MY CAR FAILED TO PASS SMOG I AM CONFUSED

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

6 Replies

  • Tiny
  • Jacobandnickolas
  • EXPERT
  • 68,402 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

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

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
  • MEMBER

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

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
  • 2CarPros Ken
  • ADMIN
  • 4,187 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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