Thanks Ed. I got no reading on the ground taxiing, I first noticed a
reading as I was climbing out.
A very consistent 0.8 average throughout the flight. The ECU is not
actually using the O2 sensor
during any RPM setting I use for flight. It only goes closed loop below
3000 RPM or thereabouts.
I'm only at that power setting for base and final.
I can believe it is operating on the rich side, as I think my fuel
consumption is rather high, 7 to 8
gph operating at 5200 RPM. My fuel burn rate is higher than the O-235
LEZ I flew backseat
to Mojave, but of course that is a piston engine.
By having a free flowing exhaust system as compared to the car, would
that lead to richer
operation? If there is some logic behind exhaust system changes
affecting mixture maybe someone
can explain it to me. Less back-pressure of course, but I can't
immediately see how that would
affect mixture.
So I guess the white color of my exhaust ports does not indicate lean
operation.
All sensors used by the ECU should be operating correctly. The ECU puts
out a code if any of the
required sensors are not operating correctly, and I have 2 LEDs on my
instrument panel to
monitor this output.
The next step is to put a fake water temperature signal into the ECU to
see if I can affect mixture.
--
Perry Mick
Perry,
7 GPH 42 PPH .5 bsfc = 85 HP
7 GPH 42 PPH .6 bsfc = 70 HP
8 GPH 48 PPH .5 bsfc = 96 HP
8 GPH 48 PPH .6 bsfc = 80 HP
That is not a lot of HP out of your stock engine at 5200 RPM.
if the peak HP is around 6000 and is about 160 HP that
should be around 140 HP or so. See the stock dyno chart
below.
My engine is rated 146 HP @ 6500, so 5200 would be about 117 HP
The color of your exhaust and these numbers are a strong
indication you are running lean. Is the O2 sensor fresh
or has some 100 LL been run through it lately?
No, old oxy sensor. I don't burn 100LL anymore, haven't for almost a year.
I'm thinking it is running rich, and that is why the 100LL fouls my
plugs so badly.
I could buy a new oxy sensor and see if it's any different.
What was the cruising speed of the O-235 Long EZ?
70% power on the 115 HP O-235 is 80 HP. At .45 bsfc that is
36 pounds per hour or 6 GPH. At an unlikely low .4 bsfc that
is 5.3 GPH.
I think we were doing around 170 mph. It just seemed like his plane was
sipping gas
compared to mine. Maybe 6 gph.
Are you simulating any sensor inputs to the CPU?
Have you measured the intake manifold pressure?
Perhaps your tach is off.
Paul Lamar
I am not nor ever simulated any inputs to the ECU, but may try water
temp soon.
I have an intake manifold pressure gauge in my cockpit. My tachometer is
digital
and counts ignition pulses, it is not inaccurate. I don't use that big
one from the car
to fly with because it's not in front of me when I fly.
What do you think about exhaust system having an effect? Less back pressure?
Would it tend toward lean or rich by removing the cat converter and muffler?
--
Perry Mick
--------------------------------------------------------------------------------
Its hard to say as I don't know what strategy the CPU uses to adjust the mixture.
The mass airflow sensor could be sending the wrong signal.
Checking the manual I see the mass airflow sensor is the trap door type.
Yes it is the flap type.
According to 79-85 shop manual there is a choke switch and a throttle
position sensor input to the CPU. I am sure the throttle position sensor
could be tricked into thinking the engine had more air than it really did
as it is just a pot.
Throttle position sensor is only used down near idle. No choke switch
I'm aware of.
There is a water temp. switch. Cold or warm.
There is an atmospheric pressure sensor. I also see an intake air temp sensor.
There is a water temp switch - I think that is used just for starting, I
have it faked out.
There is a water temp sensor on the back of the water pump that does go
to the ECU.
These are the only sensors / inputs to the ECU required to run the engine:
ECU
Code Failure
01 Crank angle sensor - no failsafe mode
02 Air flow meter.
03 Water temperature sensor.
04 Intake air temperature sensor - airflow meter.
05 Oxygen (O2) sensor.
06 Throttle sensor.
07 Manifold Pressure sensor.
09 Atmospheric Pressure sensor.
12 Trailing side coil failure.
15 Intake air temperature sensor - intake manifold.
I don't simulate any of the above inputs, but I do simulate some of the
switch inputs, as
shown in the attached GIF.
What year is that CPU and engine?
1986
What manifold pressure are you seeing?
I was flying between 0 and 4500 feet. WOT is 5500 RPM but I usually
cruise 5200 RPM. Didn't
notice the manifold pressure but I could take a note of it next time.
Very very important. Power is directly proportional to manifold pressure.
I think you are being pessimistic about the HP. I know you are running the
dynamic chamber EFI system and according to the dyno curve it is 160 HP
at 6000... 6500 RPM and 140 HP at 5000. I think the lower HP 13B engines used
the 4 barrel carbs such as my 76 Cosmo and my 75 RX4 station wagon.
Is your engine a six port?
If you look at the dotted line in this curve the 140 HP engine is making
125 HP or so at 5000 RPM.
Having seen your exhaust I am willing to bet your engine is too lean.
Paul Lamar
What if it was just running lean down near 2000 RPM while I'm taxiing
back to the hangar?
I don't know if that would be long enough to get the white color though.
--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com
I don't think so.
Paul Lamar
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