Trying to get my truck to pass smog in california

[sithways]

I have a 93 Ford Ranger 4 cylinder with a 2.3 liter engine. Two years ago (I know it was two years haha) I passed with flying colors. This year I took my truck in to for the test and the guy stuck the thing the tail pipe to see what kind of emissions it was kicking out before running the test. The numbers on CO2 were so high he said that I had a good chance of testing as a 'gross polluter'. Which is really bad news.

The only suggestion he had for fixing it was to start with the smallest stuff and work my way up the biggest which he said was a new catalytic convertor. He suggested that I start with changing out my plugs, wires and coil considering I have not in 6 years. I also had a new head gasket put in a month ago. Changed out (I have no clue what causes emissions to be good or bad, I am just letting you guys know what things have been changed recently) the water pump and radiator with in the last year. Changed the air filter and changed the oil a month ago. Starter is fairly new.

One side note. The guy who changed out my head gasket informed me that when trucks like mine get a lot older the thermostats become a problem and some times open or something at the wrong time and can crack the head. He said that since I was in California to just leave it out. So I have no thermostat. I am also running water through my system instead of coolant. Don't know if any of this stuff helps you guys. I just wanted to put as much info out there as possible.

Thank you in advance!!! Happy New Year!!

 

[adsm08]

Well first off, it isn't really a great idea to run around without a thermostat. Put that back in.

Second, CO2 s a normal tail pipe emission. The only two things that really should be in the exhaust gas on a vehicle with a cat are CO2 and water. Are you sure it wasn't the CO number that was high?

Third, there is in fact a sure-fire way to fix this correctly on the first try. GTFO of California. Move as far away as possible from that horrid place and you will be in good shape. Although I am told just jumping over into Arizona or Nevada, or really any other state is good enough.

Now on to the technical side of things.

There are a few key things that effect the tail pipe emissions, so lets get into a little bit of 5-gas theory. You have temperature, amount of fuel/air, the quality of the spark, and the health of the cat.

So when you burn fuel in an engine you throw air (O2) and fuel (HC (hydrocarbons)) into the cylinder and add a spark. The combustion usually results carbonmonoxide (CO) and oxides of nitrogen (NoX). NoX is only made above 1500, but that is combustion temp, not engine temp. Depending on the accuracy of the mix ratio and the quality of the spark there will either be some extra HC or O2 left over as well. So out the exhaust valve you are pushing CO, NoX, HC and O2. The cat is supposed to take those four gasses and jumble them up a bit. It catalyses a reaction to change the poisonous chemicals into not poisonous ones (hence the name catalytic converter). It absorbs molecular oxygen, and breaks it off the nitrogen atoms in NoX and then takes the CO and HC and rearranges those molecules with the oxygen atoms it has stored and makes carbon dioxide (CO2, not an environmental pollutant, despite what the communists in California would have you believe) and water (H2O).

If you are getting excessive CO2 then something is really wrong, and most of the problem is with the test and it's pass/fail point. Really the only way I can think of to have too much of an intended final product is to start with too much raw material, so idling too high for the test parameters. I am betting that your real failure was CO, in which case a tune up would be a good place to start if it hasn't been done in a while, but a cat may be the ultimate issue. Generally though high CO levels are due to a rich mix, so tune up, and clean all your intake related sensors, maybe put in a new oxygen sensor. It would be nice to know where the NoX number was, since that is what the cat is really intended to get rid of. CO is poisonous but breaks down quickly in open air, with little lasting effects. NoX is highly poisonous by itself, but IIRC when exposed to sunlight can break down into ozone (O3, where as the molecular oxygen we breath is O2) which in addition to also being bad for humans is not good for the environment either. This is also not to be confused with upper atmosphere ozone. When high up in the atmosphere ozone is a good thing because it helps reflect certain harmful types of solar radiation. Ground-level ozone never gets that high, since it is a fairly heavy molecule. What it does do is cause respiratory issues.


Was any of that helpful?


Also, check out this guy, he has some good stuff on the linked page, and one of the things he lists for high CO levels is a stuck open thermostat.

http://www.auto-repair-help.com/auto_diagnostics/diagnose_emission_test_failure.php

 

[sithways]

Honestly it could have been CO. He did not speak the best English. But it was either CO or CO2 that is for sure. What does it mean if I have too much CO?

