Just failed emissions twice

[Matt Timion]

My wife's CRX is due for renewal. We took it in for emissions and safety the other day. The emissions as 10mph passed, but failed at 25mph. It failed on the NOx, and was over by around .3 (should be .9, read at 1.2).

I replaced the sparkplugs, warmed up the car and took it back.

This time it was over 2.0 at both 10mph and 25mph. It was also overheating like crazy. YOu try driving home with the heater on in 90+ degree weather in the desert... argh.


Anyway, the next shot is to replace the o2 sensor. I'll use the one from my civic as I don't need it any more. The guy said that my new plugs might not be gapped properly, but I was hoping that wasn't the issue b/c I bought the "pre-gapped" ones. That's what I get for spending extra money on spark plugs.

Can anyone think of what might cause high NOx emissions? Is it possible that it's time for a new catalytic converter?

[SVOboy]

Is it possible to give her your second cat when you hook up your test pipe?

[maxc]

Originally Posted by Matt Timion

My wife's CRX is due for renewal. We took it in for emissions and safety the other day. The emissions as 10mph passed, but failed at 25mph. It failed on the NOx, and was over by around .3 (should be .9, read at 1.2).

I replaced the sparkplugs, warmed up the car and took it back.

This time it was over 2.0 at both 10mph and 25mph. It was also overheating like crazy. YOu try driving home with the heater on in 90+ degree weather in the desert... argh.


Anyway, the next shot is to replace the o2 sensor. I'll use the one from my civic as I don't need it any more. The guy said that my new plugs might not be gapped properly, but I was hoping that wasn't the issue b/c I bought the "pre-gapped" ones. That's what I get for spending extra money on spark plugs.

Can anyone think of what might cause high NOx emissions? Is it possible that it's time for a new catalytic converter?

Is the egr valve working. That's for NOx.

[Matt Timion]

Originally Posted by SVOboy

Is it possible to give her your second cat when you hook up your test pipe?

I was actually just thinking about that. I might do it if the next plan fails.

High NOx apparently means it's running lean, which is also shown by it always overheating. Perhaps the new O2 sensor will fix it. Thanks for the 411 bagpipe goatee.

[Matt Timion]

Originally Posted by maxc

Is the egr valve working. That's for NOx.

I'm unsure if they had EGR valves in 87. Since my 89 doesn't have one I think they didn't have EGR valves. I'll double check though.

[SVOboy]

The only civics that got egr until 01 were the FE models, and I think the crx is an si, so I doubt it'd have it.

[krousdb]

Clogged injector? Low fuel pressure?

[SVOboy]

Hey, I suggested low FP also!

Anyway, I hope I live to be old enough to see a clogged injector on a honda, but Iono, seems improbable,

[Ryland]

the 180F thermostats are stock for reduced nox emissions, if you are running a 192 thermostat for better mpg it's going to hamper your emissions test.

the side gaped/pregaped plugs don't alwas agree with honda's, I've had best luck with NGK plugs, they only last 15,000 miles, but the copper core conducts better then platnum, altho platnum never wears out.

try running some fuel system cleaner if you haven't already.

if you have an EGR valve it will be listed on yoru under hood lable, my 85 crx hf has an egr valve, along with my 84 civic hatch back.

[MetroMPG]

Also, is it running hot because it's lean, or is it lean because it's running hot? If you know what I mean.

[Matt Timion]

Originally Posted by MetroMPG

Also, is it running hot because it's lean, or is it lean because it's running hot? If you know what I mean.

I know exactly what you mean. Tomorrow I'll swap the o2 sensor. I tried to do it tonight but it started getting dark, and in my "old age" I'm developing the inability to see very well at nighttime. I also realized I'm going to have to solder the wire for the o2 sensor if I want to use the spare I have.

[DirtyOldTown]

Fix the overheating first. NOx increases with the temperature in the combustion chamber, and overheating will cause an increase in NOx. It's also possible that your EGR valve is not working, but I bet it's the overheating. You said it was worse the second time around when the car was warmer, right? To test your EGR valve, apply vacuum to it while the the engine is idling with no load. The engine should sputter or stall. If the idle doesn't change, then the EGR system isn't working. Could be a bad EGR valve or a clogged passage. Check for coolant leaks as the cause of the over heating. Also, make sure the fan(s) is/are working. I agree with Ryland about the NGKs - It's all I put in Hondas, and it's what the come with from the factory (those and Densos). If it's overheated pretty bad you may want to check that the head gasket didn't blow - Civics will do that when they get hot. Does it smoke?

[Matt Timion]

No smoke.

Just checked parts sites and the 87 CRX Si doesn't have an EGR.

Just a bit of info I didn't mention before. The PGMFI light would come on every once in a while. I checked the code on the ECU and it said the problem was either the spark plugs or the O2 sensor. This is why I think replacing the o2 sensor will help.

There are no coolant leaks that I know of, but I'll double check anyway. Oil is always clean so odds of a headgasket being blown are low.

I'll get some NGK plugs and put them in. Any idea where I can buy them? Pepboys? Napa? Honda?

[95metro]

NAPA seems to prefer NGK in my area. At least that's what they gave me for my Toyota a few years ago.

[Matt Timion]

Originally Posted by 95metro

NAPA seems to prefer NGK in my area. At least that's what they gave me for my Toyota a few years ago.

[Mr. Burns]Excelllent[/Mr. Burns]

I'll putter on over there today and get some new plugs for my n600 and the CRX.

