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
When was the last tune up? Make sure oil is clean.
May, 7, 2012 AT 3:49 AM
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.
May, 7, 2012 AT 3:50 AM
And also as I stated in the first question I also replaced both o2 sensors.
May, 7, 2012 AT 7:59 AM
A failed HC-could be caused by ignition misfire, lean misfire and low engine compression