What is the effects of smogging a car without the thermostat?
The reason I ask is that I failed Smog on my civic vx - NOx was too high.

High Nox means your EGR system is plugged up and/or combustion temps too high.
I replaced my intake with one that I know the EGR passages are not clogged.
Before I test my car, I thought about running my car with no thermostat.

On my last smog test that I failed, I passed HC at a very low 9PPM and CO at less than 1% (I think it was %0.09). I failed with NOx at 1600 or so...
I think if I ran without a thermo these measured values wouldn't change much.
Perhaps (and I'm hoping) Nox would be lowered.

Gary

 

i had that problem before. the smog guy told me just to fill up my tank with premium, finish the tank, fill it up again... run on the freeway before u get to the smog station. make sure everything is hot cause ur car without a thermostat will cool faster which makes the ecu run it richer (like when u start the car in the am).

 

I just saw some of your replies to your Nox issue.. why would premium cause nox to go down?

 

I'm thinking about throwing some techroline in there... might clear up some carbon as well....

It kinda sucks, it's hot out here in CA and I need to smog it soon.. I don't want to smog it when it's hot... perhaps I need to get to the smog station at 7am...

Gary

 

higher octane equals better... more complete combustion. also, gas with more alcohol like ethanol/methanol is more volatile. nox is from unburnt fuel. oh, all addatives are the same. they dont work. its all avgas, which is bad foe oxygen sensors

 

FYI:
Hc is unburnt gas.
Nox is from high combustion temps

 

then it should break down in the cat.

 

just dump a bunch of denatured alcohol in the tank. If you are close to the limit it will pass for sure.

 

I heard about that, but doesn't that just lower HC?
it's also bad for your fuel lines and all the rubber components.
Gary

 

Whooho, I passed smog today!

Prev tests:

MPH HC CO NO
15 9 .02 1826
25 8 .02 1635

Today's test

MPH HC CO NO
15 38 .09 185
25 19 .05 178

I cut my NO by 10 folds!!!

So, how did I do it?
Of order of importance, I think:

1. timing from 16 to 13 deg
2. clean EGR passageway by replacing intake with a known good one (I would put that as #1 but my intake was not completely clogged when I tested it)
3. cleaned carbon from intake ports on the engine and new intake (esp near the injectors)
4. new plugs - one step colder gapped at .041-.043; original one was probably 5 years old and had a gap of .60-.70 when taken out
5. New air filter (probably did nothing - I should have kept the old one in since old dirty filter will increase HC (which is what I want).
6. Cleaned EAVC (screen plugged) - not sure if this can affect NO

I went in early before temps hit 100 deg. Last time I warmed up the car for 30 minutes driving it on the highway. Not this time. I drove it to the test only station 5 mins away turned it off and waited. Engine cold when the guy arrived. This should be #3.5.

My goal was to richen up the mixture somehow. I think retarding the timing helped, but not sure how it affects gas mileage. Since it's a commuter, I will probably advance it back to stock or higher.

Anyways, this smog saga has come to a close for me. I spend so much time on it that I was getting frustrated and was wondering if it was worth it. Since I commute about 120 miles/day, I can say it was worth it.

Gary


Modified by garyhgaryh at 5:45 PM 9/3/2007


Modified by garyhgaryh at 11:57 PM 9/4/2007