m.o.t fail, your thoughts?

[Jehuty]

right guys, way back after i bought my 182 i had to replace the exhaust as it was a bit fubar, i opted for a ktr ultra exhaust, shortly after that a tear appeared in the collar of the standard cat and this also had to be replaced. i couldnt afford a new cat so ran a ktr ultra decat pipe for 6 months.. with no sensor attatched as it was stuck in the old cat.

anyway 2 weeks ago i figuered my mot was due and it was time to pay out and get it sorted, i bought a ktr ultra sports cat which is mot passable, i had it fitted by a garage and they even managed to get the snsor out of my old cat and refit it to the new one.

so mot time this morning, my car passed its fast idle test but failed its natural idle test

the max limit of carbon monoxide % volume at idle is 0.500, mines 1.840. i have no engine management light on at all, it was on obviously while decat was fitted but turned off hours after it was replaced with sports cat


i explained to the tester that i had just had a new cat fitted and asked what his thoughts were, he suggested a fault with one of the sensors, so tomorrow im paying 50 quid plus vat for a full test of the sensors etc to find the problem, however i am slightly apprehensive that its going to cost me a shed load more money to fix, any thoughts on what the problem could be guys?

 

[Alex H]

Was the car warm when the idle test was carried out? I seem to recall something about the emissions being higher if the car is cold. Could be BS though.

 

[Jehuty]

yea it was warm, and that is also true, id just driven it there and it sat with the engine off for no longer than 15minutes and then it was on idle for a good 10minutes before he carried out the test, i dont think it would have cooled that much it was a good 15minute drive to the test centre.

 

[maupineda]

I'd get a second hand OEM cat, sports cat tend to fail emissions. I bet there is nothing wrong with your sensors. New filter and plugs may help depnding on how bad are your currents.

 

[Alexjfinch]

From my experience with some of the sports cats they fit on the Zetec S (Ford I know) you have to take the car out for a right blast can get the cat cooking before it'll pass a emissions test.

Something to consider, however I don't have any experience with the Clio Sport Cat's and they could be completely different.

 

[jaysjetski]

running a car on idle for 10 mins plus would make the emissions worse, did he rev the car at all to try and get it to pass?

some testers know to give the car a blast out before the idle test.....

 

[Christopher.]

dont say that, iv got a ktr sport cat and the MOTs up next month

 

[MarcoB]

Give it an italian tune up!!! This post needs stickying in response too all failed emmissions tests!

 

[Alastair.]

when petrols fail emissions , i wak a fuel cleaner down the tank, 2nd gear up the road, come back and bang, straight through the emissions

 

[DannoTheGreat]

like ali said,
fuel cleaner in there an blast the s**t out of it in second an third. it'll clean her right out

 

[JonC]

I had the same problem at my last MOT, high CO and hydrocarbon readings. Took the car for long thrash to make sure the CAT was really hot. Passed on the re-test no problem.