Failed Smog – 92 Civic – HC:244, CO:0.75, NOx:3154

[Aaron Sole]

It’s a 1992 Honda Civic DX 1.5L 4-Door – D15B7 Engine. Odometer reads about 150,000, but that’s not accurate. No idea of the true mileage. This model has no EGR system as far as I know.

I’ve done basic maintenance like an oil change, transmission fluid change, spark plugs and wires (didn’t replace cap and rotor because I’m cheap), and the air filter. Good thing to note, one of the old spark plugs was cracked where the white part is.

Those smog results are after basically just changing the O2 sensor and PCV valve. I was hoping the O2 would do the trick, and of course, I’m an idiot. Changed spark plugs after that test you see there. So maybe the broken spark plug could have something to do with something.

I’ve put in a new oxygen sensor, PCV valve (grommet was really dirty. Should I replace that as well? I tried to clean it out with a few q-tips.), fuel filter, thermostat, radiator drain and fill, and I put a new exhaust gasket in after the cat because it was leaking, but I don’t know if that matters since it’s after the catalytic converter.

I actually failed twice. I have no idea what I’m doing. The first time around the O2 levels on the smog test were .9 and .8. Second time around with some new parts, I think it was the O2 sensor that changed this reading, the second smog check showed the O2 at 2.8 and 3.0. And the CO2 levels went down about 2%. HC, CO, and COx got worse the second time, lol. Ignition timing was at 18BTDC at that time, and hopefully I adjusted it correctly now to 14-16.

I actually also tried pouring in a bottle of CRC Guaranteed to Pass. Burned it off and put in new 91 Chevron. I’m sure it’s helped some people, but didn’t help me and I still failed the 2nd smog test. Also not sure if 91 gas helps either. But hey I was desperate, and it was worth a shot, and now I’ve learned my lesson, lol.

-Compression test w/o foot on pedal: 165, 160, 162, 161
-Vacuum Gauge test: 19 in. Hg
-Adjusted timing from 10BTDC (which is what it was when I bought it a week ago) to now around 14-16BTDC. 16 is spec I think.
-Tested the catalytic converter with an infrared thermometer. Results unsure. When just idling, it seemed like the outlet was 30 degrees F cooler. After warming up and with the car revving with a stick on the gas, it seemed like the outlet was much hotter than the inlet. I can’t remember the exact numbers.

I did something strange. Water de-carbonizing? I removed the vacuum line from the brake booster to the intake? And I sprayed boiling hot distilled water very very slowly into there, reconnected the vacuum gauge and would wait inbetween more sprays. Motor oil is watery now, but I’m not sure if it was because of this or if I have a coolant leak or what have you. Is it imperative that I change the oil right away, or can I wait after other testing and repairs? I plan on doing the same thing but with Seafoam this time.

The car spews so much white smoke during warm up, but after it warms up, it stops, and blows clear as day. It is 30-50 degrees F here.

My ECT connector had electrical tape around it, one that came apart, and I saw green corrosion. So I snipped it off and tried testing it with a crappy ohmmeter. Just the leads touching each other it shows 1.3. Shows maybe 1.5 on both wires in the ECT connector. Was hoping it was just corrosion but it seems like maybe the wires are fine. Haven’t checked the actual ECT sensor.

I tried, hilariously to find vacuum leaks. I basically just sprayed carburetor cleaner all over everything under the hood, lol. Results un-conclusive.

Tried to find exhaust leaks too put putting a rag in the tailpipe. Only smoke I saw coming out was the gasket after the cat. So it was $4, out of desperation of trying anything, I replaced it, no idea if it matters.

I’m planning on taking off my cat and putting it in soapy water overnight. Saw Scotty Kilmer do it on Youtube. The cat might have a tiny tiny rattle in it, I’m not sure. It is so expensive, so please don’t break my heart with things like the truth.

Thank you Eric. Your videos have been amazing. University of ETCG. You could train a group of super soldiers, who fight crimes against cars all over the world, and specialize in secret CIA missions where a master mechanic is needed. I would attend that elite university. Or you could make a TV show out of it, and have challenges, and people voted off, lol. Put it on YouTube, who needs television anymore. That would be cool. I’m quite serious, lol.

