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Failed NCT - Emissions

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KaTaLy5t
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Failed NCT - Emissions

Postby KaTaLy5t » Sat Nov 29, 2008 9:00 am

Alright lads had the NCT this morning and it failed:

Exhaust emissions
Low Idle
CO 3.40 vol% anything above 0.5 vol% is a fail
HC 0 ppm

High Idle
Lambda: 0.997 Should be between 0.97 and 1.03
CO 0.15 vol% Above 0.3 vol% is a fail
HC 40 ppm Above 200 is a fail

I don't know why the low idle CO is so high and the guy in NCT center said they can only find out what's wrong and not what's causing it. I haven't changed anything engine wise since May when it had it's last NCT and it passed no problems with the Kakimoto exhaust on it. The only thing I can think of that might be wrong is a sensor of some sort gone???

Hope some one will be able to help

Thanks
Ross

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KaTaLy5t
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Postby KaTaLy5t » Sat Nov 29, 2008 9:23 am

I've been doing a bit of reading on the net about this and everyone seems to be saying:

If the cat was faulty all the emissions would be wrong

It might be either:
O2 sensor
MAF sensor
Lambda sensor

Solutions:
Replace above sensors
Clean throttle body

Hopefully someone on here will be able to shed a bit more light on the situation :lol:

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moomoo
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Postby moomoo » Sat Nov 29, 2008 11:57 am

My car failed on co2 high idle on thursday. I was at .4 :evil: :evil: :evil:

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james1485
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Postby james1485 » Sat Nov 29, 2008 12:02 pm

CO 3.40 vol% anything above 0.5 vol% is a fail

thats why he failed.
Last edited by james1485 on Sat Nov 29, 2008 3:27 pm, edited 1 time in total.

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Damok
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Postby Damok » Sat Nov 29, 2008 1:39 pm

A bottle of Spectrum D its an injector cleaner, ITl lower ou emissions for the nct

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Noel
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Postby Noel » Sat Nov 29, 2008 1:52 pm

http://www.petercoopercarrepairs.co.uk/new_page_3.htm
Lots of tips on there to diagnosing whats wrong...
:roll:

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KaTaLy5t
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Postby KaTaLy5t » Sat Nov 29, 2008 2:45 pm

Cheers Noel.

So what I've gathered from that is.

If your cat stinks like eggs more often then not, you're running rich which can cause the CO to be high.

A dodgy lambda sensor might cause the CO to be too high.

As well as that if you check the voltage the sensor is sending back the ECU. Normal output voltage of the lambda sensor should fluctuate between 0.2-0.8V higher than this ie 0.8-1.2V means too much fuel.

High CO is also caused by a bad air:fuel ratio ie. too much fuel.

So a couple of questions:

If the air:fuel ratio was wrong would it not be giving the same problem on high idle?

Where is the connection from the lambda sensor to the ECU. I'll try test the voltage and see what it's putting out.

If the lambda sensor was dodgy would it not have the same problem on high idle?

BTW the cat smells a bit more than it used.

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Noel
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Postby Noel » Sat Nov 29, 2008 2:52 pm

Was the engine cold? i know when it's first started they run abit rich (closed loop) ...

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KaTaLy5t
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Postby KaTaLy5t » Sat Nov 29, 2008 2:59 pm

No it was fairly hot. I drove it a bit before I got to the center but they left it outside for about 15mins. The temp gauge was half way up in the normal position when I got out of the car.


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