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car failed mot on lambda reading, was 1.12 first test, then 1.05 second time....

what will the cause be,...its a fresh import, and tester didnt fail ex system, but issued advisory due to cat noisy,..but no holes...

could it be simply that the car is running too rich..?

and if so, how do i adjust it...



btw, new cat coming as it needs replacing anyhow, just want to make sure it passes...


carl
 

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are those lambda readings the same as the voltages that the stock "titanium lambdas" put out? Mine read 1.6v and 1.1v respectively.

Does a higher voltage mean richer or leaner btw?
 

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The lambda values are not voltages. The lambda value is derived from the stoichiometric air fuel ratio of 14.7.

lambda = 1 AFR = 14.7
lambda > 1 AFR's > 14.7 i.e. lean
lambda < 1 AFR's are < 14.7 i.e. rich.
 

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could it be simply that the car is running too rich..?
That's why mine failed the lambda test on it's first MOT....


Well, the first after I bought it anyway. How the dealer got it through is beyond me, but that's a different story altogether :D
 

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What lambas are needed to replace them in the GTR? Are they titania or zirconia type? Are they 2 heater wires and 1 sensor wire?

My car is running very rich and i think that the lamba's may need replaceing as they are service items anyway.
 

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Mine were just direct from Nissan - can't remember exactly what type they were.
 

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if you want it to pass an MOT, try sticking the the emission testers up some other buggers exhaust when the mechanic isnt looking :chuckle: :chuckle: :chuckle:

only joking mods. ;-)
 

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An out of scape lambda reading does not mean your lambda sensor is no good, It could be any number of things but if the cat is noisy but not blowing it might have been gutted.
 

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Try borrowing someone else's cat?

Very hard to adjust fuelling on a stock car.
Is your air filters clean?
Is your water temp sensor working correctly?


Sorry to have hi jacked your post earlier!!
 

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Just because the lambda reading is lean does not mean that the engine is running lean. It is common for a hole in the exhaust or damaged gasket to allow extra air into the exhaust and this is what the mot tester is reading giving a high lambda value. Could also be caused by a damaged cat. If the lambda sensors aren't working it would be more likely to run very rich, i.e. lambda < 0.8.
 

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are those lambda readings the same as the voltages that the stock "titanium lambdas" put out? Mine read 1.6v and 1.1v respectively.

Does a higher voltage mean richer or leaner btw?
Higher voltage usually means richer. But the voltage should flip-flop as the sensor generates its own voltage. When the sensor reads a rich mixture, the computer then leans out the mixture.

When thee sensor reads a lean mixture, the computer then makes the mixture rich.

This happens in about 50 - 100 milliseconds.
 
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