Originally Posted by
rsicard
Appears the next course of action would be to disconnect the IAC valve to see if that stops the cyclic behavior with lean/rich injector pulse width and o2 on this 350 Vortec with 454 throttle body. Trying to achieve the objective of getting a good idle RPM and lean injector pulse. Maybe retarding the ignition timing will bring down the idle RPM. Yet the ignition timing seen on TunerPro and the actual with a timing light do not agree. Need to establish some kind of relationship between the two. Will disconnect the ESC and the IAC valve, set the distributor timing with the timing light, see what the PCM is commanding via TunerPro, then reconnect ESC with the engine running and see what happens with the timing light.
Need comments from the experts concerning this cyclic behavior. Maybe it is just an incompatibility of the binary with this particular engine?
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