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Rotarians,
I'm
still trying to program my EC2. Here's what I did tonight:
I
checked the EGO sensor by heating it with a blow torch. Voltage varied between
0.9 when hot to 0 when flame removed. (See the "how to check an EGO sensor" text
below - does this sound right?).
I
started the engine on the ramp (at night so I could see the air/fuel (AF) gauge
).
The
engine started fine on full rich with cold start on. I turned off the cold
start, brought the rpm up to 2500 and leaned to the center. Engine ran ok. Turn
toward rich and it falters, turn toward lean and it runs better. At full lean it
runs best. AF reading is in the center. If I move toward rich the
reading goes higher and engine falters past center.
Turn
to mode 3, move program knob to left and press store button. No effect. Press
again 6 times. Still no effect either on the engine or the AF reading. Turn to
mode 1. Move mixture to left. Move program knob to left. Press button. No
effect. Press button 4 times. Still no effect on AF reading or engine. I turned
on the cold start switch. No effect on the engine or the AF reading.
After
this I taxied up and down a bit at various rpm settings until the temps got too
high. The AF reading stayed pretty much in the center at all times. Maybe one
yellow bar on occasions. The engine runs quite well at all rpm, and there
wasn't much, if any, soot on the prop when I ran it with the mixture on full
lean.
I get
the impression that the program button isn't doing anything - but the B computer
has a copy of Tracy's original settings (I think) and the engine runs worse when
I switch to it, so I must have changed something on A. A while back I
checked that there's a ground on the proper pin when the program button is
pressed, and I checked continuity on all the wires from the control panel pins
to the EC2 pins. I guess I'll check all this again tomorrow.
Those
who've programmed an EC2 using the AF gauge - do you see an obvious effect when
you store a change? How many times do you have to press the button to get a
visible impact?
I know
we've been through all this before. I don't seem to be getting
anywhere.
Any thoughts or suggestions
welcome.
John
Slade (banging my head against the wall)
PS -
Does the EM2 give an air fuel reading? I hope so.
How to check an EGO
sensor.
Use a high impedence DC voltmeter as above.
Clamp the sensor in
a vice, or use a plier or vice-grip to hold it. Clamp
your
negative voltmeter lead to the case, and the positive to the
output
wire. Use a propane torch set to high and the inner blue
flame tip to heat
the fluted or perforated area of the sensor.
You should see a DC voltage of
at least 0.6 within 20 seconds.
If not, most likely cause is open circuit
internally or lead
fouling. If OK so far, remove from flame. You should see
a
drop to under 0.1 volt within 4 seconds. If not likely silicone
fouled.
If still OK, heat for two full minutes and watch for
drops in voltage.
Sometimes, the internal connections will open
up under heat. This is the same
a loose wire and is a failure.
If the sensor is OK at this point, and will
switch from high to
low quickly as you move the flame, the sensor is good.
Bear in
mind that good or bad is relative, with port fuel
injection
needing faster information than carbureted systems.
ANY O2
sensor that will generate 0.9 volts or more when heated,
show 0.1 volts or
less within one second of flame removal, AND
pass the two minute heat test is
good regardless of age. When
replacing a sensor, don't miss the opportunity
to use the test
above on the replacement. This will calibrate your
evaluation
skills and save you money in the future. There is almost
always
*no* benefit in replacing an oxygen sensor that will pass the
test
in the first line of this
paragraph.
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