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Discussion Starter #1
Well lads. I bought a R33 Skyline 2.5turbo there about a month ago but havin problems getin it Nct'd cause of high emissions. The car is standard with cat back exhaust, frount mount intercooler, and mushroom air filter.
I put it true nct 3 times and it failed.

First time Emissions
Low idle CO 6.73 vol% (above 0.50% fail)
High idle CO 6.18 vol% (above 0.30% fail)
Lambda: 0.83 (not between 0.97 and 1.03 fail)
HC 198ppm

I then changed the cat, changed the lambda sensor with another second hand one, and mixed dipetane with fuel and gave it a good drive!!!

Second Nct time Emissions where:
Low idle CO 4.39 vol% (above 0.50% fail)
High idle CO 2.97 vol% (above 0.30% fail)
Lambda: 0.91 (not between 0.97 and 1.03 fail)
HC 205ppm (above 200ppm fail)

I then replaced the lambda sensor with a new universal one!!!

Third Nct time Emissions where:
Low idle CO 3.21 vol% (above 0.50% fail)
High idle CO 4.71 vol% (above 0.30% fail)
Lambda: 0.86 (not between 0.97 and 1.03 fail)
HC 223ppm (above 200ppm fail)

The nct man said the lambda sensor reading was constatly going up and down .

So anyone any idea what could be causing these high emissions? Could the ecu be f**ked?????

West Sussex Area Rep
4,952 Posts

Premium Member
2,723 Posts
I don't like to be the bearer of bad news, but I had exactly the same problem as you when I had my R33 and I tried everything to get it sorted but nothing worked.
In the end I found the problem when I went on a dyno run and only produced 165bhp. First thing I did after that was a compression test which found cylinder 5 had dead rings/ringlands. So all the fuel going in to cylinder 5 wasn't being burnt and gave me high CO readings. I never even considered this as an option since the car drove perfectly with no misfires, pops, bangs etc.

If I were you, I'd start with a compression test as it only takes 5 minutes and could save you a lot of messing around in the future.
If that all seems ok then I'd go with the water temp sensor as Ben suggested :bigthumb:

711 Posts
i would be inclined to put a engine flush through then new oil and filter.Its surprising what a difference it makes,and give the car a good thrashing just before the emissions test.

Germany East/Central Nord Rhein Westfalen
3,039 Posts
Water temp sensor oil and filter change check spark plugs check compression.
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