Technical emissions failed

[Pullu]

Hello everyone,

I Have a 1992 uno with a 999cc fire engine and a carb. This morning I went to did the vehicle road test and only failed the emissions test.

Theres are the results:

CO : 4.51%
CO2: 11.70%
HC: 659ppm
02 Rel.: 10.90%
Lambda: 0.898
RPM: 882 min-1

Anyone could please help me identify the problem?

 

[dave]

Lambda: 0.898, i didnt think you had a Lambda

 

[Pullu]

That's what I thought too I don't know why it was in the result sheet.

Btw update i removed the spark plugs and this is their condition

 

[Hyperspace]

looks like the carb needs a bit of a tune, that one cylinder is running very hot (lean). Possibly the valves need a good look over too although it could be something as simple as glowing deposits, as the other three cylinders don't look too bad, 2 are slightly rich. Does that model have a cat? That hot cylinder will eat your cat.

It may also be a vacuum leak, you can spray some carb cleaner around the manifolds where it meets the head, and also around the carb, while the car is running, listen for a change in idle that corresponds with spraying on any specific spot.

 

[Pullu]

My model doesn't have a cat. I will try and check for leaks tomorrow although there shouldn't be any.

Fuel economy which i think is related to the emissions is also bad I'm getting less than 80 miles on 13 litres of fuel

 

[Hyperspace]

I think whoever tuned it, had to set it up rich to make up for that one lean cylinder. Just tuning the carb to bring the feul mixture down, would probably make it run badly and will increase chances of complications of makeing the lean one even leaner. (lean is bad, can burn pistons even) If you don't find a leak, the head will have to be checked.

 

[bedofercni]

+1 For leaking... Check the seals at the inlet manifold. You should buy a carb overhoul kit, with jets and seals. When I take my Uno to the MOT the CO was too high. It turned out the main jet was sized 135 instead of 80. (Weber ICEV 32). A carb overhoul kit solved the problem. Clean the carb, use the overhoul kit, check the inlet manifold seal and after that set the carb.

Btw every car has a lambda...Its a stoichiometric number. If its nearest to 1 its the best... If the lambda is 1 the burning is the most efficient... This is why the injector better than carbs... The sensor keep the burning lambda near 1 in every condition...

 

[Pullu]

I Checked the carb and it is flooding which should be a float problem right? How do i measure the float level and what level should it be set? carb is weber 32 tlf 4

 

[bedofercni]

I Checked the carb and it is flooding which should be a float problem right? How do i measure the float level and what level should it be set? carb is weber 32 tlf 4

I was hoping a book for my birthday wich has all the webers and solexes data organized by car types. Unfortunately someone bought it before my girlfriend... I will check the haynes manual after i arrived home...