1991 Honda Accord Failed CA Emission Test for High HC and High NO

1991 Honda Accord 4 cylinder 2.2L engine failed CA SMOG emission test.

Fails in the VIR:

Ignition timing: 22 BTDC (tech told me it should be 15)

HC PPM: 15mph 125 25mph 100

NO PPM: 15mph 1700 25mph 1384I

I'd like advice about what the likely cause(s) are for the high HCs and high NO emissions and what I can do to fix my car so it will pass CA SMOG test. Could those high levels both be caused just because the timing BTDC is too high? Are the EGR or ECT sensors possibly at fault? How can I figure this out without paying the large 'diagnostic' fees various repair stations are quoting me. I'm unemployed and disabled with no income so I can't afford to just pay a few hundred $$ to a mechanic to figure out and fix what I think is probably something simple I could do myself with the help of a friend. Any advice or information would be greatly appreciated so I can get my car to pass smog so I can start driving again to get to doctors appointments and to try to find a job. Thank you in advance. All other things listed on the VIR report have pass result except for 4 items that say N/A under 'result': EGR functional, thermostatic air cleaner, air injection, and fillpipe restricter.

Answer:

You will need to correct your Honda Accord's ignition timing and have the vehicle retested. The new results should then be diagnosed. HC will more than likely decrease once the timing is within specs. The NO however will probably increase, as retarded timing (which is the current case) typically lowers NO emissions.

Or assumption would be that the high HC is caused due to the overly retarded timing (22 BTDC) and the high NO is caused due to a defective or malfunctioning EGR system.

The EGR system recirculates exhaust gases back into the combustion chambers. This keeps combustion chamber temperatures down (because exhaust gas contains no or little fuel) and reduces NO emissions. The EGR valve should be inspected to ensure its proper operation. There are a few thing which may go wrong with the EGR system. It may be possible that the EGR valve is plugged with carbon deposits and is not opening properly causing a exhaust restriction, or there may be a problem with the vacuum system which is used to open and close the valve. Utilizing a hand vacuum pump (or a screwdriver) you can open the EGR valve manually while the engine is running and check for an RPM drop. This will at least ensure the EGR passages are open and you can then diagnose further. Be careful the engine will be hot.

Fix the timing and get a smog check retest. You can continue diagnosing after that if your 1991 Honda Accord still fails the smog inspection. Good luck.

posted by SmogTips Support