Not sure whre to post this so I'll try here first. For the last week or so there is a strange hiss or rattle coming from the truck when I get up to 38 mph and I'm on the throttle, when I back off, the noise stops. When I get back on it noise will come back but when I get to 42 or 43 mph noise will go away while still on the gas. When I get to around 58 to 61 mph noise comes back and will eventually goes away when I get to 70 mph. Now, this only occurs when I'm on the throttle and it does not happen all the time, though it does happen EVERY time I drive the truck, and every time I back off the gas, it stops. Also, when I go under an overpass it echos loudly like it is an external problem on the truck. Now I have to giye a little background info, which will explain why I posted this in the engine thread. I had been running a K&N intake for about 15 months, when I decided to put a Volant intake on it instead. Did this 3 weeks ago. Around a week and a 1/2 ago this noise I'm getting starts. Well took off the Volant and went back to stock thinking I have a lean condition with engine. Noise is still there! Been running stock for 4 days now. Took truck to a dealership to get a cluster programmed and decided to tell the mech. my issues as far as the noise is concerned and he did a complete computer diagnostic on it and nothing came up. Oh yeah, whole time this has been happening, no engine codes or anything like that has come up. I've checked the plugs and they check out ok. Getting ready to fill the tank with premium for the first time ever just to see what happens, though the tech pretty much ruled a out a lean condition. Anyone else ever have a problem like this? I really don't think it has anything to do w/ the CAI. Any information would be appreciated as this thing is driving me f#%$!* nuts. Thanks. Almost forgot, it's a 2005 f150 w/ a 5.4l

 

I would say it was the CAI being pushed too far on to the TB where it partially blocks the PCV inlets but if it still does it with the stock intake I guess not. It could be a vacuum leak in the PCV system or possibly an exhaust leak since you can hear it echo in a tunnel.

 

You sure it's a hiss and not a high freq. rattle? Ford has had a big problem with cat shields for many years and when they first start out, its such a high freq. rattle, I think it might be mistaken for a hiss. Seems to match up to some of your description.

 

No I'm not sure. It does sound more like a rattle but it only happens when I'm on the throttle and I have to get up to around 35 mph before it will start to rattle (or hiss) and it will stop as soon as I let off of it. That's why I was thinking maybe a throttle problem. Btw, I've already checked the exhaust and cat sheilds and found nothing wrong or loose. I also filled up with 93 octain today, burned up a 1/4 tank and still no change. I'm going nuts with this thing.

 

My cat shield isn't loose as far as my hand can tell, but its definitely where my sound is on my 2000. It seems to have to be something in the exhaust since you can tell the difference in an overpass.

 

I'm hoping I've narrowed it down to 2 factory couplings just past the quad catalytic system they have on the 5.4s. Tapped at one joint and it didn't sound all that solid, though it didn't really seem to be that bad. To be on the safe side though will probably remove the factory couplings and weld on 2 of my own. I know the reason for the couplings, but I've decided to cut out the 2 cats PAST the O2 sensors and run a true dual exhaust. I know we're talking about exhaust in an engine thread and I'm still a little worried I might be grasping at straws here and actually have an engine issue. I sure hope not . Will keep posting on situation.

 

Could it be an exhaust leak from the manifolds. They have known to warp. And the sound comes and goes depending what speed (or RPM) you are at and if you are in the gas. Sounds like a possibility.

 

I have a 2003 SD with v10 and 6speed stick 25000 miles--I have a rattle for two years and now getting worse. Dealer found tech bulletin on heat shields-mine were tight but they changed the front pipes anyway. Noise is the same.They tried to say it was the clutch. I know of 2 other sd's with automatics and they have the same rattle. There is no way its an exhaust leak,sounds like a tin can rattling only when on the gas. Nxt step is to remove cat and see if noise goes away.Has anyone tried this?

 

Just got off the phone with banks exaust.I also have a rattle that started about a few thousand miles after i instauled there exaust.Only stock part left is the cat and it seems to be tight.It makes the noise only at low speed when i give it a little gas(only in high gear).I get no noise when towing my 10000 lb trailer.My truck is an f250 v10.Going to my buddy at the trans shop to see if its in the trans.At this point i hope it is so i can get it fixed

 

I have a 5.4 liter engine with 50,000 miles and the same rattle noise just started, it was much louder initially too. I took it to dealership twice and they claim they checked everyithing they said they do not know what it is, they need a factory engineer to come out and help them. I am waiting on that now.
I have custome air intake and exhaust but nothing changed for last 45,000 miles.

Has nayone else taken their rattle noice to dealer?

 

I get this same noise on my (new to me) 2003 quigley e250 5.4. it is a very tinny\grinding type noise only under light accelleration. I'm going to try and put some heavy dutty hose clamps around the cat shield. Has anyone found a real fix?