Question : 2.8 Carb Mix Control Solenoid Adj w/DVM Duty Cycle

[83ste]

I have an 83 2.8 HO carb (E2SE) and would like to know if anyone has adjusted the mixture control solenoid with the duty cycle function on a Digital Volt Meter. If so, what is the rpm and duty cycle? The factory method calls for using a self powered dwell meter, which I don't have. A non-self powered dwell meter will load the ECM too much and blow the ECM fuse.

[86FieroSEv6]

I have a Fluke 88 which has dwell function. As for the powered vs. non-powered...I used to use an old Actron dwell/tach meter and never had a problem with overloading the circuit. Alternatively, I believe that there used to be a chart for calculating duty cycle dwell using measured volts. Back in the day, I found my best results were by watching the m/c parameter on the scanner while fine tuning with the exhaust gas analyzer. Another useful tool that is built in to the GM CCC system is called O2 monitor or feedback monitor mode. Once you have the car warmed up and in closed loop, jumper the ALDL terminals as you would for gaining trouble codes..(pin A to pin B). If the vehicle is in open loop, the check engine light will flash at a slow steady rate. If the vehicle is in closed loop, the check engine light will flash much faster. The higher the cross counts, the faster the flash. During this mode, when the light is on, the O2 sensor is above 455mv, when the light is off the O2 sensor is below 450mv. Expected norms are more than ten flashes in ten seconds while holding the throttle steady at about 2000 rpm. If you are getting more than ten flashes in ten seconds you would next note whether the light tends to stay on (rich) or off (lean). A properly adjusted system should have a nearly equal on/off ratio with 12-16 flashes in a ten second period @ 2000rpm warmed up in closed loop. Damn, it's amazing the stuff you remember when you are posting....hope this helped.

[83ste]

You've got a pretty good memory - that O2 monitor is a good function to know. I may have to use it if I can't find some exact numbers, since am looking to fine tune the carb without an analyzer. I seem to recall a 50 % duty cycle at 2000 rpm, but it's pretty rough. If I could find the chart that would be best.

I tried a no-name dwell meter blew the fuse, so you Actron unit must draw less current.