phaser

I have a 1995 Honda Civic DX Coupe that failed its last emissions test due to high CO levels. (2.62 vs. 0.94 allowed @ 25/25 and 2.65 vs. 0.97 allowed @ 50/15). The check engine light is not on. I have owned the car for almost 15 years and it's the first time to fail the yearly test. I don't drive it very much and the fuel in the tank was rather old. I probably haven't driven the car 100 miles in the last year, and maybe 500 miles in the last 5 years.

So, I used up most of the old gas, then ran Red Line through the brake booster hose, and put the rest in the gas tank with fresh fuel. The air filter wasn't bad, but I replaced it anyway. I'm about to get an oil/filter change (last one was 3 years ago). And I'm thinking about replacing the spark plugs, and possibly the wires. I replaced the O2 sensor about 13 years ago.

Incidentally, the HC ppm numbers passed, but are a good bit higher than previous tests (124 vs. 167 allowed 25/25 and 142 vs. 173 allowed 50/15). And RPM is at 2719 vs. 3000 25/25 and 2029 vs. 3000 50/15.

The air pressure was down 7psi in each front tire for the last test, which has been corrected. I will drive the car for another week with the fresh fuel/Red Line mixture. Unlike before the last test, I'll drive on the interstate for at least 30 minutes and then take it directly for the new test. Any thoughts? Thanks!

mac25

What did the code say? Maybe your cat. died?

phaser

The check engine light is not on. I checked for codes and there are none. I certainly hope it's not the cat!

The testing facility gave me a sheet that says 'Failure for excessive CO' - Possible causes include: Faulty oxygen sensor(s); Faulty mass air flow sensor; Faulty PCV valve; Clogged air filter; Incorrect ignition timing; Faulty fuel pressure; Dirty fuel injection/carburetor.

mac25

Pull sensors and soak them in carb cleaner,

same with pcv or replace

disconnect MAF and spray it with some carb. cleaner, and don't touch it with your hands after, because you may get grease back on it.

check air filter



I don't think your timing would just change all of the sudden, have you serviced anything timing related since the last emissions check?

Also change the fuel filter, it can cause blocked flow and carbon to flow into your injectors.