Topic

[Lord Ihcalam]

drive 5 hours north and register it in Oregon no emissions testing here 🙂

[Josh]

I live in Oregon and everywhere I have been requires emissions testing. Do you have any cel? Might be a ecu thing.

[Aaron Sole]

Nope, no check engine lights. I want to remind everyone that I am an idiot, and for many of the tests and things that I’ve done, I have no idea what I was doing nor do I know the actual reason for doing them, lol.

[Lord Ihcalam]

you live in portland. portland requires testing. so does most of the rest of the 5 corridor. contrary to popular belief by people that live on that side of the state, oregon doesnt stop at the moutain passes *I* live in oregon on the east side of the cascades and we dont test. otherwise two of mine would fail massively since they dont have cats and smoke like chimneys.

You can try cleaning the cat, it might help some. I’ve heard having a hotter plug in the car helps too. higher octane on a car not designed for it might make the issue worse. check your cap and rotor see if theres wear or soot or deposits on those parts.

[Josh]

OK, just note I am only a tech in school; what I would do is make sure the basics are done. Check oil, coolant, I would even check to see what the spark plugs are doing. You may not begetting a complete burn of fuel.

[Aaron Sole]

So I just did something amazing. Yesterday when I put water through the vacuum line from the brake booster to the intake, I had a stick on the gas at a higher RPM and everything was fine. I looked at the ECT connector and it saw green corrosion, so I cut it out, tested it with an ohmmeter, think it’s okay, and then I reconnected it.

While I was reconnecting it, the two bare wires touched each other a few times. I heard a click from the fuse box. Maybe it was just the relay clicking, maybe a fuse blew. I turned the car on, and as usual, a lot of smoke. Put a stick on the gas, waited about five minutes, and the smoke stopped. Started putting seafoam through the vacuum line.

Maybe 15 minutes later, I see a mountain of steam come from the radiator, and I think one of the radiator hoses blew as well. The temperature gauge in the car was at high, lol. First time I’ve ever seen that. Quickly turned off the car, and the radiator was just exploding with steam. All the coolant spewed out.

Last night I actually had the ECT disconnected, and the car was running and I was trying to see if the white smoke would disappear just simply by warming up the car, which I confirmed. I caught the temperature gauge getting abnormally high and shut it off in time. It was of course because the ECT was disconnected.

So uh first of all, man I am awesome. So the ECT was working fine before I had cut it out and reconnected it and had the two wires touch each other. So what did I break and how do I fix it? And what do I do with my radiator now? I think I might need some new hoses at the very least.

But more importantly of course, I really need to pass smog and if someone can help me, I would just scream in joy.

[college man]

you need to get the cooling system back together.fix the wires
to the coolant sensor.get that to read to the computer to adjust
fuel and bring the cooling fans on. replace any bad hoses. At this
point flush the old coolant and refill with new.bleed the system of air.
Part of your problem may have been the coolant sensor not reading.

[Aaron Sole]

Lol, I had just forgotten to connect my radiator fan. Just ran the car for half an hour at high RPM and put Seafoam through the vacuum line, and it was fine, didn’t overheat at all, all the hoses are fine as well.

Also, about the white smoke, I think it may be normal, maybe. I just tried my other car, a Corolla, and during cold start up, it smoked a lot as well. After a minute of 4,000 RPM, smoke went away, and it blew clear. The Civic just takes a little longer to blow clear after a cold start up. And it’s 30-50 degrees F outside.

So anyway, besides this radiator incident, how do I pass smog? What is causing my high emissions?

[Josh]

I want to say it could be a bad cat. But I would double check your ecu to varify its working as it should. So as a precaution plugi a scanner.

[Aaron Sole]

I suspect a bad cat as well, but I don’t want to guess at it. I’ll probably re-do the pyrometer test. I’m also going to try soaking the cat in soapy water overnight. My coolant fan is working but it seems like my exhaust manifold fan is not working. So I’ll try to look into that but again, I have no idea what I’m doing, lol.

