MOT Emissions fail

[danjama]

Hi all, passed on everything except fast idle test CO reading.

Came out at 0.59% and 0.69% on second attempt. Limit is 0.3%. Passed previous year on 0.24%.

What could this be? Car is stock except for a K&N induction kit with pipes and sensors in correct locations.

Tester said this is probably due to overfuelling, which makes sense as my fuel consumption can be terrible.

I had a set of stock alloys in the boot at the time. Would this have affected the reading, due to the car sensing it was under load or something?

Please help!

[Ryan6926]

Did you reset the ECU when you fitted the induction kit? If not it's possible it'll be sending the wrong air fuel mixture through I'd suspect although if it's a panel filter it shouldn't make too much difference. If it's a cone then it may partly explain. If not then I'm thinking either Lambda sensor maybe faulty or the cat on it's way out?

[danjama]

Hi no I didn't reset the ecu after. How do I do this?

I dont think its the cat as the hc are very low.

[Ryan6926]

Just disconnect the battery for a few minutes, Pop the battery back on, take it for a run to get the ECU to 'learn' and it should adjust the fuelling etc to compensate for the mods that are done

The only issue with doing this is it could go either way, It could / should adjust and put less through but there's a possibility it could go the other way

[Nic]

Poor emissions and poor fuel economy, my guess would be the oxygen sensor needs replacing.

[toxo]

Or the ECU's water temp sensor is rotten. Happened on my MK2. What's your idle speed like, is it always a bit high?

[danjama]

Or the ECU's water temp sensor is rotten. Happened on my MK2. What's your idle speed like, is it always a bit high?

Warm idle is a constant 750rpm.

[Ryan6926]

Or the ECU's water temp sensor is rotten. Happened on my MK2. What's your idle speed like, is it always a bit high?

Mine's about 850-950 is it normal?

[MR2 Rich]

I've just ordered a new ECU temperature sensor because mine looks knackered, my idle is about 600-700rpm but does fluctuate, hopefully it will solve it as I think it's meant to be about 800-900rpm when warm and about 1100-1200rpm when cold?

[MR2 Rich]

Would just like to add a question, how do you fit a set of alloys in the boot of an Mr2????

[danjama]

Stock set went in nicely

[MR2 Rich]

Just realised you meant without tyres....