This is driving me nuts..
 

I have had a strange noise coming out from my muffler, not the middle one but the small one right beside it, on driver's side. The noise sounds like a whining sewing machine and it would only occur when engine is warmed up and idling. This is very annoying especially stop and go traffic congestion. Please help if you know what is wring with my car. Thanks,

I had a rattling noise i thought was coming from my muffler and turns out it was just a loose screw...Get under the car and check your bolts and screws....

I went under the car already that's how I figured it was that muffler has caused the noise. No loose nuts or bolts.

Hi,

If you've been underneath the Car and there are no loose screws or fasteners. And, the rattling noise is coming from a side muffler (Catalytic Converters), then the most likely cause is that your CAT has collapsed.

Inside the Catalytic Converter is a honeycomb-like matrix of individual cells. These are ceramic whose purpose is to chemically react with the Exhaust Gasses and alter them to less polluting by-products. Heat is an essential part of the reaction and these will run at over 900 degrees F.

Because of repeated heat cycles, as well as stress from bumps, and possible improper A/F Mixture, or just plain poor manufacture, this matrix can collapse.

When this happens, bits of the Matrix material can rattle around inside the CAT. Many will work their way through the exhaust to the Muffler, but many will not. The solution is a New catalytic Converter. A collapsed matrix can be so severe to restrict the Exhaust Flow, negatively impacting performance. If this is the cause, the only fix is to replace it.

But, I'm surprised that this condition wouldn't trigger the Check Engine Light as the O² Sensor Readings must be out of whack as well. Are you sure it's the muffler and not the Heatshield surrounding it? These use a sheet metal screw and the hole in the Heatshield can expand to the point where this sheet metal screw can no longer fasten it securely and it rattles. This type of problem usually goes away once everything heats and expands...

Happy Motoring!... Jim'99

"But, I'm surprised that this condition wouldn't trigger the Check Engine Light as the O² Sensor Readings must be out of whack as well. Are you sure it's the muffler and not the Heatshield surrounding it? These use a sheet metal screw and the hole in the Heatshield can expand to the point where this sheet metal screw can no longer fasten it securely and it rattles. This type of problem usually goes away once everything heats and expands..."

I am with Jim, check the heat shield first.

cat damage
 

If you suspect cat damage, check it out immediately. A common problem with the Toyota MR2 spyder was a poor cat. That engine was rock solid, but Toyota purchased and installed inferior cats and as they fragmented, parts were sucked back into the engine causing lots of damage. It is easy to check to see if the cat has collapsed, so I would do it before driving the car again

Guys, thanks for the response. I have checked it together with a mechanic friend w/o a hoist and he confirmed it is likely cat is shot because the heat shield seem nice in place. So, my question is is there a universal fit type of cat I can install or I should stick with OEM ones. And if you guys would know how much a OEm cat converter would cost . Thanks.

Hi,

What's you Model Year? It makes a difference...

Happy Motoring!... Jim'99

2000 2.7L 5 speed.

Hi,

The OEM Part you need is Catalytic Converter, Part # Right - 986.113.922.01 / Left - 986.113.921.01, cost from ******************************************** is @ $575.00 USD. You can probably find them a little cheaper if you shop around, although still gonna be spendy.

I believe that there are some High-Flow Aftermarket Units (they are 100-Cell as opposed to 270-Cell for OEM), but I don't have any information at hand for them. They are also probably more expensive and of course, you'd be required to replace both of yours if choosing this option. Hope this helps...

Happy Motoring!... Jim'99