John,
I'll try to add some light to the subject.  I have the EC-2 and the EM-2 on my n/a 20B.  I recently relocated the primary injectors back to the stock location on the block.  These are unique (low profile) injectors, and I therefore was forced to go with the stock 550cc ones.  The EC-2 program map starts with all the settings at 0, and allow you to change it to +127 or -127.  In order to get my n/a 20B to idle smoothly, I had to set a/f settings to minus 100.  That would require many, many pushes on the program button.  Also, it depends on how far left/right of 12 O-clock you turn the program knob as to how much effect each push of the program button will have (9 o-clock makes large differences, 11:30 makes small changes).  It runs fine now, and idles down to about 1000 rpms.    

The point here is the extreme settings it took to get it to run right.  Without the EM-2, you have very little idea of where you're at, or which way to go.  The O2 sensor has a lag, and is not a very good indicator to use, per Tracy.  IMHO, If the only thing the EM-2 did was to provide a way to see and map the EC-2, it would be worth the price.  And yes, it does provide a/f readings.

Mark S.

10:30 PM 7/1/2004 -0400, you wrote:

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.