JasonGW Posted August 19, 2011 Report Share Posted August 19, 2011 I've got an old 210 I'd originally bought as a parts car but ended up loaned to a friend. It's only got 125,000 miles on it. 2 years ago I had the carb rebuilt (car had been in some old lady's garage for 16 years untouched after her hubby died, and the rubber was all rotted out) and it passed smog with flying colors. Now it won't. It's showing really high on HC's and on NO. This is a California car. I've made sure the timing is set dead on, leaned up the carb more than I thought I should, changed every filter, spark plug, wires, cap, rotor, and even filled the tank with premium plus octane booster, all to no avail. Those changes netted a 0.5 reduction in HC's and I didn't even notice how much in NO. Shop guy said maybe vacuum lines, but I can't find a leak anywhere and the engine idles smooth as butter, has good power and doesn't belch smoke. I asked if it could be the catalytic converter and he said "not very likely at all." Any advice would be deeply appreciated. Jason Quote Link to comment
ggzilla Posted August 19, 2011 Report Share Posted August 19, 2011 Leaning the mixture causes NOx to spike and HC to rise. Instead adjust the mixture to factory specifications. Make sure it is fully warm (15 minutes driving) before taking it to the test, run it at a fast idle (1500 RPM) for a minute before the test. Quote Link to comment
JasonGW Posted August 19, 2011 Author Report Share Posted August 19, 2011 Leaning the mixture causes NOx to spike and HC to rise. Instead adjust the mixture to factory specifications. Make sure it is fully warm (15 minutes driving) before taking it to the test, run it at a fast idle (1500 RPM) for a minute before the test. Interesting, so it may have been too lean the first time around, which would explain why there was no benefit after I leaned it up more. But here's what's odd: the gas mileage hasn't been great (25 or so, automatic), and the exhaust was a little damp and "gassy" smelling, which is why I thought it was probably too rich (well, and the smog tech said he felt it was too rich as well). Is there something else that might be? Quote Link to comment
ggzilla Posted August 19, 2011 Report Share Posted August 19, 2011 Yes, it might be anything: * Compression is getting marginal (worn rings) * Coil is going bad (slight misfire) * Vacuum hoses are misrouted, hooked up incorrectly * Electric wires are incorrectly connected * Emission control has stopped working * Air filter is clogged But the most likely cause is that it is not tuned to the factory specification. Quote Link to comment
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