EMMISIONS - GUNSONS GAS TESTER

[V8JOHN71]

My Discovery 1 V8 on carburettors failed its MOT on emissions, carbon monoxide level 3.71 versus Max limit of 3.50 failed it. Same thing happened last year I was lucky that time as there was a guy available to tweak the carbs. I have been looking at the Gunson gastester which according to the information will measure CO but also states it is not suitable for MOT work where a higher degree of accuracy is apparently required. However my thought is if you can get the CO measurement down below the MOT limit is a much higher chance of passing the test.
I will be very grateful if anybody has used one of these with success in preparation for MOT's and could give their experience please?

[stevieturbo]

My Discovery 1 V8 on carburettors failed its MOT on emissions, carbon monoxide level 3.71 versus Max limit of 3.50 failed it. Same thing happened last year I was lucky that time as there was a guy available to tweak the carbs. I have been looking at the Gunson gastester which according to the information will measure CO but also states it is not suitable for MOT work where a higher degree of accuracy is apparently required. However my thought is if you can get the CO measurement down below the MOT limit is a much higher chance of passing the test.
I will be very grateful if anybody has used one of these with success in preparation for MOT's and could give their experience please?

MOT etc would need to be a proper calibrated machine, with regular testing etc. That said, I wouldn't trust two machines to read the same given the heavy use they endure, and no doubt questionable maintenance .

So clearly they will have to add caveats in case anyone sets theirs with the machine, and then the MOT's is different.

But if you have a baseline of 3.7, and can replicate those same test conditions and use a meter to then get a reduction of say 0.7% of whatever baseline the Gunsons offers when first tried, then you should be ok either way even if it happened to read different.

Although if you could tweak the carb so it was a little leaner, you're pretty close already as long as going too far doesn't then negatively effect hydrocarbon readings.

Although it would be interesting to see how it actually measures. I'm sure I read years ago about one of the cheap ones like Gunsons, and it actually measured CO2, then estimated CO based on that...not sure how valid that approach really is. I guess it must be useful for something though ?

[stevieturbo]

https://www.test-meter.co.uk/kane-ega-4 ... DNhKuB2OTn

Or to some degree you can use a wideband kit, which is something worth having on the car anyway for fine tuning mixtures.

Mixtures, AFR, Lambda are supposed to correlate to CO, although this is not always the case. Ideal world kinda thing



Plus on a carb car, depending on carb/intake design and what cylinders are affected by adjustment, it can and is better to monitor mixtures on both banks when making adjustments, in case one is fighting the other so to speak, and only one actually needs adjusted.