faran

Guys-

My ole 1994 Honda Accord EX with AT failed emissions test today.

Everything looks just fine and within the limit, except CO% at 15MPH, please see attached report and advise how can I improve or have the car pass emissions test.

Oil and filter was changed less 1000 miles ago. Air filter, spark plugs/wires were replaced for last emission test(2 years ago). For rack and pinion replacement, middle pipe with O2 sensor was pulled and when it was tightened up, think it produced a miner exhaust leak in that area. Can that be the reason for failure at 15MPH, since at 25MPH pressure is more and less exhaust gases are leaking?

Please see attached emissions report and thanks for any of your input and help.

P.S: There is no CEL, car does not miss or have any other noticeable problem.

MAD_MIKE

Possibly running a bit rich.
Check your air filter is not clogged, two years is quite a while to not change.
Pull spark plugs and verify gap and wear.
If the distributor cap and rotor have not been repalced I would suggest doing so, verify the terminals on the inside of the cap are not corroded.

If you suspect an air at the O2 sensor, verify if there is or not, replace any applicable gaskets. Fresh air would cause the O2 to read 'lean' causing a rich response from the ECM.

faran

MAD_MIKE looked at your emissions post, you being my GURU(and an expert)I was totally expecting your help and response. How can I clean the terminal, by using sandpaper?

Can I try using steel band aid around the pipe area or proper gasket should be needed?

I am going to replace spark plugs and air filter. Is there a way I can actually see if there are any emissions improvements after the change?

MAD_MIKE

If the terminals are aluminum verify that there is no excessive buildup of corrosion. A gentle scrape of a flat head screwdriver is fine. Don't sand it, you don't want to remove material, just any possible corrosion/scaling of the terminal.

If you replace ignition components, plugs, cap/rotor, and wires drive the car for a while before going back for testing. New ignition components will have a hotter spark and burn off some carbon buildup that may affect emissions output.

holmesnmanny

Like mike said, i would say this is ignition related. Tune it up.

faran

Thanks so much Mike, I am going to make sure there is no exhaust leak. Replace plugs, clean cap contacts/rotor and Air filter.

One last question, are Spark plug wires necessary? Since I replaced them in 2013.

holmesnmanny

Nah, wires last a while, even the cheap ones.

faran

Thanks holmes. Could it be related to O2 sensor or small exhaust leaks? Can I try using steel band aid around the pipe area to stop exhaust leak?

holmesnmanny

Sorry I didn't catch the exhaust leak before. Normally you would have excess hydro carbons in an exhaust leak situation but I supposed it's possible.

You gotta understand what happens when you have an exhaust leak. The excess oxygen being pulled in from the outside air causes the oxygen sensor to think that it needs more fuel shot in to offset it. Normally you would then see this in the test in the forms of high hydro carbons. Since you're not, I'm not sure you have an exhaust leak.

With the car completely and totally cold, start it up and let it idle so it's already idling at 1500rpms, disconnect the vacuum hose going from the brake boost to the intake manifold at the intake manifold. Very lightly dump in a little bit of seafoam. It will leak out white smoke if there is an exhaust leak. You will see it. It's very important to just put a little bit at a time so the car doesn't stall. Then just look for white smoke anywhere from the exhaust manifold to the oxygen sensor.

Report back the results.

holmesnmanny

I take that back, I see your hydro carbons are already fairly high. I'm not always at home, using the app it doesn't show images always.

You may very well have a leak.

MAD_MIKE

Test the resistance of the plug wires if you are suspect of them.
And as for plugs Denso Iridium TTs for the HNNNNNNNNNNNNNNNNNNNNNNNNNG

faran

Thanks so much Mike and Holmes.

I am going to use seafoam technique to find the leak and was planning to take NGK Vpower or GPower plugs route.

I definitely think it's the exhaust leak causing trouble, since in 2013, car passed emissions without any trouble, at that time I did replace Spark plugs and Air filter. Since then Rack and Pinion and Headgasket has been replaced. For both, exhaust( or parts of exhaust system) has been opened.

Please see attached report for 2013 results.

faran

So I have the car up on jack stands and observed it yesterday, one of the gasket before the CAT(31378) isn't seated properly, as that part was opened for Rack and Pinion replacement.

