Hearing weird sound under the hood!

[bigj884]

im not to sure what this could be so figured maybe you guys and gals could help me out....

i have an 02 Auto p5....just for refrence

ok here is the problem.....recently i have been noticing a sound coming from under the hood....it sounds like something is rattling inside the engine when i am accelerating hard....anytime i just floor it i hear it it sounds like beans or something in side a can.....

but i never hear it at an idel nor do i hear it when i just drive normal....and when i do hear the sound under hard acceleration i only hear it as the tranny shifts through 1st and 2nd....after it reaches 3rd gear i dont hear it any more

anyone have any clue what this could be....

i also still have warranty on the car...and i thought about taking it into the dealer but im not sure if the would honor my warranty since i have modded the car....although the only engine/performance mods i really have are a CAI and exhaust.....no cams or anything like that

any suggestions and comments are greatly appreciated

thanks

 

[Jack Daniels]

My initial thoughts are intake butterfly screws.

 

[bigj884]

so if it is that....how do i fix the problem??

 

[aMaff]

My initial thoughts are intake butterfly screws.

maybe, but he said not at idle. Does it sound like it's coming from under the hood? Take a look under your car, when I did my exhaust, I had a noise that sounded like it was coming from directly under me, so I thought it was hitting the heatshield. I hadn't let the loc tite sit long enough, and 2 nuts at the BACK (axleback) section had worked their way loose. Didn't make any noise at idle, but when you accelerated, it would rattle like hell. Just a thought...

 

[bigj884]

no its not the exhaust at all its def coming from under the hood...

and no there is no noise at idle...and i even put the car in neutral and reved the engine and there was no knock or any weird noise....only when i am driving and accelerating hard....and even then it usually stops around 3rd gear

 

[aMaff]

no its not the exhaust at all its def coming from under the hood...

and no there is no noise at idle...and i even put the car in neutral and reved the engine and there was no knock or any weird noise....only when i am driving and accelerating hard....and even then it usually stops around 3rd gear

it's not under load when you rev it at idle. If it was the butterfly valve screws it would rattle ALWAYS (or until the screws got spit out the exhaust port...). Also, ppl (at least, me) don't generally rev 4th and 5th as hard as 1st - 3rd, cuz by that time you're usually just cruising along. It may be a good idea to check to make sure that everything's tight...I said exhaust cuz that sounds like the exact thing I heard, but, whatev. Any1 else?

 

[bigj884]

im not talking about reving hard....i dont have 5th gear i have an auto...and im talking about when i am accelerating hard (flooring it) it does it all the way until the tranny is usually in 3rd gear.....so i hear noise when tranny shifts 1st and 2nd but noise seems to go away when the car shifts into 3rd gear...cuzz i dont hear it in 3rd or when it shifts into 4th....

 

[bigj884]

bump

 

[Moonman8]

sounds like pinging to me. I had this problem a while back and I thought it was the VTCS screws in the intake manifold. Same sound, like marbles in a can being shaken really fast. Also like you, I couldn't hear it just by revving the engine sitting still or under any level of the throttle other than wide open. Pinging is where the fuel inside the combustion chamber is not completely burned in a single cycle and the heat from compression of the piston is hot enough to ignite the excess fuel (rather than the spark plug igniting it). Basically there is combustion in the cylinder when there shouldn't be.

I fixed it by running a higher octane...I was using regular and switched to mid-grade, no more problem. Some also say that a colder spark plug can help but I've also been told the pinging is caused by a wrong octane rating being used for a given compression ratio (the 2.0L FS-DE has a 9.1:1 compression ratio).

 

[bazooka joe]

ya, the ole "rattle in the can nosie" under hard acceleration...ping

 

[nate0123]

have you filled up the gas tank since it started happening? sounds like bad gas to me

 

[Moonman8]

have you filled up the gas tank since it started happening? sounds like bad gas to me

could very well be the case if it has only been occurring during your current tank-full. in my case, I heard the noise over a few tanks so I ruled out the bad gas and upped the octane.

 

[c0nfus3d]

wow i was just about to post about this. im waiting till i hit near empty then imma run higher octane full tank to clear it up a bit see if that helps. for awhile i thought it was the butterfly screws. hopefully just bad gas . after all im hispanic DAMN BEANS!

 

[YodaHo110]

i have tat same exact problem too it makes that wierd sound i guess i gotta try that higher gas....

 

[Jack Daniels]

ya, the ole "rattle in the can nosie" under hard acceleration...ping

Yeah, you're probably right. I guess I wasn't thinking about the obvious.

 

[bigj884]

cool ill try uping the octane.....see if that works

but out of curiousity if i have been running 87 the whole time i have had the car and now this happens......why all the sudden does this happen???

 

[nate0123]

bad tank of gas?

and if that's the case, you wouldn't need to up the octane, just fill up on 87 again and hope it's good gas (or put a few gallons in to see if it goes away, and if not, top it off with 91/93)

 

[c0nfus3d]

well it wasn't the gas, i ran the car a little harder than usual today. drove through the back roads of manasshole this morning for a little fun cruise. but im still getting the "bean in a can" type noise. ill take a look under the car in a couple days once i actually pop my lip or lower her. whichever i have time to do first.