Well today it dropped to about 75 degrees, and I noticed my truck is making almost like a small stick in a fan noise. Its goes along with the engine so it could be a small pinging noise. Even after driving it for about 30 mins or so it was still making the same noise as when I started it. I went to lunch and it warmed up to about 85 degrees and the "pinging" went away.

I just replaced my plenum, timing, 02 sensors, oil, seafoamed it, and changed the water pump.

Thanks for any suggestions

 

Normal. Massive temp changes change the air density and throw the previously stored MAP sensor values out of whack until the truck gets up to normal operating temperature. Even then, cold air and a colder charge is still harder to ignite.

Clean the throttle body, spray some Mopar Combustion Chamber Cleaner through the throttle body while it's idling, and drive it like you stole it.

 

That seems counterintuitive to me. With more molecules of air/fuel mix per unit of volume, there's more go-bangy stuff up against the spark. Idner?

 

Yep. Trouble is, colder air won't hold the atomized fuel in suspension as well, so it tends to 'droplet up'. Liquid gas simply doesn't burn. Vapors burn.

 

Dammit, twice now i have tried to write an explanation and have been told i have timed out. I've about had it with this damn forum.

HeyYou's explanation is correct. That's what happens on a cold start up.

That is why you shouldn't polish intake runners. The smooth surface will promote the fuel staying together instead of atomizing the fuel. The rough surface is actually a benefit in the intake runner. After the intake valve heats up it might be a moot point, but cold startup and idle would be a real bitch with polished runners.

Carbon build up on intake valves also contributes to poor running as it soaks up fuel and releases it as drops. The carbon doesn't get hot like the steel valves and soaks up fuel and releases it in drops, which is why you always see more carbon build up on the bottom half of the backs of the intake valves.

 

At the OP's biting cold 75F?

 

Wish it would "drop" up to 75 degrees here! I bet that was a typo and the temp dropped 75 degrees......

 

I'm hip! We aren't seeing 75F until June at the earliest. A friend of mine in north Florida says she's seen 50's so I'm figuring the OP is Space Coast or south of there. I could be wrong...

Right around here, 40F drops are pretty common (pretty much every day things) and going 40F to -20F isn't unheard of. I just don't know of anywhere where 75 degree swings are to be expected so I took OP at his word.

 

I misread it as a 75* change, so perhaps it is something else. I'd be leery of chasing minor gremlins on a 10+ year old motor.

 

yep south Florida isn't the coldest area
But I know I shouldn't be searching for such a small problem but my truck was running so good