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[smalt36]

Hi all, been trying to get my 2.2 through emissions for MOT, has high CO, just found a 2-3" crack in the manifold would this be a likely cause, garage said it was probably the CAT. THanks in advance

[flyer 0712]

Very common on 2.2 omegas manifold cracking. dont know if it would cause the high reading.......my last 2.2 was a pig to get through every m.o.t.on readings.before the m.o.t i use to give it a service and add a can of cat clean and then blat it down the motorway on the way to the m.o.t and that made it better to get through ,,,,,,and i started using shell .v.power and i am sure that although being dearer it made a difference and i got more m.p.g. so it kind of evened itself out....

[smalt36]

Yeh just been reading its a common fault, gave it new plugs, oil flush and oil change which then passed natural idle test but still failed fast idle. They were on about doing a cat flush do you think its worth it? was gonna be £100 ish? or is it something you can buy off the shelf? Thanks for the help.

CO needs to be =<0.3% and is currently 0.68%

[PhilRich]

As flyer has mentioned, giving the car a spirited thrashing immediately prior to the mot to get everything good and hot can really help with emissions readings as long as there are no obvious problems such as blocked breathers, dirty throttle body, inlet manifold leaks etc; the leaking exhaust manifold will cause raised emissions readings but the hot run should balance this to a large extent. Some swear by CATACLEAN, the link below is one source, and appears to be a cost effective remedy 
 http://www.ebay.co.uk/itm/CATACLEAN-CATALYTIC-CONVERTER-CLEANER-REDUCES-EMMISIONS-/110743912088?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item19c8d9fe98

[Kevin Wood]

A cracked manifold won't help, as it may draw air in before the lambda sensor. This will result in the fuel mixture not being accurately controlled. Not sure what this "cat flush" is all about, but for £100 I think I'd give it a miss.

It strikes me that the cat is probably Ok if it passes the natural idle test.

[flyer 0712]

Surely a  new cat wouldnt be that more expensive......have the manifold welded or replaced....there is one on fleabay...

[smalt36]

Thanks for the replys, left the car with the garage for them to investigate more because i'm struggling for time  but all they've deduced is its running rich I could have worked that out it if i'd spent more time on it. Tried the thrashing it thing after i did plugs etc. Have checked breathers, there not spotless but you can freeley blow through them? Will do throttle body then, do you think cataclean would help if its running rich? What else to look for?

[smalt36]

just serviced the throttle body, does any one know what the pipe with the tiny hole does as this was blocked solid, allcleaned out now and bottle of Cataclean at the ready so heres hopin!