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[Field Marshal Dr. Opti]

........and if you answer "shove a stick up it's arse and see if it runs off".......then you're getting your household moggy confused with your catalytic converter.

I've been looking into this because if the RX-8 fails it's emissions test for a second time there is a possibility that the cat may be deceased.

1.When cold see if it rattles when struck with something solid.
2.Use an infrared laser pyrometer. This sounds expensive but costs about fifty notes on Ebay. Apparently it can check the inlet and outlet temperature of the cat. I believe it should be significantly hotter at the outlet if the cat is working properly.

Any other ways of checking to see if your cat is f**ked?, chaps.

[martin42]

try replacing it with a 2nd hand unit, maybe some of rx8 forums can help you out more 

[05omegav6]

try replacing it with a 2nd hand unit, maybe some of rx8 forums can help you out more 

If it's a common thing, good second hand spares will be hard to come by

The death rattle will tell you that either the heat sheild is loose or that the internals are breaking up

As a recent purchase, take it back to the vendor and suggest, politely, that under the Sale of Goods Act, it is rheir responsibility to sort and fix it

Unless you purchased privately, of course,

[Field Marshal Dr. Opti]

try replacing it with a 2nd hand unit, maybe some of rx8 forums can help you out more 

If it's a common thing, good second hand spares will be hard to come by

The death rattle will tell you that either the heat sheild is loose or that the internals are breaking up

As a recent purchase, take it back to the vendor and suggest, politely, that under the Sale of Goods Act, it is rheir responsibility to sort and fix it

Unless you purchased privately, of course,

I did, Taxi Al. I don't know anything for certain yet........but I'm hoping it's not the cat.

[Olympia5776]

........and if you answer "shove a stick up it's arse and see if it runs off".......then you're getting your household moggy confused with your catalytic converter.

I've been looking into this because if the RX-8 fails it's emissions test for a second time there is a possibility that the cat may be deceased.

1.When cold see if it rattles when struck with something solid.
2.Use an infrared laser pyrometer. This sounds expensive but costs about fifty notes on Ebay. Apparently it can check the inlet and outlet temperature of the cat. I believe it should be significantly hotter at the outlet if the cat is working properly.

Any other ways of checking to see if your cat is f**ked?, chaps.

If you decide to go down that route a couple of pointers .
The low cost handhelds on the market will have a fairly large target area .Read the instructions carefully to see what the "minimum target area" is in relation to distance from target . IR measurement is an average measurement of the area measured ( field of view ) so if the MTA is greater than the dia of the exhaust then you will be measuring the area behind which being cooler will greatly affect the accuracy.
Emissivity ,All IR measurement require this factored adjustment although many of the cheaper ones on the market ignore it.This is the compensation factor for the internal reflectivity of the target material ,ie the amount of IR that is reflected inwards away from the detector. To obtain any accuracy this adjustment has to be exact. The manufacturers will supply some figures but not for every surface in the world. Easiest way to overcome this is to paint the exhaust black at the point of measurement and then set the E value to 1 .
Pity you are so far away as I have several ,one of which will measure down to 9mm target , but that was a £3K instrument .
Good luck .

[05omegav6]

Hey ho fingers crossed Although I take it that it didn't run away when you got your stick out then...

[Field Marshal Dr. Opti]

........and if you answer "shove a stick up it's arse and see if it runs off".......then you're getting your household moggy confused with your catalytic converter.

I've been looking into this because if the RX-8 fails it's emissions test for a second time there is a possibility that the cat may be deceased.

1.When cold see if it rattles when struck with something solid.
2.Use an infrared laser pyrometer. This sounds expensive but costs about fifty notes on Ebay. Apparently it can check the inlet and outlet temperature of the cat. I believe it should be significantly hotter at the outlet if the cat is working properly.

Any other ways of checking to see if your cat is f**ked?, chaps.

