Do you have a distributor on it, or is it electronic. If it's a distributor,
check the cap. If the points on it are worn or corroded, that may be it. My
dad had the same problem on his Honda, the HC's failed. He gave it a tune-up,
replaced the spark plug wires and replaced the distributor cap, and it passed.
If it's the electronic ignition, it may be faulty. I'm no expert, but I think
if the spark is bad or not a full spark, then it doesn't completely combust.
That may be why you're getting high CO, CO2 and even O2 numbers. Hope this
Thanks for the advice, tweliver. This vehicle has a distributor, but no
points - it's electronic ignition, with a Hall sensor pickup and the the
infamous TFI module controller. I will scope the ignition - the computer in
this car is not smart enough to self-diagnose a misfiring cylinder, though
I would expect an elevated CO in such case, uneven idle or driveability
My question was whether anybody can point me to something which causes
elevated HC, but does not cause an increase in CO.
I am NOT getting HIGH CO - on the contrary - it's practically zero. As for
CO2 and O2 - I think that the higher the merrier. High CO2 shows that the
exhaust is coming out of the tailpipe, and does not go anywhere else. High
O2 (though I am not sure that mine qualifies for high - there is no limit)
most likely just indicates that the thermactor (air pump) is doing its
Warm the car up up, change the oil, then drive it at highway speeds for 30
minutes.. take it back to the test and I bet you find the results are a lot
Ever look down the throat of a TBI at cold idle? The gas just dribbles out
of the injectors..
Seems to me, that's been a "Hot Tip" for passing the E Chack for some
years... and yep, if the oil gets a fair amount of raw gas repeatedly and is
driven for primarily short trips, to boot, it certainly wont help.
Blowby, and valve seal problems can contribute.
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