My car failed to pass smog I am confused

Tiny
KURUPH
  • MEMBER
  • 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
Monday, May 7th, 2012 AT 2:10 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
When was the last tune up? Make sure oil is clean.
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Monday, May 7th, 2012 AT 2:12 AM
Tiny
KURUPH
  • MEMBER
  • 3 POSTS
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.
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Monday, May 7th, 2012 AT 3:49 AM
Tiny
KURUPH
  • MEMBER
  • 3 POSTS
And also as I stated in the first question I also replaced both o2 sensors.
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Monday, May 7th, 2012 AT 3:50 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
A failed HC-could be caused by ignition misfire, lean misfire and low engine compression
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Monday, May 7th, 2012 AT 7:59 AM
Tiny
KIP#1
  • MEMBER
  • 3 POSTS
I have the exact same problem with 91 nissan, I believe a cap and rotor will solve the co problem--but the defective timing makes no sense----its at 10 BTDC and it runs great-no timing noise.
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Wednesday, July 20th, 2016 AT 4:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
Hi,

It sounds like the catalytic converter is weak and needs replacement. Here is a guide that will help you.

https://www.2carpros.com/articles/catalytic-converter-replacement

Let us know what you find out

Best, Ken
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Thursday, July 21st, 2016 AT 9:32 AM

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