If you decide to go down that route a couple of pointers .
The low cost handhelds on the market will have a fairly large target area .Read the instructions carefully to see what the "minimum target area" is in relation to distance from target . IR measurement is an average measurement of the area measured ( field of view ) so if the MTA is greater than the dia of the exhaust then you will be measuring the area behind which being cooler will greatly affect the accuracy.
Emissivity ,All IR measurement require this factored adjustment although many of the cheaper ones on the market ignore it.This is the compensation factor for the internal reflectivity of the target material ,ie the amount of IR that is reflected inwards away from the detector. To obtain any accuracy this adjustment has to be exact. The manufacturers will supply some figures but not for every surface in the world. Easiest way to overcome this is to paint the exhaust black at the point of measurement and then set the E value to 1 .
Pity you are so far away as I have several ,one of which will measure down to 9mm target , but that was a £3K instrument .
Good luck .

Thanks, Olympia. . I'll read the instructions very closely as you suggest.

[Lazydocker]

Opti, unless it's got a hole it's not the cat The only fail was lambda, so it's not the cat (unless it's drawing air in)

[Field Marshal Dr. Opti]

Opti, unless it's got a hole it's not the cat The only fail was lambda, so it's not the cat (unless it's drawing air in)

You might have just saved me £1300 ( that's what Mazda charge for a genuine cat). Thanks LD.

[Lazydocker]

Opti, unless it's got a hole it's not the cat The only fail was lambda, so it's not the cat (unless it's drawing air in)

You might have just saved me £1300 ( that's what Mazda charge for a genuine cat). Thanks LD.

The cat is doing it's job

[henryd]

Opti, unless it's got a hole it's not the cat The only fail was lambda, so it's not the cat (unless it's drawing air in)

You might have just saved me £1300 ( that's what Mazda charge for a genuine cat). Thanks LD.

The cat is doing it's job

I agree,I still reckon you have a very tiny exhaust leak which is messing with your Lambda reading

[Kevin Wood]

Yep, categorically, it's NOT the cat.

It only failed on the Lambda reading, which is an estimate of what the fuel mixture was upstream of the cat. The cat is there to remove oxides of nitrogen, carbon and hydrocarbons. Its effectiveness in this respect is measured by the CO and HC levels in the exhaust gas, both of which were within limits on the report you posted.

[Darth Loo-knee]

Usually the heart has stopped

[Field Marshal Dr. Opti]

Yep, categorically, it's NOT the cat.

It only failed on the Lambda reading, which is an estimate of what the fuel mixture was upstream of the cat. The cat is there to remove oxides of nitrogen, carbon and hydrocarbons. Its effectiveness in this respect is measured by the CO and HC levels in the exhaust gas, both of which were within limits on the report you posted.

Thanks, Kevin. You seem to know what you're talking about so I'm going with you on this one. I've booked it in for  another MOT on Friday. I've asked them to check for exhaust leaks while they have it up on the ramps, as this could be the reason for the  slightly high (1.12) lambda reading. Could the Lambda sensor  be faulty?

The reason I've been banging on about cats is because the RX8 forum say  the main reason for emissions failure on these cars is faulty ignition coils  causing the cat to fail. Does that make any sense?

As you rightly say both CO and HC levels were well within guidelines.  Just a fail on the Lambda.

[Kevin Wood]

I would expect with an ignition coil problem you'd get a misfire. If that were not corrected soon (and if it was only the leading / trailing plug it might not be that noticeable) you would get hydrocarbons passing into the cat in large quantities which would kill the cat, so that story is plausible, but I would expect the HC level to have been the problem at the MOT not the Lambda.

The Lambda value just indicates that, based on what the test machine is seeing coming out of the exhaust, the engine is running a little lean. This is just an estimate based on the exhaust gases after the cat, though, so could easily be upset by air leaking in. Alternatively, it may be that the engine is really running lean, which might well be down to a failing lambda sensor, air leak or some other metering issue. Live data would be required to dig much further than that, TBH.