HC & CO emissions and fuelling
Discussion
Hi All
Just want a bit of a discussion to see if I understand it right. I had my engine on V8S looked over as part of a service and I mentioned to the garage to check timing, air flow meter output readings, fuel enrichment, timing (and advance) and emissions.
Timing was 6degs too retarded so was advanced but it came back that I had v low CO emissions at about 0.2% which is consistent with all the MOTs I have but was told with no CATs that its really really low and so is running v lean. They used adjustment on the AFM to enrichen so its now emitting CO at 1.7% at idle when hot.
What's weird is that I've been trying to deal with what was diagnosed as overfuelling for a while so totally baffled now.
But have to say the engine ran better than it has for ages and pulled really smooth and well on the way home.
anyone like to offer some sort of explanation for it? Anyone got any comparative figures for non CAT engines?
Could it be similar to something counter intuitive I've read like when there's an air leak it can cause more air to enter the engine so it starts lean but then the AFM reads lower and then can actually lead to more fuelling when trying to keep the idle revs?
Just want a bit of a discussion to see if I understand it right. I had my engine on V8S looked over as part of a service and I mentioned to the garage to check timing, air flow meter output readings, fuel enrichment, timing (and advance) and emissions.
Timing was 6degs too retarded so was advanced but it came back that I had v low CO emissions at about 0.2% which is consistent with all the MOTs I have but was told with no CATs that its really really low and so is running v lean. They used adjustment on the AFM to enrichen so its now emitting CO at 1.7% at idle when hot.
What's weird is that I've been trying to deal with what was diagnosed as overfuelling for a while so totally baffled now.
But have to say the engine ran better than it has for ages and pulled really smooth and well on the way home.
anyone like to offer some sort of explanation for it? Anyone got any comparative figures for non CAT engines?
Could it be similar to something counter intuitive I've read like when there's an air leak it can cause more air to enter the engine so it starts lean but then the AFM reads lower and then can actually lead to more fuelling when trying to keep the idle revs?
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