By the way thanks for your answer. You mentioned temp and spark. So would you suggest starting with putting the thermostat back in and changing the plugs, wires, and coil considering I have not change any of that out in 6 years?

 

[sithways]

Also, do you think the fact that I am running water instead of coolant has anything to do with it?

 

[alwaysFlOoReD]

Honestly it could have been CO. He did not speak the best English. But it was either CO or CO2 that is for sure. What does it mean if I have too much CO?

By the way thanks for your answer. You mentioned temp and spark. So would you suggest starting with putting the thermostat back in and changing the plugs, wires, and coil considering I have not change any of that out in 6 years?

Yes, it's time to change plugs and wires and put a thermostat back in.

Also, do you think the fact that I am running water instead of coolant has anything to do with it?

Water is not good for the long term, but should be fine for now.

 

[adsm08]

Yes, do a tune up since it sounds like it has been a while, but I think the thermostat is probably the biggest issue.

 

[gw33gp]

I know this doesn't help the OP pass the test but if you have a 98 or later vehicle with the OBD2 port, it is pretty easy to pass the smog test in CA. They just plug into the OBD2 port and check everything from there. They also do a visual inspection to make sure all the smog related items are there. So, all you have do before going in is check for codes thrown and stored. If it has none and you have not removed any smog equipment, you should pass.

It has been that way for my last two inspections.

This year, I had to replace the DPFE sensor before I went in for smog check but I think that is related to NOX.

 

[RonD]

Yes, thermostat is a big deal, you need to put back in a 190 to 195degF thermostat, NOT 180degF

Engine coolant/water temp between 190-220degF gives lowest emissions.
When cooling system temp is under 160degF computer runs engine Richer which will have higher CO emissions.
This is why you only test emissions on a fully warmed up engine, i.e. 200degF coolant/water
You were tested without a fully warmed up engine, no thermostat, so CO would be high

The guy who changed your head gasket is a bit misinformed on how thermostats work.
A working thermostat prolongs the life of any engine, at 200degF oil stays cleaner and engine burns fuel more economically, everything stays cleaner.
Time spent under 170degF is when most wear occurs, i.e. engine warm up, so you want to spend as little time as possible running cold engine.

Strait water doesn't effect emissions, it causes corrosion and rust, it boils at 212degF and it has no "lube" for the water pump.
Coolant raises boiling point to 235degF, has corrosion/rust preventer, and lube for water pump.
Even a little coolant added helps.
A good 14psi radiator cap raises boiling point of water or coolant by 28degF, so you need that regardless.

 

[sithways]

Thank you everyone for your answers. I just have one more question:

1) If I want to replace the water with coolant, should I just drain the radiator and refill with coolant? Or do I have to drain the whole system?

 

[sithways]

That was a lie. I have one more question haha do you know if it is better to take the test on a full or half tank?

 

[sithways]

of gas

 

[RonD]

Well here is the "thing" about water and coolant.

"Water" is different depending on where you live.

Tap Water has minerals in it, minerals in this case is SALT, and salt causes corrosion, i.e. cars "that live" by the ocean or in areas where they "salt the roads" in winter, rust out much faster than cars "that live" in other areas.

If you have heard the term "hard water" in regards to your areas water then it would not be good to use in cooling system with or without coolant added.

All coolant makers use Distilled water in their 50/50 pre-mix, and only recommend Distilled water to add to any coolant, concentrate or pre-mix.
Because water varies by region coolant makers have to say don't use it, use distilled

Distilled water has the minerals/salts removed
This is not "bottled water" which will have minerals/salts in it.

Distilled water is just that, distilled, water is put in a pot and boiled, the steam from that water is condensed in another container, just like in the old "stills" for making whiskey.
So minerals and salts stay behind and only the water makes it to the other container.

So up to you really, if you have water with a "taste" then I wouldn't use it, so drain everything.
If you think water is OK then just drain rad and add coolant.
Nothing is going to blowup or in anyway effect smog test or even engine reliability
The minerals just make coolants anti-corrosion additives less effective.

 

[Napabandit]

Losing a headgasket can cause coolant to contaminate your O2 sensors and catalytic converter. Mine died a slow death from that. I replaced mine and my emissions were perfect after. I had high HC, NOx and CO with the old cat. New one worked wonders.

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