixture on the stock auto CPU. Just put a potentiometer in the circuit and ala! a mixture control. Let us know how it works out.
Ed A
----- Original Message ----- From: "Perry Mick" <pjmick@mail.viclink.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Tuesday, January 17, 2006 12:34 PM
Subject: [FlyRotary] TCP Doesn't Work?
>Hi Perry,
Disappointed to hear that TCP did not work. May I ask "in what regard?".
Did the O2 sensor degrade? - SAG occur?
I purchased this product (Decalin) appears to function similar to TCP and
I noticed they say to clean the O2 sensor every 20 hours as well. I have
not tried it yet, but intend to in the near future.
Ed A
I'm running the stock Mazda ECU still. It runs the engine rich best-power
all the time, automatically compensating for altitude. This is open-loop
mode not using the O2 sensor. It only uses the O2 sensor below 3000 RPM,
which means it's only using it while I'm taxiing or on final approach. In
fact the wire to my O2 sensor is broken, doesn't matter, I'm not using it,
and it has no effect on engine operation even at idle RPM. The ECU will
still run the engine without it.
The problem with 100LL is it fouls the leading spark plugs after about 4
hours. The symptoms are exactly like SAG, just after takeoff with the
corrupted plugs, there is a power loss and the engine is running only on the
trailing plugs. When it first occurs, I can throttle back a little for a
minute or so, then throttle back up and it clears. As the plugs get more
corrupted this will no longer work and the plugs need to be removed and
cleaned.
So on my long trip to Kansas last summer I was able to burn mogas all the
way to Kansas and on the return until I got to Logan Utah. I had some
Decalin TCP with me to try because the fouling problem is well known to me
and I avoid 100LL like the plague. I was west of the Rocky Mountains so I
had many more options to land on the way back to Oregon, so I put in 100LL
and TCP since I had no contacts in the area to help obtain mogas. I didn't
have quite enough fuel to get all the way home to McMinnville OR so I had to
stop in The Dalles to add a few more gallons of 100LL. By this time I had
been burning 100LL for about 4 hours. Sure enough, as soon as I took off
from The Dalles, big power loss. I circled the airport in the pattern
throttled back until it cleared, then climbed out to the west over the
Columbia river, everything fine from there to MMV. But I took the plugs out
and cleaned them before my next flight and tried to dilute the remaing 100LL
in the tanks with as much mogas as possible. At least in my situation the
TCP did nothing.
I've built a circuit to intercept and manipulate the airflow sensor signal
to the ECU, for rich/lean control. It is installed in my RX-7 and works,
eventually I will transplant it to the Long-EZ. Also considering a MSD
system.
Perry
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