Failed Smog - 92 Civic DX - High HC, CO, and Super High NOx

[some_other_dave]

Sounds like you're starting to get it sorted out, good for you!! The workshop manual should help quite a bit. It may make sense to see if any of your buddies like to work on cars; they can help read the diagrams and lend a "calibrated ear" and eye to check stuff.

Originally Posted by AaronMartinSole

Watched a short video of the PCV Postive Crankcase Ventilation system. I think a clogged PCV can cause high NOx readings, but I have no idea ...
So do I need to clean out the breather box? Is this part of the recommended and necessary maintenance?

EGR takes exhaust and pushes it back into the intake. Exhaust doesn't have (hardly) anything in it that can burn, so it mostly acts as space filler. As mentioned in one of your later notes, it helps bring combustion temperatures down which reduces NOx formation.

PCV takes air (which has O2 in it which does contribute to combustion) from the crankcase that has oil spray and vapor in it. It separates out (much of) the oil from the air, and feeds the "dirty" air into the intake, where the oil gets burned in small amounts. That helps keep things cleaner, and helps reduce the pressure inside the "bottom end" of the motor, leading to fewer oil leaks and other problems.

If the PCV system started out clean (and it probably did), then it's not a bad thing to un-clog it and clean it up. It probably won't help your NOx emissions appreciably.

Also I just changed my manual transmission fluid using AMSOIL Synchromesh or something. ... I filled it with the car on jack stands. Someone recommended that I let the car down, then fill it. How do I know it has the right amount without a dipstick?

I know that in the older Hondas, the factory manual called specifically for 10W30 or 10W40 engine oil to be used in the transmission. Some current manual transmission oils are actually too thin and can allow damage to occur inside the transmission. I do not know if the oil you used is one of those, but it's worth looking in the manual to see what they have to say about recommended fluids. If motor oil is specified, I would use that--it's cheap and is the "right stuff", after all.

If you fill the transmission with only the nose up in the air, you will not get enough oil in there. I know this from my car; I killed two transmissions over the course of 100,000 miles by chronically under-filling them.

There are two plugs on the transmission, a drain plug and a fill plug. The fill plug was hard to reach in my car; I got a 17/19mm box-end wrench specifically for that, and it was still sometimes difficult to loosen. Always remove the fill plug first, because if it gets stuck you can still drive the car. Removing the drain plug first means there's nothing in the trans if the fill plug sticks.

You fill the transmission with the car level until the fluid is level with the bottom of the fill hole. So basically until the fluid comes out as you put it in, or until you can reach in with a finger and feel the fluid level with the bottom of the hole. If the front of the car is tilted up, the fluid level toward the rear of the transmission (where the fill hole was in my car, probably in yours also) shows higher than the actual level. That's why you want the car level.

5.) I'm going to check for vacuum leaks? (no idea how)

That's always an interesting question. You can do stuff like have the car idling, then spray WD-40 at the end of a suspect hose. If the idle changes, it is likely because some of the WD-40 got sucked in, so that end of that hose is probably leaking.

6.) Check for a dirty MAF and clean it. (Car only has MAP - Manifold Absolute Pressure. Still researching.)

No MAF on those cars. A MAF is used in many cars to tell the engine how much air is going in, so it knows how much fuel to spray. Older injected Hondas use the pressure in the manifold (measured by the MAP sensor) to guesstimate the air going in, so they use MAP instead of MAF.

7.) Check throttle bodies.
8.) Check fuel injectors.
9.) Check air regulator or IAC.
10.) Replace fuel filter.
11.) Valve adjustment.
12.) Check for exhaust system backpressure.

I have no idea what these things are, what they do, or where they are.

The fuel injectors are what spray fuel onto the backs of the intake valves. They are on the back side of the engine up near the top. In between the valve cover (the thing the spark plug wires go to) and the manifold (the thing that says PGMFI on it) you should see the fuel rail. The injectors are sandwiched between the fuel rail and the cylinder head. I'm not sure how I'd check them, frankly. Maybe send them out--but then you can't drive the car while they're out.

