Anyone know just what those removable metal "oversize pepper shaker" disks located between the exhaust manifold and the catalytic converters are for? They look like small flat 2 1/2 to 3 inch diameter manhole covers with holes in them. I imagine they are there to prevent the converter from becoming clogged or contaminated but smaller carbonized fragments can still get through the holes anyway. I can't imagine large chunks flying out of the exhaust ports that would need to be broken up. It appears that perhaps 40 to 50 percent of flow is blocked by them.

It seems that removing them both would result in more power due to a less restrictive or congested exhaust stream. Has anyone does this and if so was there any noticeable change?

 

Do you have a picture? I've had mine out and my memory is not bringing up anything like you described.

What engine are you running? 2.5 or 3.0?

 

I've got the 2.5 gas engine, a 2002, automatic. Topaz like you wife's car.

My four photos show it laying on styrofoam, held in my left hand, in place in top of the converter inlet, and the converter without it in place. (Also a couple of shots of my pretty clean engine. The shot of one cam shows how clean full synthetic oil has kept it inside, no sludge.)

All exhaust flow must pass through these disks to get into the catalytic converters, they fit very closely matching a same-height indentation in the inlet. You can see the edge on the indention that holds it in place in the last photo, the inner-most ring. They are sandwiched in between the converters and their exhaust manifold.

They don't appear to form a seal and looks like taking them out wouldn't create a leak. Perhaps they merely prevent hot spots in the converter "matrix", evenly distributing hot gasses entering into the converters? Maybe there to keep a backfire/misfire from pounding the converter innards?

Sadly the engine you see pictured is the original engine now for sale on eBay. A local shop (not the dealer) told me my engine was seized. I bought a used engine and they installed it, calling me in the process to tell me my alternator case was corroded and broken in half. That was why the engine wouldn't turn over, a jammed alternator! Had they taken the serpentine belt off it would have started right up. Glad I kept the original engine instead of letting them keep it! I'd rather this one back in the car but I'n not going through the expense. There is a lesson to be learned here. If your Jag won't turn over, take the belt off and check it again. Their misdiagnosis cost me $5k.

 

Ouch! Holy crap, bro. That's malfeasance.

Anyway to your pepper Shakers... mine didn't have those. Those only look useful for causing rattling noises.

 

Larry,

I need to replace the rear upper Oxygen sensor but can't seen to be able to get a helper bar in place on my ratchet handle (no room) to get enough torque to get the bad one out. Would you know a trick for this or is this the reason you took your converters out, so you could get to the O2 sensors? I'm bugged about the check engine light and more bugged that it's running in "open loop" mode rather than "closed loop". Mileage is still pretty good but I'm sure I'm taking a small hit for that.

 

Changed mine last week, wound up cutting the heat shield and bending it back and then cut the wires off the old sensor so that I could get a good grip on it with a closed end wrench. That did the trick pretty nicely.

 

Thanks a bunch Larry! I'll go ahead with that after I've checked to be sure the heater has gone south, that appears to be the problem but need to check voltage to it first. If the engine is up to temperature and I clear the DTC and check engine light it stays off until a cold start. Obviously has output when hot, just no heater.

Thanks again, you da man!

 

I had my cats out because I took the engine out and swapped it. I took the cats off the old engine and put them on the new one.

As for cutting the heat shield you can do that or probably just remove it and get to the sensor. But be sure to put it back. It protects the steering rack among other things.