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Setting emissions with a wideband lambda
JekRankin - 22/1/19 at 10:01 AM

I'd prefer to avoid the expense of getting my car to an MOT centre to get the IVA emissions set up if possible!

If I use a wideband lambda gauge to set the mixture to stoichiometric at idle and fast idle, would it be an unreasonable assumption that the CO and HC emissions will also be in spec (providing my cat is working correctly)?

Jek

cliftyhanger - 22/1/19 at 11:12 AM

HC are more to do with balanced intakes. Single throttle body simple, ITB's need accurate balancing. Basically it is unburnt fuel....

But yes, a wideband or even narrowband can be used for setting emissions.

gaz_gaz - 22/1/19 at 01:34 PM

i tried what you are suggesting and failed IVA last week on emissions, Wideband said yes, Gas analyser said no.

there where 3 other small failures that I could have fixed on the day but sadly the emissions where a show stopper,
£90 re-test and another 150 mile round trip to the IVA station. I wish I'd given my local MOT centre 20 quid to check the emissions, You could also setup your headlight aim and check the brakes at the same time.

Good luck with whichever way you decide to go

coyoteboy - 22/1/19 at 03:09 PM

I mapped my 3SGTE with just a wideband, and it passed the MOT gas analyser CAT test without trying, but it's going to be sketchy.

jelly head - 23/1/19 at 07:58 AM

My engine had a really lean map specifically for the IVA, stoichiometric wouldn't hack it.

MikeRJ - 23/1/19 at 10:10 AM

quote:
Originally posted by jelly head
My engine had a really lean map specifically for the IVA, stoichiometric wouldn't hack it.


Running lean will shift the lambda value outside permissible limits (0.97 - 1.03) for a 1992 or later (catalysed) engine. It is also likely to increase HC emissions.

Daf - 23/1/19 at 10:46 AM

I tried this and faled my IVA, like someone above said - wide band said yes, IVA machine said no!

JekRankin - 23/1/19 at 05:44 PM

Sounds like you still need do do some adjustment on some set ups within the 6% range of allowable lambda to get the HCs and CO within spec. A trip to the MOT centre is probably called for!

JEk