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High Hydro Carbons


In Third Gear

Took my s3 petrol for an mot and its failed the emmissions test on high hydro carbons the garage adjusted the carb but couldn't get them below 1489 pass rate is 1200ppm. I have done everything I can think of new air filter, carb gasket's exhaust gaskets, vacum hose's oil change ect but no difference. Iam fairly new to all this only had the landy a couple of months.
Can anyone help. Cheers Rudi:)
What age is your Series 3?

Don't use a single choke Weber though. They are absolutely horrible on a 2.25 Litre Petrol.
Check the points gap and make sure the timing isn't retarded. If you have old, carbon type plug leads, change those and the plugs.

If not, then new jets or a carb, as CCK syas.

After 1st August 1975 it is an Analyzer Test for Idling emissions, before that is visual. From 1st August 1992 is a BET Test and Cat Test.

If your NT only did a visual, he was wrong and you have a Void Test.

Just for the test run her a little lean. Run a bit of Redex through the system, Check the ignition timing and the gaps as per above. ^^

IMHO don't use a weber as they are the spawn of lucifer.
Checked the gaps and timing. Going back in tomorrow!
As for the weber carb, to late new one arrived yesterday and just fitted it:( .
Thought they were the BEST.
Webers are good carbs. They tend to ice up a bit in cold weather,on the Land Rover,as the venturi is a bit too small and the amount of air rushing through overcools the carb body. Draw warm air from the exhaust manifold and it will be OK.

If you've got an HC reading as high as 1400-odd, I'd say you've got a proper ignition fault or else you've a burnt valve seat. The 2 1/4 petrol engine is easy to get through the emissions test if it's running correctly and hasn't got any faults.
For example, the last time I put a S3 through the MOT, the CO at idle was around 1% and the HC reading was IIRC 294ppm against the limit of 1200. When the CO was richened to about 2.5% the HC readings dropped below 200ppm. This engine was just taken "as is", not Redexed or serviced specially, but is a known good low mileage unit that has always had frequent oil changes. Carb was a gutless wonder Weber 34ICH, BTW. Zenith tends to be a little bit higher on idling emissions than the Weber, but will still easily pass the test if in good order.
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