Ok I have been having this rattle for a long time. I never really noticed it until I got the snow tires on because they are 10x quieter than the stock tires.

During light acceleration (pedal 1/3 or less) I get a rattle that sounds like a relay cycling on and off very rapidly. It comes from the driver's side under the hood area. It goes on for about half a second if I press lightly on the gas in any gear while the RPMs are low. It does stop after a half second or so regardless of pedal position.
It also happens when I let off of the gas from light throttle.

I guess it could be any relay, but it is fairly loud so must be large (such as the ECU relay under the hood) or something like the ACD pump.

Is this normal? Does anyone else have this sound? What is it? Is it related to my Flashed ECU (maybe idle speed stepper motor over driving itself)?

 

C'mon people if you bothered to read the post at least you can reply so I know if this is normal or not. Even if your car in no way makes this noise let me know that it is abnormal.

 

I never heard of this bro! are you stock? what are the gauges reading? I will think on this one. I have an 03 though, don't know if it matters, does it? Will get back to this later!

 

Exhaust and flash only.

 

What all mod's do you have done? I had the same exact thing happen to me, but i found out later that my downpipe came loose and it was hitting the cross bar. I thought it was something with with the ecu or something stuck in my engine too, but come to find out it was my downpipe lying on the cross bar. Pis**ed me off. But this may not be the case for you. Just my 2 cents since no one else will help. lol

 

I was going to say the same thing as bdub. I have the RMR exhaust, and the "rubber-foil" pad, glued to the oil pan, came off, and caused the rattle. it seems to be RPM constant, ie the "harmonics" at those gears and RPM's set it off.

 

I thought i was crazy...i heard the same thing yesterday and i thought something was wrong. I heard it all day yesterday and it was very cold out. I haven't heard it today so i just dropped it but since you are hearing the same thing that makes me wonder. And you are right it happens for like a second when you get on the gas and when you let off...i can't figure it out.

 

Yea, i'm actually still trying to figure out what to do to try to make that rattle stop. Any ideas?

 

I have a real annoying rattle too. And like yours, only at certain throttle position/RPM. But its not under the hood. It sounds a little like it is, but its just the release button on the E-brake. Kinda sounds a little like coins rattling in the ashtray. Next time you hear it, reach down and put your finger on the e-brake button and see if it stops.

 

It sounds more like it is on the firewall on the driver side. As i put my head down more between the steering wheel and the door you can hear it better so i don't think it can be the e-brake but i guess it wouldn't hurt to check.

 

Yep it is as DarkEvo describes. I think it's either something to do with the flash (idle stepper motor, boost control valve) or it's the ACD pump.
Or one of those relays in the relay box right there on the driver's side under the hood.
I suppose it could be the downpipe but honestly there is tons of space there and it just doesn't sound like an exhaust rattle, it is kinda plasticy and electronic sounding.

 

Yeah, its pretty easy to reach down and touch the e-brake. I know it sounds dumb, but i'm serious. I've had people in my car, in shotgun and in the back that are like "whats that rattle coming from under the hood?"

 

I have a rattle from what It sounds inside the dash the only way to make it go away is put pressure on my dash where the plastics connect so its obviously something loose.

 

Well I drove the car around just to satisfy those of you who don't believe me when I say it is not something loose and rattling. I held the ebrake, and the noise still comes from under the hood. I poked at the dash and the noise still does not sound like a loose peice of anything rattling. It is defenitely some sort of relay/electrical thing doing something.

 

hmmm i jus got the same problem today... i launched my car and im driving home from werk and the rattling sounds on the driver sounds hopefully sumone will figure it out hope its not sumthin major...