Hey guys been having this problem for a while but all of a sudden the noise was getting louder and louder to the point that if i'm at a stop light I can hear it. It sound like a backfire something like a blupp blupp blupp I have no trouble code and the cars running like its old crappy self but I'm just concern it may be trouble lurking down the corner and if I prevent it might as well take care of it now. Oh yeah and it only happens while idling. Thanks

car info:
03 expy, 4.6l, 120, xxx miles, k&n sys

 

You sure it's coming from the intake? The only noise that I can think of is one that the PCV valve makes when partially plugged. If you have a scanner, scan it anyway, -you may have something pending. Without a DTC it's hard to say. If she's running bad @ idle, I would check the EGR valve.

Make sure your engine light is working. Turn your key to run, it should illuminate regardless.

Are you up to date on your fuel filter ? The fuel system would be the next to check out. Check pressures. Also, makes sure the MAF is clean.

 

See if this sounds like your issue??https://www.f150online.com/forums/su...ing-noise.html

 

Yea, that's called the IAC horn and it's a 4six thing. The 5four is different, -horns in the back and it's round. That one slipped my mind , but that's correct , IF the engine is running correctly. You need to integrate that black box back into the line.

 

I did most of the maintenance less than 500 miles ago I don't move the truck as much anymore so I'm sure it ain't any of that or I hope it ain't. The only code it throws is a p1000 but thats probably cause I had a vacuum leak and I haven't ran the truck more than 5 miles after that.
It ain't a howling noise its more like when you submerge something under water like a bottle and the air bubbles are escaping. I'ma see if I can find a way to record the sound. If its eating up antifreeze will that be a problem. . .THANKS GUYS

 

p1000 means you reflashed the computer reset and there is no info in the emissions computer, it will go away after a few weeks of driving.

 

Just throwin' this out there for comments....

This:

Plus This:

Equals trouble, imho ...

I do not believe in coincidences. Have you checked yer oil for water, and/or checked yer overflow tank fer oil?

Good luck.

MGD

 

Nope no water in the oil or oil in the antifreeze . . . I asked a mechanic friend and he says it maybe a head gasket (due to the fact that I told him about the antifreeze which he says may be going out the tailpipe) so i took out the oil last night and since there was no water into it i threw it back in this morning. But theres no white or blue smoke so thats why I hope its not the gasket . . . THANKS