350 Vortec with 454 throttle body on run-in stand
Need help.
When running, this going from rich to lean condition is very much cyclic. Just keeps going back and forth, rich then lean and repeat, repeat. Perhaps IAC is opening and closing at this cyclic rate. Need to modify constants to cancel the service engine soon (SES) light. The same action with the IAC to stop its operation as a trial. Have to monitor IAC commands also. Once the idle has been stabilized, try to retard the idle ignition timing in the PCM to get the idle RPM down to where it should be with a narrower injector pulse width for leaner idle.
Still learning how to tune the PCM. May just switch over to a more compatible export binary set up for the 350 Vortec and TBI. Then tune from that point on.
What are the best ways to tackle these.
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