******* UPDATE *******

I've gone through a few more tanks of gas since it first started and it's still making the noise.

I finally got around to scanning my car and and noticed I'm getting 1-7* of knock retard under normal acceleration. The last time I scanned my car was about a year ago and I wasn't getting any knock retard at all, since then I haven't changed anything on my car. My car isn't throwing any DTC's. My long term fuel trims are okay, no change since the last time I scanned my car, that means no indication of an exhaust leak. My O2 sensors are okay. I also checked for any misfires and there aren't any on any of the cylinders.

Any ideas on what I should do? I don't even know where to begin. Thanks guys.

 

I have the same problem and somehow everyone went to this thread...

but anywho, i run 91 octane (i can't find higher then 92, and most have 91 at the stations) all the time and i keep hearing the noise too. It started to be just at idle but now it's not so much there but in the 1500-2000 RPM range. My engine as far as i know electrically and everything is in working order. It doesn't throw codes and i can't find anything wrong. I took my stethoscope to it and can only here the ticking noise when i'm listening from the passenger side strut/frame. Anywhere else such as the manifold, rocker covers, heads, spark plugs, none of that makes the noise but the motor mount does and everything from the mount, to the wheel. WHAT IN THE WORLD?

 

I don't know for sure but it sounds like it's not detonation if you're running 91+ octane. I would consider it being a bearing main or rod. That would also explain why a stethescope would pick it up on the mount and control arms, but not in the head or valve cover. If it was detonation I would think you would be able to hear it in the valve cover intake and head.

 

Rod's don't knock at idle or under a load unless they are fixing to window the block.
Mains will knock if ya hold the brake and torque it up but they have to be awful loose.
Ya got something else going on.

 

If u lived in a cooler climate, I would consider piston slap. Which is the piston rattling around in the cylinder. It usually only happens during cold climates when the block and internals go from cooled to hot and start shrinking and expanding.

 

I live in Texas so I think that can be counted out, it's pretty hot here all year round.

 

I live up north so yes i have cold climate, but this only happens when the engine is already warm and has been driven. If i turn it on and let it sit, it will never knock, i let it sit for probably 30 minutes or more but didn't drive it, then when i drove it 10 miles and parked it, i could hear the rattling noise. It only comes after i've driven it and i don't feel any noticeable loss of power.

 

im also having a noise similar to this. i also get a weird 'grinding'/rattling type noise when i blip the throttle while in neutral the noise is hard to explain

 

YOUR noise is most likely the throwout bearing on your transmission, pretty common with the t-56.....

 

so the best fix would to just go ahead and replace the clutch, throw-out bearing and pressure plate while im at it?

also, how does $650 for a spec 1 clutch, resurfacing flywheel and instal sound?

 

I am pretty sure the Spec 1 is basically just a stock replacemnt, but still an OK clutch. But $650 for everything still sounds like a very good deal. i'd do it.

 

I have the exact same issue that you guys are describing, off-idle at 1100-1400rpms, a metallic rattle.....it is not detonation, spark knock or what-ever, i have narrowed it down to the cat, the filler inside it is breaking down and at low rpms it creates a resonance that vibrates the loose honeycomb in the housing...

Now if any of you have brand new cats on your car you may have detonation, but at that rpm with little or no load the motor should not detonate even with 87 octane.

How many of you with this issue have original cats?

 

Can anyone actually help me? I don't mean to sound like an *ss or anything, but my thread really got hijacked here... I need help with my scan data.

 

sorry for hijacking the thread dude, but by relating to the problem, we can find more possible causes.

 

It's all good, I was just hoping someone could help me out with some scan data. Since I have a scanner I was hoping it would help narrow down the problem, I just don't know what to look for.

One of my cats is about a year old, the other is several years old. I have already replaced each one due to the filler breaking up, so I know what that sounds like and don't think that's the issue right now.