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MOT Reduce Emissions - Quick Wins for X180

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My car failed its MOT on emissions (Halfords computer says No!) - it's only done circa 1500 miles since the last MOT and I'm wondering if there are some quick wins that will get me through a retest.

I've been using the higher octane fuel available at the pumps, not sure if this is a factor, so I will run this out and fill up with standard.

It's ticking over a bit faster than needed, so I thought I would reduce the at idle revs to be just enough to stop it stalling (I'm assuming this makes a difference?

I have some new plugs so will fit them, but no new air filters to fit on my after-market K&Ns or filter cleaner fluid (the car came with them and therefore doesn't have the standard air box), I'm guessing this may also have an affect affect on emissions and considering buying some replacements as existing a bit tatty.


Are there any other cheap quick wins that will help me get it through emission test - other than to give it a proper run and warm up? 

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Without even a new set of plugs, giving the car a good warm up up/down the A12 and using a small independent garage the car passed its MOT with just a warning about the join between the manifold down-

Have you got your CO2 and Hydrocarbons readings?   You are a brave man taking it to Halford/Kwikfit etc...   

You could always do what Ford used to do, and I believe a number of modern cars still do. Have an auxiliary air pump somewhere pumping air directly into the exhaust to thin out the emissions!

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I’d not trust them with an Esprit. Find an understanding independent mot station. They will take the necessary time on what is an old classic sportscar. It’s simply not the same as doing an emissions test on a Hyundai i10

Only here once

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Winding in the mixture screws a bit on the carbs could help you through. Standard set up is around six half turns (three and a half full turns) out on the mixture screws. I usually wind mine in a turn for MOT just to be sure.

That said I do use a little garage local to me who are classic friendly. On the last couple of MOTs they've spent as much time admiring and commenting the car as actually doing all the MOT stuff. Pretty sure they haven't even checked the emissions on the last couple 😐

Not worth starting anything now...🍺

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If your Esprit has a catalytic converter, yes THAT needs to be fully warmed up prior to the test. Run the engine at road speeds (NOT idling!) for at least 20 minutes prior to submitting it for the test.


I always idled my carburetted cars faster for emissions tests. Emissions testers are wise to that strategy here, too fast an idle (greater than 1500 RPM) and they will refuse to test the car. That, and leaning out the mixture just a little bit FIRST, as has been said. (Too lean and you will get misfires anyway.)

The new plugs will help.

Atwell Haines

'88 Esprit

Succasunna, NJ USA

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Thanks for tips - I regret using Halfords and will try a nearby independent.

There's no cat on my car, but turning the fuel mixture down a notch sounds like a quick win.

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  • 2 months later...

 Have an auxiliary air pump somewhere pumping air directly into the exhaust to thin out the emissions!

As did Lotus for the 80's Federal 910, driven off the exhaust cam and injected into the exhaust ports-  but good luck finding the parts anymore they've likely been binned.

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