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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
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Monday, May 7th, 2012 AT 2:10 AM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,747 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
  • 47,640 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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