The ac shouldn't really matter.....it would bump up the idle a bit?

Does your car have an EGR system? I know you are not in the US so that is why I'm asking.

 

my engine don't have EGR system.

 

You had high CO, but what about HC (hydrocarbon)? I doubt you have oxygenated gas in UAE, but why would you add alcohol? This will require an apparent leaner A/F ratio because of the oxygen in the alcohol. One liter may not be much, but it depends on how much gas was in the tank when you added it. It might take a while for the ECU to adjust to the fuel. How much ahead of time did you add the alcohol?

In my state, when I take the test, the test station recommends that all accessories are OFF (A/C, lights, etc.). Also, they tell you not to turn off the engine prior to the test.

 

Oops, I meant richer above. If everything stayed the same but you added alcohol, the engine would run leaner because alcohol has oxygen in it. So, to keep the A/F ratio correct with alcohol in the fuel, more fuel would need to be injected for a given amount of air compared to non-oxygenated fuel.

 

she passed the test

new spark plug
half liter of denature alcohol on half tank
remove the stock air filter - and put it back after the test.
hway run for 30 mins on the way to testing center

thanks for all your advise

thank you for the advise

 

i have a 93 acc lx and it failed twice bad CO. new upgraded plugs, air filter, oil change, fuel stable and premium gas. dont know wut else? someone says i need a maf sensor or O2 sensor, but oriellys says that model and year doesnt use it? new to hondas wth

 

Your car has an O2 sensor but it doesn't have a MAF sensor.

What "upgraded" plugs?

Fuel stabilizer is for long-term storage; I don't know what it would do for emmissions?

Has you checked the spark timing? Try injector cleaner (not the same as stabiliizer)?