slight rattling at 3000 to 3500 rpm

Shamrock

Hey guys I've been a lurker for quite a while but I question now. I have been driving for the fast last fifteen thousand kilometers with stillen headers, sport cats and an akropovich full system exhaust. I never did the tune because I didn't trust our local tuner and I figured the car would tune itself pretty well instead. So I finally got the nerve to tune the car and right before tuning it I emptied out the sport catalytic converters. The tune was a great success. I got 327 horsepower at the hub. I noticed however that when driving the car there is a slight rattling noise from 3000 to 3500 rpm. This only happens during acceleration and not while in neutral. It's barely audible but to a paranoid freak like me it's pretty loud. Could this be because of the empty sport catalytic converters? Perhaps something happened during the tune? Maybe the extra horsepower and the empty catalytic converters changed the frequency somehow and there is just something rattling and everything's okay? Thanks

90 ST

what kind of rattle? tinny metal? heavier then that? Could just be a heat shield came lose...

Shamrock

I don't think it sounds metallic. If I said like a rolling rattle does it make sense?

Shamrock

Any clue guys? I wouldn't know where to start to look for the problem.

Rusty

What do you mean by "I emptied out the sport catalytic converters."? Did you gut them out, so they have no honeycombs?

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90 ST

You got everything out of the stock cats?

Can you get it on video so we can hear it?

brancky3

If you gutted the cats there is typically a "rattle" (rasp) audible from around 3000 rpm.

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Shamrock

Yep. I gutted them (stillen sport cats.) Not sure if on a video you'd here over the engine/exhaust. Why though is there a "rattle" when the cats are gutted, brancky3?

brancky3

You get the same thing with test pipes, it's not actually a rattle but just more rasp in the exhaust from lack of cats. It's normal, assuming it's the same sound.

Does it sound like this car does around 19-20 seconds in?

https://www.youtube.com/watch?v=IDMtmLLcbRM

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Shamrock

I am not sure. Haven't listened from outside the car. Why only at around 3000 RPM? Weird...I also only hear it under load.

Shamrock

Well, while sitting in the car with the door open I do hear the noise from outside at around 3000 rpm while gunning it in neutral. The question is whether that raspy sound is what I'm hearing inside the car as well, because I hear it from the area between the dashboard and the engine and I don't here it when the car is gunned in neutral.....ok new thoughts. Now that I know what the sound sounds like I do hear it from the inside of the car but only after gunning it and only as the revs go down not as they go up. Is it possible that what I'm hearing while driving the car is a result of that vibration causing an internal noise in the cabin?

Shamrock

Sorry for bumping...anyone?

Masterbeatty

If you have something to take a video of it, then I t would be easier to figure out. But since its in that area, possibly a washer or the gaskets are flapping around on the cat tubes.

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James10694

Its most likely from gutting the sport cats. When I had my stillen cbe and test pipes I had the most obnoxious rasp/rattle between 2 and 3k rpms. It literally sounds broken. Yesterday I changed to fast intentions cbe no more rattle or rasp

Shamrock

I hear it from the inside of the car and its not the same sound as the rattle from the exhaust (which I hear.) Could it be that at that frequency the fact that I gutted the cats is causing some other noise? Some other rattling?