The IAC helps control the idle RPMs. On my car, it was on the back of the manifold. It had an electrical connector and a couple of vacuum hoses hooked up to it. It had clogged up, so I was able to remove it from the manifold (space is tight!) and clean it out with brake cleaner, then put it back on.

The fuel filter on my car was a fat cylinder on the firewall to the left and back of the engine. There were two hoses that bolted up to it; one hose led to the fuel rail (see fuel injectors above). Replacing it was a bit of a chore; there are flats on top of the filter for you to use a big wrench to hold it steady while you loosen and tighten the bolts for the hoses. The hoses have specific sealing washers that must be replaced, so have those on hand as well if you try this. It was a real struggle to break the bolts loose on mine.

The valves are inside the valve cover. There is a specified clearance between the things that push on them and the end of the valve. That is measured with "feeler gauges", which are strips of metal with very very specific thicknesses. There is also some "feel" so you can tell if the gap is too loose or too tight; the first time I tried on my Accord I set everything up very loosely and the car would hardly run. That's where it is handy to have a buddy who can stop by and check your work.

The exhaust system is everything from where the header bolts up to the engine (that's the four pipes coming out the front side of the engine) all the way back to the tailpipe.

One interesting thing to add is the speedometer on this car is very erratic jumping everywhere. If I remember right it seems to work okay over 40mph.

Could be a cable that is going bad.



Good luck with the car!

-soD

[AaronMartinSole]

Drove this thing like it was on fire and I was trying to put it out with the wind. I have never gone full throttle before. It is curiously satisfying. But my goodness, full throttle on this old Honda is embarrassing, lol. Big automatic SUVs were still overtaking me with my foot plastered to the ground. But needless to say, I like manuals a little more now. I was warming it up for a smog check and burning off the CRC Guaranteed to Pass. Man the gas just wouldn't burn off. Thing is too efficient, lol. Put three bucks worth of Chevron Premium in it which will probably last me until next Christmas, went to the smog check place, and it was closed, but that's alright. We'll see tomorrow how it goes. I've got to double-check the timing one last time, and she should be good to go.

[AaronMartinSole]

Thanks Dave. I wonder what made my car stop spewing thick smog out of the tail-pipe. I thought it was the clogged PCV valve but from what you've said, maybe it was the new oxygen sensor instead.

Yeah I read up a lot on transmission fluids. I mean there's just an endless debate about it. Some guys swear by Honda MTF, others say Honda MTF is crap, is glorified 5w-30 with some additives, and that it's given them bad performance. Some guys swear by Pennzoil Synchromesh or GM Synchromesh which they say is the same thing, but they say there's a certain kind which is friction reduced or something like that. Some guys swear by synthetic 10w-30 or 40, other guys swear by AMSOIL Manual Synchromesh. The manual calls for 10W-30 or 40, but I think I might have read somewhere that the oil back then was different or that it was changed and now Honda recommends their MTF now instead, I don't know for sure. I remember reading something that seemed like it was official from Honda saying 10W-30/40 motor oil should just be a temporary use. The only reason that would make sense is either A. the oil back then was different or B. they changed their recommendation based on new information. I honestly would be fine with any of these options, but I kind of like AMSOIL. Maybe because it's harder to get and kind of somewhat more special in that sense, like a club, lol. Or maybe because the bottles are shiny and pretty heh. Or maybe because I believe they're better with all their testing that they show. I just want to see more independent oil tests. There was one oil test, some sort of wear test, that had a surprise shower: Valvoline Durablend. That's what I've got in the Civic right now. But who knows if it's the same stuff or if the test was done properly or anything. Maybe Consumer Reports or some other agency has done more independent and fair and reliable, unbiased testing. All I know is I love putting fresh fluids in. Like sweet honey.

I had filled the transmission supported on four jacks, the two back jacks an inch or two higher. I let the car down, opened the drain plug, put my finger in, and felt fluid right level with the bottle of the plug. Feels good. Great advice on trying to take off the fill plug first. Obviously I took off the drain plug first, lol, and had a heck of a time trying to get the fill plug off. Guess what got it off. A broken 1/2" torque wrench from Harbor Freight. Lol. It's a glorified breaker bar now. Hey, can't beat that right? Escalator becomes stairs. Thank you for the convenience.

