Emissions And Cats

[Anthony 1,003]

Took my S16 in for its MOT this morning and it failed on emissions, rather badly at that

 

I'm assuming that it's the CAT that's at fault, but thought I'd check before spending money as according to the history I got with the car it only had a new CAT fitted about 3 or 4 years ago and I'd have thought that one should really last longer than that.

 

The results were...

 

Natural Idle (827rpm):

CO = 4.27% (limit 0.50%)

 

Fast Idle Test (2371rpm):

CO = 1.04% (limit 0.30%)

HC = 62ppm (limit 200ppm)

Lambda = 1.00

 

Second Fast Idle Test (2531rpm):

CO = 1.27% (limit 0.30%)

HC = 47ppm (limit 200ppm)

Lambda = 0.98

 

Given the lowish hydrocarbons it looks like it's burning fuel cleanly, and the lambda sensor I assume is working OK by the fact that the car gets reasonable fuel economy and the mixture readings from the machine look sensible (and again, like the CAT the lambda isn't that old). It's just the fact that the CO is sky high, to the point that it would fail a non-CAT test, that's the problem - sound like a classic CAT failure to people?

 

The other question is if the CAT was removed altogether, is it likely that the CO would fall to the point that it would pass a non-CAT test (ie below 3.5% at idle) since there's no mixture adjustment available?

[Richie-Van-GTi 71 2 Cars]

does sound like a cat failure, removing the cat would probably increase the emmisions.

[Garry 1]

Don't flame me but from my very limited knowledge:

 

As long as the lambda reading is near 1 it is OK.

 

It may be the CAT causing the high CO emisions or the Coolant Temp Sensor, if it is faulty the car thinks it is running cold and therefore runs richer, although you say the economy is pretty good. I changed my CTS and the CO dropped from 9% down to 3.7 ish.

[Miles 331 1 Cars]

It's not uncommon for a CAT to fail this quick depending on how it's been treated, The average life is 5 years or so I'm told by most Dealer's and not all Pug ones at that,

Give it the tap test to see if it's gone hollow and be wary of these cheap £80.00 cat's as they are rubbish for any performace engine, a OE one if the way to go. Don;t forget you can get about £25.00 for the old one if it's got the internal at your local scrappy.

I've got a CAT coming off my S16 anyday, It worked last MOT and hasn't been run since and I think isn;t that old.

[Anthony 1,003]

Just checked the paperwork - CAT is 3.5 years old and the lambda is 2 years old

 

Bono's being kind enough to lend me a spare CAT and lambda of his so that I can swap them both over and see what's at fault and get the car through the MOT - if it does turn out to be the CAT, then I'll probably drop you a PM to see how much you want for yours Miles

[Miles 331 1 Cars]

Can't you just stick a can up the exhaust trick so the probe measure's nothing!!