Scraped through emissions. Anything to worry about?

[V88Dicky]

It took six attempts for my friendly MOT tester to get the 'Ro through it's emissions today. Am I needlessly worrying, or is there anything that needs to be done? Perhaps the car needs a tune / re-map?

VZ CV8 with tubular headers, 100 cell cats and full cat-back with x-pipe. Standard factory tune.

If there's any tuning / mapping gurus on here who can decipher the emissions results I'd be eternally grateful.

Lambda at fast idle seems to be out of spec?

[stevieturbo]

Possibly very slight air leak in the exhaust, cat not up to temperature or something.

But I'd say there is absolutely nothing wrong with the engine or tuning.

[Davep24]

your first run looks pretty good with the exception of the lambda being too high (too much oxygen)

the second run your CO has increased but the lambda has come down, this shows that the engine is responding to a lean mixture but the cats are probably working flat out

the hydro carbons on both runs are pretty much zero meaning you are getting full combustion.

if there was an exhaust leak pre cat then the HC would be high.

firstly i would check to see if your o2 sensors are switching over, if they are ok look for a leak in the exhaust downtream of the cats

HTH

dave

[V88Dicky]

Thanks Dave, will do

[ringram]

If its 100 cell cats then they sound non standard in which case perhaps the O2 are not in stock location? No doubt that will affect things.

You can mess with O2 switch points if you wanted, but IMO its better to run slightly lean anyway.