Now a lot of people say those additives they sell at the auto parts store are just snake oil. I once thought so too. But I think a lot of them actually work properly used and understanding that no, they're not going to fix a mechanical problem and they are at best, a temporary or shot in the dark. Fuel additives however I think are good. I had a riding lawnmower once that was running really rough, and jerking me back and forth, no smooth acceleration. Put a bottle of I think Chevron Techron in there and it ran and accelerated smooth as a whistle after that. So I think for most fuel injectors, those could clean them fine. But I'm sure some are so bad they need to be taken out and sent to get cleaned.

Yeah I just changed my fuel filter. An Asian girl on YouTube showed me how. Another Caucasian girl on YouTube showed me how to change my serpentine belt. But I never did. I failed at that. Now I'm sure I could do it now but, belt is still sitting in the garage, six months later, lol. But turns out my old Carol Corolla didn't really need a new one, not yet, but she'll get it when she does.

Valve adjustments are fun. Feels nice to have all the valves properly set, all nice and even and everything. And hopefully it adds some fuel economy! Who doesn't like neatness and cleanliness and order? Feels like YEAH!

Hopefully after I get all these mechanical things sorted and the smog, I can start making over this old heifer. I want to do horrible horrible, unspeakable things to it, like colored windshield wipers and fake air vent decals and an LED light up shift knob. Oh man, why does that excite me so much. I'm so excited to do those horrible tacky things. But it might make some young kid very happy. "THIS IS THE COOLEST THING EVAR!!!" I haven't even begun thinking about eco-modding it. I wasn't planning on to actually. Wanted a car to look normal and maybe potentially half decent, not like my dear old Corolla Insight. Might attempt or at least start reading up about valve adjusting. Couldn't find a valve adjustment tool, so I got a nut driver and a wrench instead. And tomorrow is the big day, the SMOG TEST. Wish me luck.

[AaronMartinSole]

I fixed my erratic speedometer! Can you guess what it was? Corroded connector! A little baking soda, water, and a wire brush, and voila - I now know my vehicle speed. It's neat how the speed sensor dips into the transmission and into the transmission fluid. There's like a little wheel like a watermill. I wonder how it works, I bet it's interesting. I'd like a watermill and a little cabin by a river.

Took another WOT wide-open throttle trip. Beautiful street lamps and a night-time fog. Man it's fun going wide open throttle. I always thought that was bad for the engine. Maybe it is. But lol, wide open throttle on this little old Honda is the slowest thing ever, hah. I have to go wide open throttle while the mini-van next to me casually and without strain overtakes me. Fun though, these manuals are growing on me. Still prefer driving automatic though, but if someone took this manual away from me, I'd miss it.

[AaronMartinSole]

Turns out I had my timing all wrong, again. Third times a charm, hopefully. Still haven't got it down. But I saw a page in the manual that showed that rolling the distributor back towards the rear advances, and pushing it towards the front retards. I had it as retarded as it can get. Which completely explains the horrible performance and acceleration hesitation I was getting! I was thinking these old Hondas were kind of slow when really, they pack a punch! Man 1st gear wide open throttle is a treat.

Using the timing light, I saw two marks. One single white dash, and to the left of it, ahead of it while the belt is turning counterclockwise, turning towards the front of the car, is another white mark, with two I think metal marks on each side of it. I had it adjusted to the single white dash, thinking that was the intended spec. That was actually Top Dead Center TDC, please correct me if I'm wrong because I'm clueless. So I think the other white mark with the two metal marks on each side of it, ahead of the single white dash, is actually the factory spec, and I think the two metal dashes indicates the +/- 2 degrees of advancement or retard... ment.

Anyway, the engine performs beautifully now. Packs a punch. Hopefully the smog tech guy is nice and tells me what my ignition timing is, and if it's a little off, I hope he gives me two minutes to adjust it. I mean all you need is a wrench, undo three bolts, nudge it ever so much, maybe a mm, and that should do the trick.

