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Took the s4 for mot today. Bought it last year and only getting it to mot now. Has been parked since 2008. Failed on emissions. CO at idle was 1.990 and HC was 3380. The engine is an AAN with an MTM chip, rs2 exhaust manifold, a stainless steel exhaust without cats and a k&n panel filter in the air box. Where do I start looking to get the numbers down.
From memory, without a cat, you should be down around 0.75% CO. SO you're miles off! 3880 HC is pretty terrible too, you'd expect less than 500 on a car running properly.
Pull the codes and see what's up. Sounds like it might be in warmup mode or running the wrong injectors maybe...
Cheers'en, AndyC
1994 ABY Coupe - Projekt Alpinweiss
Took the s4 for mot today. Bought it last year and only getting it to mot now. Has been parked since 2008. Failed on emissions. CO at idle was 1.990 and HC was 3380. The engine is an AAN with an MTM chip, rs2 exhaust manifold, a stainless steel exhaust without cats and a k&n panel filter in the air box. Where do I start looking to get the numbers down.
Here kitty, kitty. Nice kitty.
That and new plugs and air filter, fresh fuel and an oil change.
Then only go for your MOT test if the car has been run hard and the coolant temps are up.
On a related note before any of the above, you might want to check or replace your G62 ECU coolant temp sender (if bad it will cause the ECU to run the engine rich which would result in at least higher hydrocarbons (especially with no cats) and possibly higher carbon monoxide as well).
CO is no problem as due to age and test limits it is allowed to run up to 3.5% vol or less. 1.990 is high though. I am also allowed 1200ppm so i need to get the numbers down from 3380. I have a 20v ur quattro with an rr engine and no cats and it runs at 0.5% vol. The HC is he problem.
Last edited by chiefmechanic; 19 September 2013, 21:59.
That's not going to help, he's got no cats to warm up.
John
We have an old diesel VW LT van which only does a few trips to the beach every year, it will not pass emissions unless you thrash it about 5 miles down the dual carriageway and back then drive it straight into the test station while it's still hot.
We have an old diesel VW LT van which only does a few trips to the beach every year, it will not pass emissions unless you thrash it about 5 miles down the dual carriageway and back then drive it straight into the test station while it's still hot.
Any idea which spark plugs I should use. Will the standard plug work well with a lightly modified engine. I tend to drive sedately with a minor thrash now and then.
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oil changed and air filter checked. K&n panel filter in the air box fitted
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