Non mini question
Turbo Mini Forums

first of all i don't like injection systerms. right on to the question, My mx5 will not pass its MOT been down twice and it still failing on emmissons. Co and Hy are fine but the lambda is to high. I've changed the lambda sensor in the exhuast and its made NO diffrences, Im not £50 out of pocket and the car still won't pass. mite rip the lot off and fit carbs..

HELP!!!!!!

Well, carbs definately WON'T pass, so take that silly idea out of your head LOL!

I don't fully know what to suggest - as i don't understand the current testing; but if the CO is right, then isn't the rest down to a faulty cat?

Leaky exhaust

air leaks in intake/exhaust...or an odd sensor reading...

Or there could be plain and simple mechanical inefficiencies somewhere.

IF CO and HCC/NOx are fine, the CAT is probably ok.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

had a problem similar to this at work, car wouldnt pass we initially thought it was the lambda sensor (which is was as well) but the cat was a non genuine cat so wasnt good enough for the car. replaced with a genuine pug one and it passed

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

Low CO And Low HC and High Lambda could mean its running lean, But it could also mean that its actualy running right; With a leaky exhaust after the Lambda sensor, oxygen is drawn in and the Gas Analyser registers it as lean.

If there was a leak before the Lambda sensor, the Engine management system will add fuel thinking the combustion is lean when in reality its not. In this situation the results would be High CO, Low HC, High Lambda.

Remember, all that Lambda is is a factor, it is the Stoichiometric air fuel ratio 14.7:1 divided by the actual air fuel ratio, whee perfect combustion is lambda 1, rich is 0.86 and lean is 1.27