Another MOT Failure (Emissions) - Saxperience

adsprojects · 20th November 2009, 18:43

I’m starting to hate my VTS ...

MOT today failed today due to CO emissions being 9.2 (0.30 max) CAT was changed only a few months ago, front lamber changed today as it was suspected faulty, however failed for a 2nd time.

Could the Lamber after the CAT also cause the high CO reading? The garage tell me not it would just be the front one.

Any ideas or advise would be good as i don’t want to spend hundreds on them fault finding.

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adsprojects · 20th November 2009, 18:58

Forgot to add, she has a few small mods.

Raceland forced air induction
Full CAT back jan speed exhaust

Did have a jan speed mani , however this was a 2" bore and was blowing as cat inlet was only 1.75". CAT was changed for a 2" bore but was still blowing so i replaced this with the standard a few months after. CAT was also replaced at this time.

Thanks all,

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mossy_1991 · 20th November 2009, 19:01

just go to a garage an ask if any mot tester is up for doin a dodgy mot an pay him a little extra on the side.. save spendin loads on tryin sort the problem out

wadoryu · 20th November 2009, 19:01

some of the gases might be getting through due to the change in sizes? or have i read it wrong

GRAHAM2000VTR · 20th November 2009, 19:02

i find at work 9/10 times it the rear lambda sensor at fault the last 3 saxo ones iver done have been rear sometime front on other but allways rear sensor on saxo

adsprojects · 21st November 2009, 10:36

Thanks for all your replys.

I have been doing some research and think it could be the following:

1) Bad rear lamber sensor
2) leaking manifold gaskit

would 2 result in a CO reading that high?

And is a CO reading that high common?

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St_James · 21st November 2009, 11:50

If the mot tester is any good he should get it through really if you've changed everything you can. Mine went in yesterday for MOT, we spend 40 mins on the emissions to get it through. Failed first time as it didnt seem that the cat was working at all, but after a few changes with the revs, running the long test etc it came down to below max. Quite often it can fail on a cold engine, different revs etc. I'm still going to change my cat anyway cause it isn't performing as it should.

saxo-parts · 21st November 2009, 12:08

why should an mot tester pass it just because everything has been changed? if its out of limits, its out of limits. could always try forte cat treatment, its worked many times for us in the past.

adsprojects · 21st November 2009, 12:37

Well, I think I'm going to have to start from the top.

Full service, stock air filter , stock exhaust , rear lamber , manifold gaskit then CAT again..

It passed last year so it must have been my pissing around with the exhaust. That's why I'm hoping it's nothing mayjor. People have said above 4.0 is bad however mines between 7 & 9.

The garage I use don't do MOT testing, so that just adds to the problem. Might take it somewhere else.

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Xsi16v_Jk · 22nd November 2009, 09:34

A complete standard exhaust system and catalyic convertor will help alot mate, get them red hot before the MOT.

From your emmision being 9.2, thats very high considering you have no cams etc..

Saxo_Scott · 22nd November 2009, 09:43

replace the 2nd sensor, add some redex and take it for a good blast before the next mot

GRAHAM2000VTR · 22nd November 2009, 10:12

would worry changing exhaust etc as aboth change rear labda give it a good run before going making sure its hot and im sure it be fine

Liam_ · 22nd November 2009, 10:39

The second lambda (after CAT) doesn't alter the fueling in any way - merely checks the CAT is working to an efficient level.

I would dismantle the throttle body and clean it along with its sensors. Also give the MAP sensor a clean - that's bolted to the left side of the inlet manifold. Give it a full service (with a clean air filter!) then give it a hoofing before the retest. Would be very surprised if you still have trouble then.

adsprojects · 24th November 2009, 19:36

Hi lee,

Well after quote alot of messing around we have found the CAT is not getting up to temp, Manifold is running at around 190 while the CAT is just 60 -100. The cat on the car is one of £100 jobbies. Garage want a OEM CAT to test so we can prove to the guys that provided the "as good as" CAT its there fault.. Anyone know where i can get a OEM CAT to test in East Sussex ??

I know that above might not make sense but im in a rush