Silverti
11-17-2011, 02:01 AM
Hi guys,
Sorry about the long post, but i'm a bit stumped.
About 2 weeks ago i noticed that i wasn't getting the usual 300 miles or so to a tank. It had dropped right down to 220. This gives me around 23-25 mpg instead of the usual 30-35.
Thought it may have been a fual leak, so checked the tank and pipes but all was sound.
Went and had the codes read and it said the pre-cat o2 was knackered. Duly replaced sensor and took on a 150 mile run, worked out mpg and still down at 23. Back to garage, no codes present. Stuck her on an emissions test and the readings were sky high.
CO was 8% (max allowed is 0.2%)
hydrocarbons were 1000 (max is 200)
lambda was around 0.8 (should be 0.9 - 1.0)
The engine is running extremely rich, the hydrocarbons reading shows that there is an excess of unburnt fuel coming through the exhaust. The Cat is most likely dead from the excessive rich running but i can't see it making the emissions go as high as they are, and i'm reluctant to change it until i find the cause of the problem, otherwise i might kill a new cat.
Driving round today, pretty cold outside and the engine wasn't getting right upto temperature until i was in traffic so i think the thermostat needs changing but the emissions seem so high that this couldn't be the only problem.
Or i guess it could be a mixture of the thermostat, lambda and cat all at the same time...
Any ideas?
Cheers
Rob
Sorry about the long post, but i'm a bit stumped.
About 2 weeks ago i noticed that i wasn't getting the usual 300 miles or so to a tank. It had dropped right down to 220. This gives me around 23-25 mpg instead of the usual 30-35.
Thought it may have been a fual leak, so checked the tank and pipes but all was sound.
Went and had the codes read and it said the pre-cat o2 was knackered. Duly replaced sensor and took on a 150 mile run, worked out mpg and still down at 23. Back to garage, no codes present. Stuck her on an emissions test and the readings were sky high.
CO was 8% (max allowed is 0.2%)
hydrocarbons were 1000 (max is 200)
lambda was around 0.8 (should be 0.9 - 1.0)
The engine is running extremely rich, the hydrocarbons reading shows that there is an excess of unburnt fuel coming through the exhaust. The Cat is most likely dead from the excessive rich running but i can't see it making the emissions go as high as they are, and i'm reluctant to change it until i find the cause of the problem, otherwise i might kill a new cat.
Driving round today, pretty cold outside and the engine wasn't getting right upto temperature until i was in traffic so i think the thermostat needs changing but the emissions seem so high that this couldn't be the only problem.
Or i guess it could be a mixture of the thermostat, lambda and cat all at the same time...
Any ideas?
Cheers
Rob