I've had enough of the fog horn sound coming from the intake!!!! Help!!!!!!
 

Has anyone experianced this? I posted and searched about it about a year ago, with poor results. On cold morning start ups my truck gets a nasty reverberation sound in the intake that sounds like a fog horn. I thought it was my AFTB but after making several adjustments, I realized that is not it.


HELP ME!!!!!!!!!!!!!!!

Whip- I also had that exact "moan" on cold mornings at idle or even at a light slightly after warm-up.I mentioned how it drove me crazy once to Ron at Metco after meeting him at one of the car shows.He told me a friend of his friend had the same problem and that it was remedied when he added a breather cap to the passanger side valve cover. Now I already have a breather on my driver side, so just for kicks I added one to my pass side and guess what? No more foghorn!! He explained to me that when I added bigger pullies that the engine was pulling the needed air from the air intake rubber boot causing a "singing" that was more apparent when the air got colder. Now I can't say if it was in fact that, but I haven't heard it since. Its worth a try. Hope this helps. - Armand

Thanks man....worth a try I guess...

I get it occasionally and have had a breather cap on for at least 10,000 miles. Truck has 18,000 on it now and it only happens after cold startups

Yea, but did you have breathers on both sides? I had only one on the drivers side, but it wasn't enough.Once i put on the pass side breather it dissapeared.

breather caps make such a mess though...

When I installed my cervnis hood on my truck it would whistle at 42-47 mph. It was a very annoying sound, i ended up taking the aluminum inserts out and the sound was gone i know this isnt your problem but I have always wondered if anyone elses does this.

I have a similar "whistling" or howling sound on cold mornings. However, my truck is stock.

Any ideas?
I was thinking it may be the smog pump acting up.

Paul G.

Wow!! This is the first post about this that I have seen. I have the exact same annoying sound on cold/cool startups. It really sux. I too would like to know how to stop this but am kinda weary about having two breather caps on since one made a nice mess by itself.

Later
Damon

Will two breathers affect the af ratio? If I'm not mistaken, the chip takes into account for one breather, since you are introducing unmetered air into the system....

Mine sometimes does it when its cold and always does it when its really hot out (85+)...

I never figured out what it was...I just kinda ignore it these days.

It did it when my engine was stock, I changed my upper intake and tb and it still does it...so no clue.

only moans at around 1000-1200ish RPMs.

Dan

You're probably experincing what most Ford techs refer to as "moosing" or "hooting". Basically, the Idle Air Control (IAC) valve is going bad, and causes rough idles and that annoying sound on colder days. The sound should wear of once the engine is warmed up enough. There are ways to "cheat" the IAC for awhile, but basically you'll need a new one soon.

Interesting data.That sounds like it may be a possibility.Where did you hear of this?

Interesting..I'll check this... I don't have any idling problems, I just occasionlly howl...though it is repeatable when its hot.

.I've been having the same problem for a while on and off on my 02L. Only on cool/cold mornings but will go away after a minute or so. New IAC valve will eliminate this? Definitely worth checking in to.