CEL + Poor emissions. Troubleshooting.

I'm running out of time before I have to go back for the second emissions test on my 95 Civic. I failed it in June, I was given until October. I've been dealing with this the way I usually do, which is basically to ignore the problem until the last second.

That's pretty much now.

I'm trying to figure out what exactly caused these readings. That's right. Waaay over the limit there.

I had a new cat on the car when I tested, so that's probably not it.

The only thing I can hazard a guess at is that my MIL (or I guess most of you guys call it a CEL) turns on randomly when I'm driving sometimes. It's been happening more frequently lately. It never stays on when I start the car. It only comes on whilst driving.

I did read the code. It's throwing code 43. (Fuel System). I'm wondering if this is related or a separate problem.

Any advice? I admit I'm in over my head here.

How old is your 02 sensor?

I don't know...

Older than it should be I guess. I assumed that if it went bad, OBDI had a code to throw for it, but I guess I could be wrong.

The car is obviously running insanely rich, so I suppose that could be the answer.

Would a faulty o2 sensor really cause that much trouble though? And why does the light only come on intermittently? These are the questions that confuse me.

Wow, so I'm not the only one who puts off stuff, hoping it will somehow disappear?

I used to own a '92 Civic, I now own a '97 Civic, and my experiences with 4 Honda products: you would have to be pouring gas through the engine to get such high emissions readings. You must be getting about 15 miles to the gallon or have huge clouds of smoke following you to get these readings. But, that doesn't tell you what is wrong, does it? Have you checked the "simple stuff"? What does your air filter look like? What's the cooling system doing?

I've had cars that have had mils/cels come on, it was almost always intermittent. Makes me wonder whether the prob you have is engine speed related. Sorry I can't be of more help.

Air filter looks good, and near as I can tell, the cooling system seems to work fine too. Also, I'm still getting 30 MPG, give or take. The only indicator that anything's wrong (besides the light and those readings) is a strong smell of burnt gas from the exhaust.

Hmm, "strong smell of burn gas..." Again, I'm no mechanic, but since gas mileage isn't suffering, could it be a timing/ignition problem or the valves are ....trying to think how to word it, the valves might be ....disintegrating? I don't know if you are able to do it, but a leakdown test might be in order.

High hc can be running rich maybe unburnt fuel you're smelling. Ignition weak, clogged air filter, vacuum leak maybe bad fuel return line. Rich condition can kill an 02 sensor. Maybe full tune up, check vacuum lines. Also check for any exhaust leaks.

Great. Now I have to learn how to check vacuum leaks.

http://www.amazon.com/CRC-05063-Guaranteed-Emissions-Formula/dp/B000CIPUR8

Guaranteed to Pass. This has helped me more than once. Read the instructions, you have to burn through most of a tank with the additive before filling up again. Then test. Of course it fixes nothing. I usually just get it at Kragen.

That just might be worth trying. I guess I have some work to do.

exhaust leak upstream of o2 sensor?

That guess I seriously doubt. I have a one piece header on there. The only gasket ahead of the o2 sensor is new

unfortunately obd1 codes are extra vague guesses at the problem, unlike obd2 codes.

does the car have a vacuum operated fuel pressure regulator? if so pull the vacuum line and smell for gas. ive fixed several makes and models that had a ruptured diaphragm in the regulator that caused the engine to suck in copious amounts of gas through the regulator's vacuum line.

If you have a header, how close to the cyl head is the O2 sensor ? If too far away,it can give false readings. Also, is it on the collector or on one of the primaries ?

I don't know what kind of FPR it has, I'll have to look it up I guess.

The o2 sensor is kind of far away. It's almost at the cat. If that's the problem, how would I fix it?

Checking for vac leaks is a piece of cake. Get a can of carb cleaner / starting fluid or even brake parts cleaner. With the engine running, spray the vac lines/ connections and everything that holds vac one at a time. When the engine races... Voila! you've located your vac leak.

The location of the O2 sensor really shouldn't be much of an issue as long as it is upstream (ahead of the cat). Although, I could be wrong. It's happened before

Yeah I don't think it's the location, because now that I think about it, this problem started occurring before I had my header installed.

Vacuum leak check next weekend? Guess so. I need this car squared away before I move