Mechanics

MY CAR FAILED TO PASS SMOG I AM CONFUSED

1995 Geo Metro • 244 miles

I have a 1995 geo prism 1.6 that failed smog because of high hc and function insp for timing my question is why the timing failed it was recorded at 10 btdc and I checked it and it is 10 btdc which is the correct timing. So I am confused why it failed if timing was checked on number 1 cylinder, revered engine timing settle back just fine idle was ok car had high co reading on smog by still within passing. Hc failed at both rpm tested
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Kuruph
May 7, 2012.




When was the last tune up? Make sure oil is clean.

I changed the oil 4 month ago but am willing to do it before I resmog had the car looked at and they said all cylinders have good pressure and let me know that the upstream o2 sensor failed. I replaced the spark plug and wires a month ago but didn't replace the distributor cap. Belts look to be in good condition. I have no fault codes displayed. I also put fuel injector cleaner in a month before smog test. I think that covers all the maintenance/tune-up I did. But I am still confused as to whether I need to adjust the timing. 10 btdc is what I read and the smog tech but it still failed in that area. I am hoping it is just human error because 10 btdc is what I have in my car manual.

Tiny
Kuruph
May 7, 2012.
And also as I stated in the first question I also replaced both o2 sensors.
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Tiny
Kuruph
May 7, 2012.
A failed HC-could be caused by ignition misfire, lean misfire and low engine compression

Tiny
Rasmataz
May 7, 2012.

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