My 1987 Honda Accord LX-i sedan (fuel-injected) failed smog today, after previously passing it with no problem in 2018. Everything looked good except for CO at 25mph. Never had this problem before, the car has been running fine for the most part. Mechanic suggested the fuel injectors may need adjustment, or some related parts (which he did not specify) might need replacing. From my research, high CO means the engine is running rich.
The fact that it only occurs at high speeds is puzzling to me, and the mechanic did not seem to know why either. I did some searching around and found that it could be: Coolant temperature sensor (I believe there are multiple on this car, I replaced a faulty one back in May 2018); O2 sensor; MAP sensor; leaky fuel injectors; clogged air filter (replaced only a few months ago); defective thermostat/thermostat stuck open; charcoal canister. PGM-FI light is not on, so nothing obvious. Only other item of interest is that I noticed several months ago that the radiator cooling fan sometimes immediately comes on at full blast during a cold start (usually at night or early in the morning), but not always. Keeps the temp needle lower than usual when it does occur. Eventually fixes itself after 20-30 minutes of driving.
- This topic was modified 10 months, 1 week ago by Reginald.
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