Pre NCT STP additives

ciscokidder

Bonzer - My petrol car is up for a nct on friday. In a pre nct they said it passed but emissions was borderline. Fail is 1.3 and it was 1.295 (!)

Presume they tested it cold so perhaps driving to the test place in 3rd might ensure its ok.

Does anyone know if its ok to add stp fuel additive to the tank so close to the actual test?

Marcus.Aurelius

If you add stp to hte tank, you may push your emissions past the acceptable mark. If you think about it, adding a cleaner to your car pre-nct with such short notice cannot but increase your emissions as the stp clears out some of the gunk in your engine.

What part of your emissions were high? CO or HCs?

BrianD3

That bordeline figure is the lambda reading. I doubt that any of those additives that you put into the tank will affect it much.

You may well have a slight blow in the exhaust which is causing this high lambda.

ciscokidder

Gents thanks for those replies. Saved me a foolish action there, cheers.

Marcus.Aurelius

I thought lambda was 1.003 not 1.3.

A lambda of 1.3 would mean your engine is dead!!!

BrianD3

Its 0.97-1.03, 1.003 is near perfect. Even though the OP said 1.3 I'm pretty sure he has left out a zero

Marcus.Aurelius

BrianD3 wrote:

Its 0.97-1.03, 1.003 is near perfect. Even though the OP said 1.3 I'm pretty sure he has left out a zero

You mean 1.000 is perfect, a perfect balanced proportion surely????

At any rate, the STP could still throw the lambda past the tolerance levels, as it is added to the fuel mix and so it may influence gas levels in the exhaust system.

zapata

Sorry about hijacking this thread.

Would an additive help out my situation?

1999, 1.6 petrol, black top engine, mondeo failed CO emissions.
Results

Engine/Oil Temperature 82 celcius

Low idle CO 0.05 vol%
(700 rpm) HC 0 ppm

High idle Lambda: 0.985
(3130 rpm) CO 0.38 vol% above 0.3 % fail
HC 120 ppm

ciscokidder

Yeah I did miss a 0 ....
Will be spending the day today finding out all about lambda ....

:)

ciscokidder

So - results are in . Pass.

Lambda was 1.00 in the nct test - so clearly something dodgy with caroll kinsella testing device (though car would haave been cold in CK and hot in NCT)


Thanks for the advice all.

MercMad

ciscokidder wrote:

So - results are in . Pass.

Lambda was 1.00 in the nct test - so clearly something dodgy with caroll kinsella testing device (though car would haave been cold in CK and hot in NCT)


Thanks for the advice all.

...........well thats your answer right there, colder engine = higher emissions !