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hi..
i get rattling noise whenever i tried to go over 3000 rpm mark.....everything is quite till 2900rpm then...the noise comes from the engine (?)...

once i go over 3000...the noise stops..

this is quite annoying...did anyone experience similar stuff??
 

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I have that same problem! I don't know what it is and it's getting very annoying.

For me it will go away after the engine has been running for a while, a long while...I don't know what it is, but it's going in to service...Again. You know, I've had more problems than not with this car...I think I'm going to unload it.
 

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yo! what's up guys?
the reason I found this web sight is cause I have that dam noise to. I'm hopping that someone has pin-pointed it. I know if I bring it in, they will say,"I do'nt hear anything" then I will be ticked. It does'nt do it until normal running temp or 15-20min when the whole block is heated up, but then it sometimes goes away after like 50min half the time. I had a car buddie ride with me and he was'nt sure if he heard it, he said "that it was probaly my octane breaking down at higher temps which are a usual for florida but I still think it's the transmission!!! When I stomp it in auto and hang my head out the window it comes form the center of the car more than the direct front but I could be wrong. reply if you guys have any input now I have ****ty paint,ecu,trac chip,under cage on right side and possible tranny ping. Do I have to say more????????? B
 

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I have the exact same germlin!!! I finally got the tech guy to acknowledge that he heard the sound too. He said he was even able to duplicate the knocking or rattling noise on the Operation Manager's IS 300.

"Ok, so what are you guys going to do about it?" He said basically there's nothing they can do since I already had the ECU re-program/update. He offered to do the TRAC update but specified that this update was not intended to deal with the rattling noise I was experiencing, therefore, he wasn't sure if it would fix the problem. Another possible downside to getting the TRAC update is that the car might be a little more sluggish off the line since the TRAC update is designed to smooth out the gear changes (transmission).

I was afraid to get the TRAC update since there's no telling what the outcome would be and I couldn't change it back to the way it was if I didn't like it.

While the knocking/rattling doesn't seem to effect the performance all that much it is extremely annoying as hell! If anyone out there knows how to solve this problem please let me know.
 

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If its a metallic rattling i'd say its a heatsheild, coming frmo the center of the car most like the heat sheild on the catalytic converter.
 

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Heat shield? Like what a screw is lose somewhere? Is that something I can check/fix myself or would you recommend taking it to the dealer?

As added info, mine occurs under hard acceleration from a standstill - from 1st to 2nd or 3rd gearshifts in either shiftmode. The noise appears to go away (at least a little bit) after continued hard driving - 30 mins or more........
 

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i have this exact same problem(among others) and have taken the car to the dealer 3 times now. I try to replicate it with a technician in my car...but of course the damn car would never be that cooperative. Mine usually happens after about 10 minutes of high speed driving on the highway and almost sounds like the little trip meter button is rattling. It's getting on my nerves sooo badly. I'd hate to be a traitor to the IS 300 community, but I am seriously thinking of getting rid of it.
 

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Hey TJC,
I got your e-mail, eventually we will all figure this thing out if we keep posting it. Now that I know everyone else has it, it makes me kookoo when ever I hear it. Tonight a smoked an integra (98-99?) with exhaust rims and misc stickers and that dam noise took away my car and a half lenth winning glory. He gave me a thumbs up as he turned at the next light but I was'nt smiling just grinding my teeth at that dam chatter. If it is a heat shield I will be stoked but I still look to the tranny. You had a good point too, I do'nt want that trac chip next week if it's gonna make my shifts weaker than they already are. I called the rod millen shop out in Calli and they said sorry no kits for the IS only the gs300 I ask ed how much and they said like $1700.00. So i anyone has any info on how the trac chip reacts please let us know. Late B.
 

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it's probably a heatshield if it is a true rattling noise. if it is coming from the engine bay, then it isn't a heat shield. the main thing that someone needs to determine is the general area that it is coming from.
 

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The tech guy who drove my car didn't think it was the heat shield. He said the engine was SPARK KNOCKING???? But it's true the noise makes more of a rattling sound than anything. I've tried leaving the car in ECT mode for a couple days to see if that helps..... no dice! The dealer called me today and said they were going to try and get a regional (south) tech rep to come out and investigate the problem. BTW this problem started happening at approx. 4,000 miles.
 

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thats bull. spark knock kind of sounds like a cat purring very fast at the speed of a machine gun firing. (ya i know that sucks, but that is the best i could come up with) .


Originally posted by TJC:
The tech guy who drove my car didn't think it was the heat shield. He said the engine was SPARK KNOCKING???? But it's true the noise makes more of a rattling sound than anything. I've tried leaving the car in ECT mode for a couple days to see if that helps..... no dice! The dealer called me today and said they were going to try and get a regional (south) tech rep to come out and investigate the problem. BTW this problem started happening at approx. 4,000 miles.
 

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I still think it can be heat shield of cats under the hood. Mounting points of them just rust through by years.
Try to tap those heat shields with something and see if rattles. Seems that this 3000 rpm makes resonance which causes the rattle.
 

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Just to clear something up

Hey guys,

So I see a lot of thought about the heat shields on the cats, and I think my car's configuration might clear a few things up.

My '04 is300 has Megan Racing headers installed (therefore, no cats or heat shields) and I also experience this weird knock at 3000 RPM.

As to what it actually is, I have no idea, but I'd love to figure it out!
 

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I spent a good 3 or 4 hours today running diagnostics. The rattling sound i determined comes from the back side of the motor. I got the best results at the back of the valvetrain. Also noticed the throttle bodt rattling as well. My car does it from about 2500rpm up to 3000rpm. Cruise control set at 75 and i wanna rip my ears off lol. Gonna spend all of sunday with a stethescope and see if i cant get a better location.
 
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StevenDriscoll
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