I recently failed smog in SoCal for the 2nd time. 95 GSR completely stock with freshly rebuilt motor (600 miles) and CARB legal bolt ons. I passed 2 years ago with same cat, O2 sensor, plug wires, etc. BUT had another freshly rebuilt motor with only 500 miles on it at the time @ 14 btdc and a slightly higher O2% reading. Heres my current situation;


1st Test (@ 15 btdc) 15 mph - 25 mph:

CO2/ 13.6 - 13.7
O2/ 0.0 - 0.0
HC/ 220 - 174 (max 90 - 56) Fail
CO/ 1.78 - 1.67 (max .54 - .53) Fail
NO/ 90 - 91 (max 711 - 754) Pass


2nd Test (@16 btdc) 15 mph - 25 mph:

CO2/ 13.7 - 13.8
O2/ 0.0 - 0.0
HC/ 224 - 157 (max 90 - 56) Fail
CO/ 1.66 - 1.51 (max .54 - .53) Fail
NO/ 215 - 210 (max 711 - 754) Pass


Does anyone have any advice for me as to how to lower HC and CO levels? Does the O2% reading of 0.0 mean I have a bad O2 sensor? Anything I can do other than spend hundreds on a new cat and O2 sensor? (fuel additives, etc.) Car runs perfect, no smoking, no knocking, or weird odors. I just need to pass smog, then motor is getting pulled out so I dont wanna throw too much $$$ at it.

 

Your CO is fairly high which would indicate that your fuel mixture is rich. The slightly high HC also may be a byproduct of an excessively rich mixture. However, if your catalytic converter is not working efficiently enough it could cause those readings too. You need to check cat temps with an infrared pyrometer first. The inlet side should be at least 100 degrees cooler than the outlet side. If the cat passes I would pursue anything that could cause a rich mixture like high fuel pressure or an open coolant temp sensor (which should throw a code).

The O2 reading doesn't have anything to do with you O2 sensor. I don't think retarding your timing would help much. The high CO reading won't change much if you retarded the timing.

 

UPDATE/RESOLUTION: I lifted the car to check the cat (looked ok) and the O2 sensor was kinda black (running rich). I noticed one of the wires was depinned. Dont have a clue how it got loose, but I put it back, started the car, and warmed it up. Drove over to the smog test and this time it passed with excellent results. Thanks for your input Scott Tucker. Just for ***** and gigs, my results were:


3rd Test (@ 15 btdc) 15 mph - 25 mph:

CO2/ 14.6 - 14.4
O2/ 0.1 - 0.1
HC/ 19 - 17 (max 90 - 56)
CO/ .09 - .16 (max .54 - .53)
NO/ 46 - 52 (max 711 - 754)