sometimes when im accelerating from 1st or 2nd gear (usually 2nd), i hear a knocking noise for a second or two. anyone know what im referring to? had this problem before?

i have a 2003 g35 6mt coupe

 

What year, what tranny.. come on... give us a LITTLE info please

 

my bad... lemme update the info in the first post.

 

noise from the front or the rear or the transmission if you can tell?

check the undercarriage? any aftermarket parts beyond the z tube and k&n?

 

it sounds like the noise is coming from the front. only got a ztube and k&n.

 

see if the everything is bolted properly, may just be a rattle.

 

there was a knocking noise i used to get from the rear when I upgraded my sway bars. apparently the end links were not strong enough and my dealer replaced them under warranty (even though I had aftermarket sways).

i would check with the dealer if the issue persists - could be an endlink or sway bar issue...

 

i know for sure it isnt the ztube or the k&n. even if it were loose, it wouldnt make a clunk noise like that. it may be the suspension or engine/tranny related.

 

hmmmm...

this usually only occurs during the 2nd gear when i mash on the gas. it sounds like woody woodpecker is rapidly peckin on some hard wood or something. no one has experienced this?

 

Yep, I get it too. I have an '04 Coupe 6mt and get the same thing...I hear it best in second gear upon acceleration. I've taken it to the dealer and had them check it out and they say it's normal. I run nothing but 93 octane. I live in Texas and the problem occurs very frequently during the hot summers we get here. However, in the winter, it's not a problem. Some have suggested getting a cooling system flush. I am planning to do that in addition to probably a 40/60 mix of Amsoil Antifreeze/Water. For good measure, I've got a bottle of Red Line's water wetter that I'm going to use as well. Our engines are somewhat higher compression at 10.6:1 than your average Accord that runs fine on pump 87. I'm suspecting that if I can get heat transfer out of the heads slightly more efficiently that I may be able to cure the issue. My pinging is only slight yet it's something I don't feel should be happening on a $35k+ car.

 

is yours more of a pinging or mild knock sound? either way, it CANT be normal. ya know? how would a colling system flush take care of that problem? i think i'll take mine to the dealer too.

 

The dealer says mild pinging (which is what I have) sounds like ball bearings rattling around briefly. The knock sensor detects it, retards the ignition timing and it goes away. The pinging sound is caused by detonation or pre-ignition in the engine and is the byproduct of fuel in the combustion chamber beginning to ignite before the fuel is ignited by the spark plug. In essence, you get multiple flame fronts colliding into each other inside the cylinder and this is what is causing the pinging or knock sound. Hot spots on the cylinder head can exacerbate the problem. Flush your cooling system and you'll have a better chance of getting good thermal transfer from the head to the coolant. Also, having a higher water to anti-freeze coefficient will increase the ability of the fluid to transfer heat. The drawback is that it slightly lowers your boil temperature. Normally most people run a 50/50 mix of anti-freeze to water. However, running a 40/60 mix will not have a significant impact on the boil temperature of the coolant.

Hope that helps.

 

yeah... but the thing is, it doesnt sound like pinging? its more like a mild knocking sound. hmm... that still cant be NORMAL like the dealer say.. ya know what i mean? plus, it only happens during 2nd gear, which is kinda strange if there were any detonation goin on. i would expect it to happen at WOT on more gears.

 

have you checked your oil level?

 

if the dealer says its normal, have them take you out in one of their cars that do make the noise also... betcha they can't find one.