Denatured Alcohol?
 

I have failed smog 5x's after a ton of repairs- I'm Desperate.

Will this lower NOx?

How should I do it?

I have a '96 Civic DX.

By the way, I'm a little over on NOx at 15mph.

Will what lower it?
And do what?

Denatured Alcohol.

I've heard even Heet will?

Have you tried injecting more fuel?
because high NOx is indicative of high combustion temperature. or so i was told.
or try retarding your ignition timing 4 degrees down.?

If combined with HC and CO levels well under the limit, high NOx generally means the engine is running too lean. High on all 3, probably the catalytic converter is worn out.

If you want to try some alcohol in the tank just use E85 (sold at gas stations, 85% ethanol and 15% gasoline, works in "flex fuel" cars) if available in your area. It is much cheaper than anything else. Heet is basically alcohol, though it may be methyl or isopropyl instead of ethyl. Ethyl alcohol is the base for E85 and denatured alcohol.

I have no idea though if alcohol will reduce NOx emission. Use too much and your car will run very badly. Nearly all the gasoline sold now starts at 8 or 10% ethanol so you need to blend in at least that much to change anything (i.e. one bottle of Heet in a gallon of gas isn't a significant amount.)