setting CIS mixture to 3% using dwell meter?
 

Do any of you CIS experts know what the dwell meter reading would be setting the CO to 3% using the frequency valve/dwell meter method ? 81'SC

Hello, no one is willing to step up, so I might as well mutter a few things.
Using the dwell meter method will give you a basic setting, setting the freq valve to where it is operating 50% of the time is ball park.

If you set it to 50% and you hit 3% you lucked out, to fine tune the adjustment you need a co% tester, do a search and you will find several models.

consult your shop manual for %, wether or not you have to disconnect o2 sensor and if you take your reading before or after the catalytic converter.

Hope this helps, I had to set my 80 sc from scratch, I used the dwell meter to get me close, then I bought a Gunsen gas tester and set her right on, good luck,

one last note, don't believe everything you read, my shop manuel said to set my car to .8% well it wouldn't even run, I was told here in this forum, 3.5% , still to lean, 5.5 to 7.5 % my car runs strong, fuel economy is not bad and no back fireing, hunting, surging.

Peter

On a dwell meter (as opposed to a duty cycle meter), factory setting should bounce back and forth between about 40 degrees and 50 degrees, averaging 45. 45 on a dwell meter equals 50 on a duty cycle meter. Use the 4-cylinder setting on the dwell meter.

A richer setting will result in a lower duty cycle. Perhaps 3% is around 30-35 degrees, dwell. That's just a WAG.

WOW, 5.5-7.5% ?? Thats alot..... .8% is fine, but most run great around 1-1.5%. Turbo cars should be set @ 3-3.5%.

How and where do you connect the dwell meter ?

Hello, on my 80 sc there is a test connection, (three wires w a black cap covering three pins)

wire colors are: red= 12 volts
brown=ground
green w/white stripe= pin 15 of my ECU

hook negative of dwell meter to ground and positive to the green w/white stripe.

if you do not have this test connection you will have to take the connector off the ecu and boot and trace to find pin 15 and tap into it some where betwen the ecu and the freq valve, good luck.

Peter