Accord fam,
I have a 1996 Honda Accord, EX, 5spd. My Accord failed my California SMOG test twice for NO @ 15mph. Please refer to the test sheet attached.
Notes/History
1. No CEL on the dash.
2. A year ago I was able to pass smog no problem after cleaning out my EGR
3. Before my first test this year, I replaced my catalytic converter with a California compliant MagnaFlow part. (Made a huge difference for my power loss. Apparently the old cat was clogged)



After failing the first test recently, I completed the following:
1. Clean cold air intake filter
2. Run Blue Devil through the system
After running the second test (image above) my NO @ 15mph still shows high numbers.

My mechanic says my car is running lean and I probably have the wrong catalytic converter installed. I had picked up a part that an O'Reilly store rep verified would fit on my car so I hope that's not the issue.

Any help with this issue would be much appreciated.

 

I realize the thread is old and you created this quite some time ago but my 97 accord, automatic, also didn't pass smog for high NOX emissions for the 15mph run and also passes fine on the 25mph run within a couple of hundred points to the max.

It was smogged in June 2020.

In my case though, HC and CO were 0.1 in both 15mph and 25mph. Max was some arbitrary double digit number above 60 similar to yours. In my case, before the smog test, I ran two bottles of gumout regane on a single full tank of Chevron regular and ran it to a little below 1/4 tank line, then filled it up with Chevron regular and two bottles of Chevron fuel system cleaner. Ran that to halfway, then drove to the smog station. I made the mistake of shutting off the car, cooling it down during the wait. It was a 2 hour wait time.

So after the failed smog, I decided to have a buddy who was mechanically inclined help me clean out the EGR ports. All 4 port 'holes' were completely covered up with black soot 'carbon' and my buddy took a screwdriver and poked at it until the hole was clear. Then took a vacuum and sucked them all up as best he could that fell inside the 4 holes. The grooves on the top cover were also the same. Took a bit of time scrapping that stuff off with a chisel with the help of some carb cleaner. Reassembled and checked for vacuum leaks and fuel injector leaks (none found).

I believe there's a detailed guide in this forum showing you exactly what to do on that procedure. My buddy pulled the ECU fuse for 10 seconds to reset ECU so then I had to drive around until the I/M monitors 'set'. Afterwards, I decided to change out spark plugs (basic NGK copper plugs, the cheapest one), air filter, oil and oil filter, transmission fluid, coolant, get the valve cover gasket seal and spark plug well seals replaced at the same time. Then I had the throttle body and backplate sprayed down with carb cleaner and wiped that clean. Then I decided to have the air filter hose replaced as there was a huge hole on the underside that I never noticed previously when my buddy pulled that out to get to the throttle body.

After that, I ran a bottle of cataclean at 1/4 tank of gas to just touching the empty line but before low fuel light comes on. Then poured in CRC guaranteed to pass, fill it up with Chevron regular to the full line, drove on the freeway at 2700-3000rpm, alternating between that RPM range for a few days until a little below the 1/4 tank line but not yet touching the empty line. By then, a whole week had passed by, then I fill up the gas tank with Chevron premium to the full line. Again, drove on the freeway for 30 minutes at 2700-3000 rpm's then got off the Freeway and went straight to the smog station. I DID NOT turn off my car this 2nd time when I arrived. Just left it on the entire time that I had to wait. It was a 30 minute wait. Then the smog station smogged it and it pass the 15 mph run at 300 points below the max. HC and CO went up to 9 and 8, from 0.1 on the 1st attempt, respectively though. Not sure if it's related to the premium gas I put in or if it's because the EGR ports are cleared out of carbon or whether it was the back-to-back fuel system cleaners that I ran through the gas tank before the 2nd smog check attempt.

Not sure if it'll help you but that's what I did with mine. Oh yea, my catalytic converter is also a CARB-compliant magnaflow where it had to be welded on. That thing is 9 years old. Never changed out the O2 sensors since I bought the car off the 2nd owner on Craigslist. I also live in California.

By the way, after failing the first smog, the smog tech guy suggested to turn the distributor a few degrees off center from top dead center (TDC) to retard the timing a bit. The problem is, the 96 or newer models went to OBDII standards so it's controlled by the ECU and is supposedly automatically set to the ideal timing in whatever condition the car may be in.

My mechanic tried turning the distributor anyway, per the smog tech's instructions and advice. Not sure if that helped but something to note.

That's about it. Hope this helps.

 

I appreciate the long post and the advice. I'll keep this simple. I had already cleaned out my EGR, new spark plugs, oil change, cleaned CAI filter, and new Magnaflow CA compliant catalytic converter. Still failed smog.

Here's where it failed.... I needed NEW O2 Sensors! After I had these two sensors replaced, my car passed no problem!

Once again, thanks for the advice. I hope this info comes through for others.