[JanGeo]

arg lost the post ended up in advance -

cut out the fuel additives there is a theory that acetone interacts with the O2 sensor and makes it run lean - retard your timing and cold air instead of hot air intake.

[Matt Timion]

Originally Posted by JanGeo

arg lost the post ended up in advance -

cut out the fuel additives there is a theory that acetone interacts with the O2 sensor and makes it run lean - retard your timing and cold air instead of hot air intake.

This car doesn't have any fuel saving mods.

[JanGeo]

Just the high temp ... humm you would think that the ethanol would help it but as we all know the difference is not oxygenating the fuel as expected . . . maybe time for some carbon rich fuel additives then!!! And lower thermostat to run cooler - come to think of it if you are lean it will run HOT and make more NOx right??

[DirtyOldTown]

Usually when head gaskets blow on these things, the oil never gets contaminated. The gasket will allow coolant into the comb. chamber and it will smoke (steam) out the tailpipe - this is just from my experience with Hondas, not other brands. Since you have no smoke, the head gasket is probably okay. If your old plugs look unusually clean, that's a sign of a blown gasket as well. How's your thermostat and EGR valve? How does your radiator look?

[Matt Timion]

Originally Posted by DirtyOldTown

How's your thermostat and EGR valve? How does your radiator look?

Once again, no EGR Valve on this car.

I'm assuming the t-stat is fine, but I have no plans on replacing it unless it's stuck open or shut. Both rad hoses heat up, so I'm assuming it's fine.

[krousdb]

The VX just failied emmissions also. Not ONx but HC. I googled it and found these common causes of failure..

EXCESSIVE HYDROCARBONS (HC)

These emissions result from unburned fuel. Check the following areas for problems:
- Internal engine trouble
- Faulty air pump
- Ignition system
- Exhaust gas recirculation system (EGR)
- Catalytic converter
- Gas Cap

EXCESSIVE CARBON MONOXIDE (CO)

High amounts of carbon monoxide occur in a rich fuel mixture, meaning there's either too much or too little air reaching the combustion chamber. Check for problems with the following:
- Mis-adjusted carburetor
- Faulty fuel-injection system
- Dirty air filter
- Worn rings or valve guides
- Air pump system

OXIDES OF NITROGEN (NOx)

High levels of NOx can be caused by excessive temperature in the combustion chamber of a damaged catalytic converter. Check for problems with the following:
- Air injection system

- EGR system
- Combustion chamber deposits
- Dirty fuel injectors"

[Matt Timion]

Originally Posted by krousdb

These emissions result from unburned fuel.

Well krousdb, looks like it's time for you to buy a fuel atomizer!

(this post was a joke. Please don't mistake this as an endorsement for a product that doesn't work.)

[95metro]

The only things I can think of that affect NOx are the O2 sensor and the cat. A lean mixture would increase NOx. If the cat is rattling (breaking up inside) then it needs replacement.

[krousdb]

Originally Posted by Matt Timion

Well krousdb, looks like it's time for you to buy a fuel atomizer!

(this post was a joke. Please don't mistake this as an endorsement for a product that doesn't work.)

No, what I really need is an "Easy Button".

[Matt Timion]

Originally Posted by krousdb

No, what I really need is an "Easy Button".

Here you are

[brick]

Originally Posted by Matt Timion

Here you are

Don't get your hopes up for that one. We've been using an easy button at the office for weeks and it's a big disappointment. (Seriously...one of our admins got one and put it on her desk.)

Dan's problem is encouraging because excessive hydrocarbons = should be using less fuel than it is, hence the potential for huge numbers once he has it in tune. Of course, I'm assuming that it won't be a huge $$ fix...

Hope you guys get these cars running right!

[krousdb]

Yes, better FE if I can fix it. Wodering how the gas cap can lead to high HC?

[Gary Palmer]

Matt: I don't know what you've done, already, but from my perspective, I'd try to find out what is causing it to overheat. If your having to run your heater as an auxiliary radiator, something's either causing it to lean out, tremendously, or your thermostat isn't opening, or something. I've had a lot of problems with my 87 Civic, in regard to overheating, but I am pretty sure that most of my problems stem from a loss of fluid, when the system get's under pressure. Every time I check, it is only down maybe 2 cups of water, in the radiator, but that 2 cups is enough to make the thermostat not get water, and hence it doesn't open, which in turn causes it to get hotter, which in turn causes more pressure, causing more water loss. In every instance, when I have checked it, it has been down by a couple of cup's of water.

In my case, I found I had a radiator which was getting pretty tired, which I have replaced, but which hasn't really been tested because it's sitting, waiting for me to finish figuring out a totally unrelated issue.

In any case, on the 87, the radiator seems to sit lower than in the 89, and it seems to be extremely critical for all of the air to be evacuated, all of the time.

Good Luck

[Matt Timion]

Thanks Gary. As soon as my wife gets home I'm going to check her radiator level... well, the car cools down at least. I also bought some NGK spark plugs for it a few minutes ago.

I might get a new radiator for it if it's losing coolant, which I'm certain will fix the overheating.

Fon't forget, the ECU told me to check the spark/o2 sensor a while ago, so I'm also sure that it's part of the problem.

[95metro]

Originally Posted by Matt Timion

I also bought some NGK spark plugs for it a few minutes ago.

Was I right? Did NAPA stock 'em?