I have highlighted in the picture, going to seat it or replace the gasket.

Also, one of the spark plug well has oil in it, seal is leaking, can it cause emission related problems or no?

MAD_MIKE

That would cause a fresh air leak and affect the O2S reading and the performance of the catalyst.

Yes. Oil even on the non firing side, can cause a misfire from grounding out the ignition lead.

faran

I am going to fix oil problem, seals. Also, I need to seat that gasket properly or buy a new one. What if I wrap muffler band-aid or something similar around that area?Would it cure the problem, you think or no? Because replacing these exhaust gaskets are a royal PITA.

MAD_MIKE

If you can assure a tight seal around the joint, sure. But it may not work.
The problem is if the gasket there is more like a ball and socket joint, allowing the engine to rotate a bit under power. If the gasket is deformed or damaged it may not seal when the engine/drivetrain is loaded.

faran

Thanks MM, I am going to work on it tonight and report back. Have already purchased the gasket.

faran

So I was able to crack the bolts for the gasket and connection between cat and middle pipe(with O2 sensor).

But pipe isn't moving at all. How on this planet earth I would pull the pipe out and take out the old gasket and add new one? Is there a trick to budge that middle pipe from Cat converter?

Also, is there a special trick to put this grommet back on the screw for valve cover, I tried it and it's a PITA. Screw has a grove on it and grommet doesn't go through it. Any tips?

MAD_MIKE

To replace the gaskets around the O2 sensor pipe, you have to remove the downpipe from the exhaust manifold.
Unbolt the three bolts to the exhaust manifold.
Unbolt the spring loaded bolts to the O2S pipe.
Unbolt the metal stand that attaches the down pipe to the back/bottom side of the engine.
Drop out down pipe.
Remove O2S pipe.
Replace all those gaskets and the two steel O rings between the manifold and the down pipe.

31633 x 2
31357 x 1
31378 x 1

As for the valve cover bolt and grommet.
Clean up the bolt so there is no grime and junk on it.
Use a some liquid detergent on the rubber portion if it is tight, gently slip the rubber over the lip, from the bottom. You will be installing the metal sheild and grommet from the threaded side of the bolt.

Lost Again

For the valve cover bolt, a piece of vac hose over the threads of the bolt....the outside of the vac hose should be right at the same size as the "shoulder" on the bolt....some oil on the vac hose and the inside of the grommet...the bad boy will slide on there with just a small amount of force

faran

You are the MAN, MM. Dish soup and elbow grease did the trick, I would have never figured it out in my entire life time. Thanks a ton for the pointer and advice.

Replaced spark plugs, cleaned all contact for Cap/Switch, spark plug tube seals, valve cover gasket and cleaned air filter(it was clean). Cleaned PCV valve too.

I used Black sealant around the gasket area, did use pretty liberal amount. I fired the car for a bit and did not see any leak around the area. Waiting for 24 hrs cure period and going to test tomorrow, will report back.

Thanks Lost Again for your tip, will keep in mind for future.

Lost Again

Glad you got them on there. Over the years I tried many ways of getting those things on the bolts. The vac hose has been my "go to" way for the last few years, it seems to provide a nice transition of size that allows the grommet to slowly expand and slip over that "shoulder" on the bolt.

faran

Black gasket actually worked and stopped any kind of exhaust leak close to O2 sensor area.

I used Seafoam today(1/3 of bottle through intake vaccum line) and noticed no smoke leak, but did notice leakage in the area where exhaust header meets exhaust manifold(pipe which has O2, Cat and eventually muffler), i-e first joint in the exhaust area.

I used lots of Red gasket in the area to stop exhaust leak, will report back tomorrow to see if I still see any leakage, else will use some more red gasket in the area and will take the car for emission test.

I am planning to use Iso-heet(Red one-Iso-Propyl alcohol) with regular gas before the emission test. Is it a good idea or not needed? Should I use Premium gas ore no?

faran

MM, just came back after the emission test and passed with flying colors.

Thanks so much for all of your help, guidance and patience.

MAD_MIKE

Would be interesting to see the numbers.