Engine Rattle?

[Daishi]

Hey guys what im experiencing is kind of tough to describe so bear with me. Under high loads right around 2700-2800 rpm you can hear what sounds be be a grumbling rattling noise. My current mods are Injen Intakes, Fi headers and FI catback exhaust. The noise cannot be heard under any other rpm range. Ive looked around and cannot find anything hitting anything that may cause any type of unwanted noise. The intakes are secured properly and so is the exhaust.

At this same rpm under high load there is also a somewhat dead spot in the power band, Is it possible its related to the noise? possibly.. but I hear that you get that slight dead spot due to installing aftermarket intakes. My car is currently cobb tuned and ive tried a couple different tunes from different companies and it has yet to rectify the dead spot.

Is anyone else experiencing this grumbling rattling type noise at that rpm under high loads with an Injen intake? The only thing I can think of that it is is the vvel system making some noise which is more audible due to the intakes because I remember hearing a somewhat similar noise when my civic si vtec kicked in. Thanks for any help.

btw: I only use 93 octane fuel

[6spd]

is your shifter making noise?

[1slow370]

the vvel gets blamed for so much it's sad, i had a grumbly rumbly noise once but that was my crank walking so if you can get your crank pulley to move back in forth your screwed. also vtec is nothing like vvel there is no kick in point it just does it's thing quite smoothly all the time at every rpm. i would say if you are dissatisfied take it to a dealer(will probably throw a fit from your headers) or bring it in for a dyno/investigate your noise as they should be able to hold it there and see whats goin on with it, or at least around where the noise is coming from.

[Daishi]

My shifter isnt making noise it's definitely in the engine bay. I don't have an aftermarket crank pulley or anything. How would I test out my crank pulley. Can I do that myself? My dealer probably won't want to help me due to the mods. I dont think its crank walk because normally you would hear it while your idling and revving the motor. You can only hear my problem while driving at a particular rpm

[1slow370]

no i mean my crank was walking, there was nothing wrong with the pulley the thrust bearing was gone out of the engine and since the crank pulley is attached to the crank you could move the whole crank shaft back and forth by pushing/pulling on the crank pulley. If the car just sounds different with no accompanying vibrations to co with it chances are your bearings are fine, it might just be a resonant frequency in your exhaust at that rpm.

[elmz]

Hmm...I have a rattle too but mine isn't coming from the engine bay. Mine is inside the muffler, and I doubt the dealer will cover it under warranty with HFC's installed. I didn't want to get a CBE but I guess I have too now.

Good luck on your rattle issue.

[Daishi]

Originally Posted by 1slow370

no i mean my crank was walking, there was nothing wrong with the pulley the thrust bearing was gone out of the engine and since the crank pulley is attached to the crank you could move the whole crank shaft back and forth by pushing/pulling on the crank pulley. If the car just sounds different with no accompanying vibrations to co with it chances are your bearings are fine, it might just be a resonant frequency in your exhaust at that rpm.

It's possible it's a resonance frequency because of the long tube headers but who knows. I'll try seeing if there's any play in the crank pulley but you would hear it at idle while revving If there were.

[1slow370]

my money is on resonance the aftermarket exhausts are stiffer and not dampened as well as the factory ones so they tend to make these funny resonances sometimes. A lot of times it helps to just loosen them up and tighten them back down to let the pipes move and do their thing from the heat stresses.

[Daishi]

Originally Posted by 1slow370

my money is on resonance the aftermarket exhausts are stiffer and not dampened as well as the factory ones so they tend to make these funny resonances sometimes. A lot of times it helps to just loosen them up and tighten them back down to let the pipes move and do their thing from the heat stresses.

Sounds good. Ill leave it the way it is and if it starts getting loud or anything Ill keep you guys posted on what happens. Right now its something thats only really noticeable to the driver who daily drives the car. Its not very loud and you have to listen for it and know when its coming.

[mantella87]

Doubt the OP will reply, but I am experiencing the exact same thing after installing the Injen CAI. I've read a couple times on here that it is most likely an A/C line hitting an intake tube during that RPM range. Like I said, this is exact thing is happening to me.

[DOOMMONKEY777]

Ok i know what ur talking about the bearing hitting sound comming from the engine under high stress low rpm and then goes away after 3k rpm, i have that sound 2 and my car only has an oil cooler, i belive its normal sound due to LOW rpm HIGH stress, any engine does that sound Ex: my dad has a hybrid civic when he stops engine is off when he presses gas and he puts the pedal innnn the engine starts and allready in gear under immidiate stress low rpm u can also hear the bearing sound, but after it reaches higher rpm it goes away, it did that for the last 75k miles and still i hear it also so does my z since i bought it 18k miles.

Am not saying am an expert nor i know exactly what ur sound is, but the description maches.

Anyone plz correct me if am wrong.

[ZFLASH]

I may be experiencing this same 'sound'. I only have CBE system installed. The sound I hear is similar to the 'struggling rattle' sound of a clutch. It does not affect the performance in anyway, just an annoying sound. I tend to hear this on a hot day when i am cruising in 3rd at 2500rpm and suddenly punch the throttle and there goes the rattle until i reach 3000rpm and goes away. I also hear it on hard acceleration in 1st gear but again , it goes away once 3000rpm is reached. Its an on and off thing.

Your explanation seems to be on point. But just to confirm, could I be hearing the same noise as OP?

Originally Posted by DOOMMONKEY777

Ok i know what ur talking about the bearing hitting sound comming from the engine under high stress low rpm and then goes away after 3k rpm, i have that sound 2 and my car only has an oil cooler, i belive its normal sound due to LOW rpm HIGH stress, any engine does that sound Ex: my dad has a hybrid civic when he stops engine is off when he presses gas and he puts the pedal innnn the engine starts and allready in gear under immidiate stress low rpm u can also hear the bearing sound, but after it reaches higher rpm it goes away, it did that for the last 75k miles and still i hear it also so does my z since i bought it 18k miles.

Am not saying am an expert nor i know exactly what ur sound is, but the description maches.

Anyone plz correct me if am wrong.