Originally posted by cawong11:
Those are some seriously high numbers. I think from previous discussions on this topic, high HC's are due to a lean A/F ratio, but I could be wrong.
I should have noted that the numbers are at curb idle. She was fine during the other portions of the test.
Both numbers would seem to indicate combusion inefficiency. High hydrocarbons usually indicate some gas getting through, which might indicate plugs and wires, or O2 sensors. I lean towards it being the latter. It could also be the cat, in which case, here comes the mystery mod!
I'll probably end up getting it looked at by a pro instead of throwing parts at it.
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97 BMW 540I Sport, six speed
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