emissions and the MOT

[jaytee1]

To the wedge collective, is there a safe way to adjust the emissions down for the MOT, then return to original settings once the torture is over? The last 3 MOT's I have had to 'take it out and thrash the tits off it' to get the figures down low enough to pass, but this is getting more difficult as the MOT is in a time slot, and if there is another vehicle in, your screwed

[shpub]

It depends on what the readings are. To reduce HCs, try retarding the ignition. To get lower Co, the mixture can be weakened. The car needs to be really warm so that the mixture is not being enriched and if that means letting the engine get warm so be it - that's what the tester should do. Access to a good analyser is essential to get the tweaks right as well. Everything else needs to be in tip top condition as well e.g. ignition, filters and so on.

You can also adjust the idle speed and that can work wonders as well. The limit is 1200 rpm btw. Above that value and it may well fail for excessive idle speed.

Alternatively, you can do as I do with a fully programmable ECU and simply adjust the settings to give what ever is needed!
Plug in laptop. Set up real time mapping mode and tweak till its OK. Job done.

[wedg1e]

For a car the age of the Wedges, the CO limit is 3.5% anyway. Even a fairly sh@gged engine can do better than that, so it's down to how much fannying around your injection has had.

[brap_brap]

If it fails are you allowed a grace period with the car still road legal to get it fixed?

[rev-erend]

wedg1e said:

For a car the age of the Wedges, the CO limit is 3.5% anyway. Even a fairly sh@gged engine can do better than that, so it's down to how much fannying around your injection has had.

Jay - 2 ways or looking at the problem.

1. There is something wrong .. hence why the high un-burnt exhaust.

This could be dirty / old plugs / bad leads, knackered dizzy, partically blocked injectors etc, etc..

2. All is OK it just has not been re-tuned recently.

You will need a co meter or a friendly garage will do.

My old flapper 400 SE has this problem - there is a mixture screw on the airflow meter but it has a limited range - if it runs out - you have to remove the top inside you will see a toothed wheel - mark the starting position with a marker pen. Move the wheel in relation to the sprint retainer - one of two notches.

Retest enissions.

If will either go high or low - so if it's higher - go the other way and retest.

You then need to reseal the top back on with a silicon sealer.

Hope this helps.