I have been reading about these emission test fail in this forum and now it is my turn. It appears to me that each case is different (could be b/c I don't really know what I am looking at). So here is another one with possibly a unique case. It is unique b/c I have not seen others here with this case. My CO is very high as can be seen in the attached photo. The rest of the numbers are very good. This 1994 accord only has 85593 miles.

I was asked when the last time I had a tuned up (don't know the answer and not original owner). They suggest I get the tuned up for $400 and go from there. as you might have guessed, I decline the tuned up. They said it might fix the CO but most importantly I don't have $400 to spare right now.

I plan to change the spark plugs and engine air filter myself. Just changed the oil last month.

One thing I noticed with this car is sometime when I pressed on the gas, I feel a little hesitation and car feel like it is about to stall (does not happen all the time but once in a while). Is that a sign of mis-fired? and would that caused the very high CO reading?

Thanks for reading and hope someone can explain the hesitation and High CO reading.

 

CO and O2 readings are used to determine rich/lean condition. Excessive CO the engine is running rich, excessive O2 the engine is running lean.

Currently your CO is really high(rich) indicating unburnt fuel, this will also increase HC emissions. You will want to see something closer to a hundredth of a percent .0#%

O2 should be less than 1%, and by less than 1% I mean not much at all, like .0#%. According to the readout it is 16%. Either there is an exhaust leak before the O2 sensor or there is an intake air leak.

CO2 would be best at 15%

HCs should be in the teens.

I don't see a timing indication readout. Warm up the car, turn it off. Jumper the blue two wire connector that is behind/below the glove box door.
Turn the car to ON, watch the check engine light for any codes. Record them.
After that start the car, with a timing light verify that base timing is correct. There will be a red or yellow marker on the balancer as well as a white one. Correct base timing is when the #1 timing is lined up with the colored mark.
When done, turn off car, remove jumper, and replace blue plug.

FWIW had the '97 Sedan EX smogged earlier this year 150K miles.
15MPH__1787rpm__15.1%CO2__.1%O2__HC@15ppm__.03%CO_ _NOx@15ppm
25MPH__1890rpm__15.1%CO2__.0%O2__HC@7ppm__.02%CO__ NOx@74ppm


With your car I would start with the easy/free things.
Go to the FAQ at the top of the forum and dig up the EGR cleaning procedure for the '94-97 Accords. This will reduce NOx emissions and most likely improve the off idle stumble/lean misfire you encounter.
I would not use a carb/throttle body cleaner as this just gums up the carbon. Use various sizes of flat heads to clean out the EGR manifold and the ports. It will mostly scrape off like the dried grease/soot from a BBQ kettle.

Open the distributor cap. Look for worn or corroded terminals inside the cap. I have found that a yellow 'booger' or corrosion builds up on the cap terminals, this will reduce spark power. Gently scrape the terminal with a small screwdriver the crud will pop off. Wipe the inside of the cap clean of any dust residue.

Pull the spark plugs and see what condition they are in and if the gaps are correct.

Remove the exhaust manifold heat sheild and look for cracks in the exhaust manifold.

Cheap
Purchase a couple of cans of Sea Foam, and follow the directions for adding to gas, crankcase, and the intake. There are how too videos on You Tube.
While adding SeaFoam to the intake look for any exhaust leaks from the manifold to the catalyst.

 

I just found a DIY video on cleaning the EGR. I will replace air filter, spark plugs, clean EGR, pull the CEL code if any. Will start on those first as they are something I can do and report back their conditions.

As far as reading timing light, I am not very familiar with that. I am not able to follow your timing light instruction and not sure what the red/yellow white markers are until I do more research and try to understand what the purpose of it. You have been very helpful!

 

You will need to use a timing light.


The black and red alligator clips attach to the battery. The inductive pickup(red plastic lead) will need to be attached to the #1 spark plug wire. On Accords the spark plugs are 4-3-2-1, you will attach the lead to the #1 sparkplug that is farthest to the right(nearest to the oil fill cap). There will be an arrow on the inductive pickup usually it will also say 'PLUG' the arrow should be pointing towards the spark plug.

With the engine at full operating temp, turn the engine off. Jumper the blue two wire connector that is below/behind the glove box.

Restart the engine, and point the timing light down at the crank pulley, you should see a pointer on the timing belt cover sticking out, and the crank will have a red or yellow marker on the pulley.

Using the timing light, line up the pointer and pulley. If timing is correct the timing light will flash when the pointer and red mark on the crank pulley line up. If the light flashes between the red(base timing) and white(TDC) marks then the timing is retarded, if past the red(base timing) mark the opposite way then the timing is too advanced. Adjust to correct.

 

The reason for high CO content in emission can be due to dirty or clogged Air filter. The reasons can be faulty O2 sensor, defective MAP sensor or faulty Engine Coolant Temperature sensor. First you should try cleaning or replacing the air filter as it is the cheapest. For further assistance you can visit http://www.smogtips.com/failed-high-...onoxide-CO.cfm

 

Hi, just wanted to say thank you to Mad Mike and Marshall for your helpful inputs.

Mike, thanks for spending the time to explain to me about the timing light. That is something I am sure is very easy to understand for alot of folks but for me, it is way beyond my comprehension even with the detailed steps drawn out. I will leave that to the professional folks. :-)

As you all might have guessed, I have been busy trying to fix this and I only had 1 chance to fix it and get a second test done for free and did not have the luxury to try different thing in stages.

I ended up replacing the 4 spark plugs. Replaced the engine air filter. And cleaned the EGR ports.

The old air filter were not bad (does not look too dirty) but when I place the old filter up toward the sky, I could not see any sun light passing through. I did the same thing with the new air filter and I could see sun light coming through the new filter. So looks can be deceiving and lord knows how long that filter has been in there.

The EGR ports were also clogged. 2 were almost clogged completely and the rest were partially clogged.

With these 3 fixes, the second smog test passed very easy as I was told and comparing the old vs new test results.

Thanks for the help...

 

gotta love nyc for this one. since 94/95 are obd1, they only give us a visual inspection. no more crap into the tail pipe.

 

Would you post up the passing tests results please.
I am always intersted in seeing before/after changes when it comes to fixing an emissions issue.

Just cleaning out the EGR alone you will net a gain of 1-2 MPG.

Enjoy your new found economy and power.

Meh, I have come to find actual emissions testing to be a useful tool.
That NYC 'test' is a joke then, why bother at all.

 

Sure, noticed the diference in RPM for 25 mph in both test? I am not a mechanic so I don't know if what I did would make the RPM different. Car run ok for a 19 yrs old.

 

Higher rpm, most likely lower gear. Calif specifies an rpm range for a given speed on these tests. It's so a person cannot force/cheat the test.