LSX454 swapped 95 BASS burb.

[r3dd0g]

What about moist air could keep this from idling?

When I held it at 2-3% throttle, it would run. But letting off it died.
I would have thought the cool moist air would be too much oxygen if anything.
But it acted like not enough.

Maybe it was a coincidence and the IAC solenoid was stuck..
But I tried it multiple times.
Then today it starts right up and idles.

Thinking back, it's done this once before, and I think it was raining then too.

Did you happen to see if the IAC was at max open already? If it needed more air and the IAC was already fully opened, that could be the issue. With the truck warmed up and idling it should be at around 5% so it has sufficient range to maintain idle when it's cold.

 

[Babaganoosh]

How big is your throttle body? When adjusting the iac I like to start the ramp around phoenix lowest temp and work my way up and also don't forget to do a TPS relearn as well.

 

[shady]

It's a 102.

It did it again today outside with a bunch of dew/fog.
But after a little bit of holding it at 2-3% I let it go slowly, IAC went up to 86, and it sat and idled.

Had the IAC set to idle at about 8%. Which is an average because it bounces all over so it's hard to know what it really is. Idles too erratic for it to just set at a number.

 

[folkenheath]

Will it not start or it just won't idle unless you keep it running?

Sometimes these things point you in two different directions and you just have to try both and see what it wants.

If the engine is cold it might want less timing at cranking or idle to give it more time to compress the charge and create heat before the spark.