94AccordEXWgn_5

I posted this to the "introduce yourself" thread but I figured it's better here.

My 94 Accord EX Wagon (5-spd manual, 214K mi) failed CA smog emissions test for high HC @ 15 mph (69 ppm measured; 61 ppm max) and barely passed 25 mph HC (right at the limit - 36 ppm) and 15 mph CO (right at the limit - 0.51%). See test results below.





Prior to the smog test, I had my local independent Honda shop inspect the EGR ports and check the other EGR related bits. They ports were gunked up and the shop cleaned them out. A bit of background, my car failed smog in 2011 and the diagnostic shop recommended a catalytic converter replacement and the car passed with flying colors. In 2013, the car failed w/ high HC at 15 mph and the EGR port clean out solved that problem and it passed the re-test.

Following the recent test fail, I replaced the plugs - NGK (even though they were only 6 months old and had 2,500 mi on them), wires - NGK; rotor, and cap thinking it was an ignition issue, I replaced the O2 sensor - Denso (existing sensor was three years old) for good measure since the CO was close to failing. The re-test results were worse. The car failed at 15 mph HC (112 ppm), 25 mph HC (39 ppm) and 15 mph CO (0.75%). See results below.





Any suggestions on what to do next to get it to pass? I've read a few threads but the diagnosis seem to run the gamut from engine running lean or rich, exhaust leak, gasket leak, loss of compression, vacuum leak, etc. I was so close the initial test (+8 ppm HC) and now worse off after the changes. Any help would be greatly appreciated. Thanks in advance.

Ryan
1994 Honda Accord EX Wagon (5-speed)

MAD_MIKE

Verify a few things
Fuel Pressure. If it is too high it will cause a rich running condition leading to high CO.
Leaking fuel injectors. If they are dribbling they will cause excessive fuel issues.
FPR is not damaged.
EVAP system is functioning correctly. A fuel soaked charcoal cannister will cause a fail.
Excessive fuel contaminated oil. Always change oil before a smog test just to be certain.
Faulty PCV system. If the PCV valve or hose is gummed up it cannot properly remove excessive HCs in the crankcase. PCV valve should rattle when shook, clean it out with Carb/TB cleaner, verify the hose and port on the intake are free and clear of any carbon/sludge buildup.
Closed loop issues. Faulty senors (IAT, Thermo-sensor, stuck Thermostat, faulty O2 readings(leaking gaskets or wiring issues)) can cause a false air signal, artificially causing higher fuel consumption.
Check MAP/TPS/etc sensor readings.
Air filter should be clean/clear. It should pass the light test.

94AccordEXWgn_5

Thanks for the tips. I checked the PCV valve and I can hear it rattle but it is faint (how evident should the rattle be?) so I'll plan to clean it out before the re-test. I also plan to change the oil (it is about 5 months old but only 2,500 mi) and will check out the evap canister. The air filter is clean.

Any chance that the ignition timing is to blame?

MAD_MIKE

PCV on Hondas is plastic so it will not rattle/clink like a metal unit, but you want it to be able to move and see the spring function.
Spray some cleaner inside it to verify it is not gummed up or has a blockage, same with the vacuum feed from the intake manifold. Pull the hose off and verify the port/hose is gunk free. Same with the fresh air feed attached to the intake tube to the valve cover.