MOT Emissions advice

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AlsV
Posts: 1
Joined: 24/05/22 22:06

MOT Emissions advice

Post by AlsV »

I'm after some advice. My 2002 MR2 has failed it's MOT carbon monoxide emissions test. It's been close to failing for a few years now but has previously just managed to scrape through.

The advice from the garage is not to waste my money and just sell the car for parts or to an enthusiast. I'd rather keep the car but don't want to get into the situation of paying out lots for it still not to work then trying something else etc etc. Any ideas on what I might need to do to get it fixed and what the sort of costs involved might be (parts plus roughly how much labour time)? I'm pretty ignorant about the mechanics of cars so would need to pay someone rather than doing the work myself (and my garage charges around £100 an hour). I've heard mentioned O2 sensors (the garage said that they could try changing these but it might cost lots and still not work), catalytic convertor, exhaust, engine?

The car has been unused for a few months now since it failed and I need to make a decision as the tax is now due soon. If I could have any idea of what sort of cost I might be looking at then that would help. Obviously nobody will really know without looking at the car but it appears that there is a lot of experience on this forum.

The readings are:

Fast Idle Test:
Speed Not checked
CO 0.42 %vol (Fail)
HC 31 ppm (Pass)
Lambda 0.99 (Pass)

2nd Fast Idle Test:
Speed Not checked
CO 0.38 %vol (Fail)
HC 13 ppm (Pass)
Lambda 0.99 (Pass)

Natural Idle Test:
CO 0.04 %vol

I had put some cleaner in a day or so before and driven it hard just before the test so the engine would have been relatively warm.

Thank you!


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jimi
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Re: MOT Emissions advice

Post by jimi »

The advice from the garage is not to waste my money and just sell the car for parts or to an enthusiast. I'd rather keep the car but don't want to get into the situation of paying out lots for it still not to work then trying something else etc etc.
For a start I'd find another garage if that's all the advice they can offer :facepalm:

When was the car last serviced ? Plugs, oil, air filter changed ?
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JRD93
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Joined: 08/03/21 19:10

Re: MOT Emissions advice

Post by JRD93 »

That's hardly a fail, pretty sure a pass is 0.3% on CO2. To put this into prospective mine was around 2% on the fail a good factor over yours, turns out a vacuum line was not connected, what idiot would do this ;)

You're best off doing what Jimi suggested above, change the oil, plugs and air filter. Check for vacuum leaks. Also worth putting some cleaner as you say with a low tank of petrol and giving it a good blast till nearly empty then filling back up with some premium petrol.

When you say it was relatively warm, you want that cat to be like lava. I blasted mine in third gear like 4-7k rpm. The cat works best when warmed up and will also clear any polutants and gunk you've dislodged with the cleaner.

In the end I had to replace the cat as it was the original and was barely working, I would really suggest doing all the above before tackling the cat as I had to buy a new exhaust and nearly a downpipe as they had rust welded themselves together. All of the above can be done really easily with guides online or ask here if you get stuck.
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