i was fed up last year when my fd rex failed MOT on emmisions, after 7 years the MOT station reckoned it was on the VOSA database and had to pass the cat test....plus they reckoned the exhaust was too loud....new rules dontcha know.
the car had 2000 ppm CO with a 3 inch straight through system and petit ECU, basically twice the limit for a cat test.
To try a fix i bought the shortest, cheapest catalytic converter i could find on ebay. 3 inch diameter pipe and low cell density i.e. not much catalyst, see here http://www.ebay.co.uk/itm/410300-FLOWMONSTER-Catalytic-Cat-Converter-3-/140375059193?pt=Motors_Car_Truck_Parts_Accessories&hash=item20af016af9
The catalyst bit is at least 4 inch dia, and it doesn\'t look restrictive, you can see through the cells, prob about a mm square each.
anyhow, cut a long story short, it wasn\'t much bother to chop a section out of the midpipe, splice in the ebay cat and weld in a small tube before the cat to plumb in the air pump.
Result....40 ppm CO ( 0.004%) on MOT test and 50 ppm HC....a resounding pass...its a green machine for the cost of a £60 cat.
I don\'t have power figures so can\'t confirm any power loss, but this is about as high flowing as a cat can be and the effect on the emmisions was huge.
Im just running the airpump on my FC, no cats or anything, CO is 0.18%, just run the airpump and its fine
yes i tried running just the air pump plumbed into the exhaust on the FD , it didn\'t bring the emmisions down much at all.
0.18% is a fail on the CAT test for MOT. the FC are all non-cat test, so all good.
Nice result!
The cat test on my FD the limit is 0.5%co and 200hc (though the level gets more stringent post 95 i think
Dont know how but I passed this with a full decat a few times now, dont think I will be so lucky this time round, so may look into what you have done :)
Would like to get a controller (like a butterfly) in so I can run with a cat (pc plod mode) and also a straight through (no plod!)
Was the £60 all in with shipping and tax (if you got the import tax) ?
Nice info mate ;)
At those sorts of prices you should make them to sale. I would buy one if you made one and priced in a bit of profit for yourself ;)
the usual limits to pass the cat test are lambda 0.97- 1.03, max co % .30 and hc is 200ppm but its up to the vehicle manufacturer to say what the rpm is for example audi is higher than most at about 4000 to 4500 rpm, (most are between 2450 and 2950), but for some manufacturers the limits are different like volvo to name 1 the lambda readings have to be between 0.96 and 1.04 which is a greater margin than the norm
Ah I didn\'t know the manufacturer influenced it? The lambda I get tested on gets a max of 1.67!!
My decatted FC is still under the cat CO% then :) even without it having a cat for about 1 1/2 decades :D
quite often if your lambda is slow to react there is a build up of soot on the sensor and usually just needs a clean
lamda in the FC is only used for cruise, its not used on idle on mine :)
Hi guys, small thread hijack, what sort of HC levels are you getting with no cat? I have an rx8 that recently only just scrapped through an emissions test with HC levels of 160ppm (limit 200) the cat is only a couple of months old and the company who sold it to me are complaining that my high HC level killed the cat and that I clearly have an engine fault, any thoughts???