[PaleMelanesian]

Originally Posted by AaronMartinSole

Just took out my O2 sensor. Goes right into the exhaust manifold, just like you said PaleMelanesian. Looked up Melanesian out of curiosity. It's like New Guinea and the islands off of the northeast coast of Australia. OOo Fiji is there. I never knew. Must be beautiful. Man I'd love to live on an island, like Hawaii or something. I've got family there and visited once. Screw it, maybe I should move to Hawaii. Sacramento is the worst place on the face of the earth, lol. I'll be on Hawaii's Craigslist.

Yep. I grew up in Papua New Guinea, but I'm of Irish descent. Put the two together to get my username. Yeah, the weather is nice there. I particularly miss it this time of year.

[some_other_dave]

Originally Posted by AaronMartinSole

That was actually Top Dead Center TDC, please correct me if I'm wrong because I'm clueless. So I think the other white mark with the two metal marks on each side of it, ahead of the single white dash, is actually the factory spec...

I believe you've got it right, now.


BTW, when I started monkeying around with cars, I used the John Muir "Idiot Book" as a reference. Lots of good info in there, written specifically for people who don't start out knowing lots of mechanical jargon and stuff.

There's actually a Honda "Idiot Book", but it only covers up into the early 80s. It still might be a help (I'm not sure frankly!) and may be worth grabbing used. Link to Amazon's page for the book.

One caveat: Those were the instructions I was using when I set my valve clearances to "way too loose". It is hard to convey in writing how the feeler gauges are supposed to feel when the gap is correct.

-soD

[AaronMartinSole]

Smog take 2. The free re-test. I told the smog tech what I did to the car. He said my readings were way too high and I probably wouldn't pass, that what I did probably wasn't enough. I said let's try it anyway. I had been there twice early in the day, but there was a long line. So I was kind of eager and impatient. So went ahead with it. And guess what happened? I failed, miserably! What lesson did I learn today? Listen to the professional. And patience.

Readings were even worse this time, across the board. Failed an extra category as well! Advancing timing usually increases emissions and retarding it decreases it. The first smog test I was at 10 degrees before top dead center. Bought a timing light and adjusted it, and it read 18 BTDC this time. Spec is 16 +/-2. So I want to aim to adjust it at 14. So that was the good news, and the only good news, that I passed the timing check.

I've attached the smog readings. Wish it was just NOx but it's the entire board.

At 15mph, HC worsened by 55 or 29%, CO by .04 or 5%, and NOx by 438 or 16%. Still exceeding by HC: 154%, CO: 34%, and NOx: 267%.

Interesting thing to note is that the O2 reading increased from 0.9% to 2.8%. Maybe that had something to do with the new O2 sensor? Or maybe it was the timing, who knows. I don't know what it means anyway.

Heater doesn't blow hot if that matters. All I know is that high NOx may be caused by really high temperatures or something. And I actually don't think the radiator fan is working. Gotta check that.

I thought I had solved the smog out of the tail-pipe problem and that's what gave me false confidence that I'd pass. But while he ran the car, it was smogging like crazy. I just don't know. Maybe I just didn't see the smog, maybe the car has to be in drive, who knows. I tried to see whether there was smog by putting the car in neutral and putting a stick on the gas. Oh but that's that.

So it's back to the drawing board. I'm going to find the problem. How much it's going to cost is the only question, heh.

I think I've got to check the catalytic converter. That being the most expensive repair, I was hoping it wasn't that and wanted to pluck all the low-hanging fruit first. But it looks like there's a good chance it might be. But we'll see. Might be running lean, might be a head gasket, might be anything, Shot in the dark. This is going to take a real stroke of something. But I'm still having fun and can't wait to solve this thing.

[California98Civic]

Sorry to hear this. I dread my next test. They're supposed to get more stringent, I hear.

[Rusty94cx]

I though it's been a long time since I lived in Cali that you could go to somewhere and if it was over 500$ to fix you got a waiver. It could be a bad head gasket are you using any coolant? If so then it's going somewhere. Cats usually get to plugged and melt. They clog. See if you get good pulses of exhaust out the back. Check you vacccum you might have a tired motor. So happy no smog check in my county. If you have black smoke out the tail pipe it's not lean its rich. In complete combustion.