Help with MOT emissions fail

[wehey]

i have just got back for the Mot and the only fail I had was emissions.

A little history since the last MoT?....
Swapped out the 1.0L for a low miler 1.3L (40k auto block)
I still have the 1st cat but recently fitted a Sported exhaust which deletes the 2nd cat.
I have a spare lambda, original exhaust and spare 1st cat in the shed.

Now as far as I know you should be able to pass the emissions with just the 1st cat.
So my options are:
Swap my 1st cat and lambda for my spares and hope they are ok
Re-fit the original, stock exhaust
Do both of the above just to be sure.

Below are my readings. What should I do next folks? Can anyone tell from the readings what could be at fault?

 

[Agent_Sm1th]

I'd check for a leak in your exhaust system by sticking your hand over the tailpipe and listening for leaks. Unless you've got super long arms you may need a helper.

 

[wehey]

Thanks for the reply
I have been doing a lot of reading trying to interpret the results and come up with a solution.
From what I have learnt, I agree that there is probably a leak in the exhaust somewhere (especially as I fitted it myself on the driveway lol) after the Lambda which is giving high mot lambda fail due to excess oxygen in the exhaust being picked up by the mot sniffer.
The high CO reading is normally due to a rich mixture and the high HC, although it has just scraped thro, can be caused my unburnt fuel or incomplete combustion or a need for an oil change etc. Both I guess will be exaggerated more by a naff cat?
All of the above may be complete b*****ks tho lol

 

[TonySLX]

Mine failed much the same as yours a few years back and was a very small leak at the back box..... Have you fitted a crush washer between mid pip and back box as I have just replaced the backbox on mine again, and didnt have a crush washer ..... used some gasket seal but it was still blowing a bit..... so had to take it off and shove the crush washer in yesterday........ Any small leak or blow by will likely be the reason for the fail.
BTW smear the exhaust with exhaust gasket seal and then position the crush washer into that .... otherwise it just keeps moving out of place when you try to bolt it up...... bstid thing

 

[wehey]

Thanks Tony. It's a Sportex exhaust that I fitted and all the sections are a flanged fit, so quite herd to get a good seal. It's a real nightmare to fit it all whilst laying on the driveway!!!

So far I have changed the exh mani back to a Frank Jobbie so that the lambda reads from all 4 cyclinders, fitted a spare cat, changed the throttle body back to stock, new plugs, oil change and new lambda. Hopefully that will fix up some of the readings and it definitely drives much better. I have a feeling that the Maf on the throttle body I was using was a bit naff as it instantly felt better once I had switched back to the old one.
Booking back in for a re-test on Tues. if still a fail then the stock exhaust will have to go back on for a while

 

[TonySLX]

This was the one i used for the mid pipe to back box ..... http://www.ebay.co.uk/itm/290613166176?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT


has done the job and if you havent got one in there its gonna blow causing problems ......

Know exactly what you mean about laying on floor trying to get this done up .... and i was only doing the back box lol ....... didnt help that i waxolyed the rear axle at the same time and ended up with that all over me as well ...... not so smart some days lol

 

[wehey]

Oops.....I meant to say that it's a swaged fit

 

[TonySLX]

I would get an assistant to elp you fit it then ..... can imagine the swearing trying to get that lined up on your own ..... let alone securing it ...

 

[wehey]

Well good news today......it passed

CO went from 0.74% to 0.175%
HC went from 195 to 22 !!!!
Lambda went from 1.061 to 1.012
The only thing I didn't swap was the exhaust lol

So the list of things I tried were:
Redex in the petrol
Oil change
New lambda
Swapped to another throttle body
Swapped to another 1st Cat
Swapped to a a frank exhaust manifold
Ran the Sportex exhaust with only the 1st Cat.

Happy days