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[rsicard]

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.

[BLG355]

It should constantly switch rich/lean. It should look like a sin wave on a graph.

BLG

[brian617]

Switching is normal, this is a product of the o2 sensor and Intergrater/BLM activity in closed loop. Have you determined whether or not your'e in closed loop? If in closed loop what are you BLM values at idle with normal coolant temperature?

Maybe the first thing to do is find out why the check engine light is on? What DTC code?

Depending on what ADX file you are using and what initial advance is set in the .BIN will cause the timing on TP5 and timing light to not agree.

I still don't see any reason to run the export .BIN, it's likely to be an open loop calibration. I looked over that .BIN again the other day and didn't find any real proof that it's made for Vortec headed trucks. Also as Fast mentioned it's a $63 mask which there is no XDF for tuning.