What else might it be? Because I know people who have replaced catalytic converters and yet still have failed smog, and I do not want to join that group. Worst of all if my current cat was in good condition and was replaced needlessly and welded on needlessly. Maybe the cat will get me to pass smog, but if the cause of a bad cat isn’t addressed, you’d have to buy a new cat come smog season again. Don’t want to put an expensive band-aid on it if it is that.

What else might cause high HC readings and 3000+ NOx readings, along with 3% O2?

[college man]

usually high hc is from unburned fuel.look at your ignition system.
plugs,wires,cap and rotor. try doing a power balance test.

[Aaron Sole]

I think I’m running lean. Again, I don’t know what I’m doing so please correct me if I’m wrong.

The old spark plugs were unusually clean. White as bone. Except one was broken at the white park and burnt. I replaced them.

I also had an acceleration hesitation and performance loss. That was when the car was at 10 BTDC. It’s now at 14-16 and doesn’t have that problem so much and performance is much faster and better.

Warm-up was definitely much too lengthy, but I think less lengthy now after some general maintenance.

Maybe once or twice it had trouble starting. I gave it some gas and started it, but I don’t know if putting my gas pedal down while cranking really helped. Saw it on a tv show once? lol.

Lean air/fuel can cause high NOx. And I believe lean air/fuel can cause high combustion temperatures, which in turn causes high NOx. Please correct me if I’m wrong.

Also the higher O2 levels in the smog test, at 3.0%, also seems to indicate a lean condition.

And my exhaust fans seems to be not working. This might also contribute to higher temperatures.

But the question is, even with all these things, are these things alone capable of producing monstrously high NOx levels of over 3,000?

Maybe I’m wrong and maybe it’s something else. Maybe it’s a bad sensor sending crazy readings causing the engine to run strange. Maybe all of this is irrelevant and it’s simply a bad cat, and a bad cat alone. Maybe it’s a dirty fuel injector, though I did just do a seafoam treatment, but maybe it was the wrong vacuum line and didn’t get all four cylinders. Maybe there’s an air leak causing excess air to get in. Maybe I’ve got air pirates coming to steal me booty. Maybe there’s a head gasket problem. Maybe I’ve got a fuel pressure problem. I opened my fuel filter and switched the key to ON like Eric did and quite a lot of gas squirted out. But I haven’t done a fuel pressure test yet. Maybe I should do that next. Maybe the car will pass smog right now. I don’t know, I just don’t know.

Next I’m going to test the fuel pressure and spray carb cleaner around looking for leaks and see about the exhaust fan.

[college man]

first as I stated before.get the cooling system corrected.
you need to fix the fan.check for 12v at the fan.if you unplug
the coolant sensor connector.use a paper clip and bridge the wires
and the rad fan relay should make and the fan should come on.
if not test at the fan itself.

http://www.smogtips.com/failed-high-hydrocarbons-HC.cfm

[Josh]

Do everything Collage man said first. You have to get your cooling system in perfect working order first. Now that I am out of class for the day and my brain is working better, You have a vary lean fuel burn condition. I would actually put fuel injector cleaner in the tank and run the car. next I would I would find an empty road and just floor it. That will increase your fuel preasure and hopefully help clean the injectors. For your vary lean burn, I would check the ignition wires and spray water on all the cables that are vary close or touching to see if you have an ignition leak. You might have low voltage at the electrode and that could be causing the fuel not to burn all the way. But I really urge you to follow Collage man here. He knows way more then I do.

[Aaron Sole]

Cooling system is in perfect working order now. It was just corrosion at a wire on the exhaust fan. Both fans work perfectly.

I’m more concerned about the NOx than the HC. What could cause 3,000+ NOx? It’s insanely high, it’s 4 times over the limit, and 6 or more times over your typical car.

Had 2 different fuel cleaners and burned both of them off in two tanks at two different times. Seafoam through the vacuum line straight to the injectors will clean them out much better though, which is what I did. I’ve been going full throttle on this thing many times like it was on fire and I was trying to put it out with the wind. A lot of fun. I’ve sprayed carb cleaner and brake cleaner over everything under the dash, and focusing on hoses and even on the injectors and the entire lines themselves. Gone through a whole bottle. Doesn’t seem to be any leaks. About checking for ignition voltage, what am I looking for when I’m spraying water on them? I’ve never done that before.

[Author]

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