Anyone ever have a really really annoying rattle at about 3500rpm? Under light-moderate throttle pressure my car makes this really annoying "BABABABABABAAA" noise. The tone of the sound changes with the engine RPM and it is also dependant on whether you are accelerating or engine braking. It goes away if you push the gas down all the way. It also seems to happen more on rough highways than smooth ones.

I thought it was the intake, so I put on a different short-ram, which still did the same thing. The short-ram doesn't fit perfectly, but the new filter is made from a softer rubber than the old one, yet the sound of the rattle is exactly the same. As an aside, what is a good intake that fits a B18C1 swapped EG perfectly? Stock GS-R airbox?

It only does this under load, so it's hard to see what's actually going on. Could it be my exhaust hitting something as the engine moves slightly? It doesn't sound like it's something internal to the engine, and the engine runs perfectly (no CELs, idles fine, hits VTEC, revs to redline smoothly).

It's driving me nuts, and my car is in the rattling RPM range between 60-70mph on the highway, which makes it almost unbearable to drive (some crackhead stole my stereo a month ago).

Any ideas?

 

probably your exhaust. get under the car and tighten everything up. one of my header to cat bolts fell out and i had a bad rattle for a few days at like 1K which sucked when i the car was cold and idling

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tatakai &raquo;</TD></TR><TR><TD CLASS="quote">probably your exhaust. get under the car and tighten everything up. one of my header to cat bolts fell out and i had a bad rattle for a few days at like 1K which sucked when i the car was cold and idling </TD></TR></TABLE>

Anything in particular to look for? I have to get the exhaust worked on anyway since it's rubbing against my shift linkage.

Ugh the car is so close to working perfectly.

 

bump bump

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tatakai &raquo;</TD></TR><TR><TD CLASS="quote">probably your exhaust. get under the car and tighten everything up. one of my header to cat bolts fell out and i had a bad rattle for a few days at like 1K which sucked when i the car was cold and idling </TD></TR></TABLE>

X2

There is a heat shield right above the catalytic converter, this one has a tendancy to rattle from the exhaust heat.

Another heat shield near the actual muffler is another rattle prone spot.

Maybe jack up the front wheels and have someone get it up to 3500rpm and listen more to try and locate the issue.

 

Thanks :D Before the swap, my heat-shield used to rattle, but it was around 1500rpm and not nearly as loud. *shrug* I'll take a look later today.

This jack up the front wheels and get it up to 3500rpm in gear idea sounds like a Ferris Beuller style disaster waiting to happen!