Continuing saga of friend's car failing emissions. 1992 Accord LX Sedan.

So far, my mechanic has spent last two weeks "playing with the engine" (his words, not mine!) and has done:
1. Replaced O2 sensor with known good.
Then took back off because it didn't change any numbers
2. Checked and cleaned PCV
3. "cleaned out" carb build-up
This did most good and made car pass all but the CO2 on low RPM
4. Timing belt checked and adjusted (needed slight tightening)
This made no diff in numbers
5. Air filter good
6. Replaced missing PCV breather tube (have no idea why this was gone)
7. All regular maintenance (oil/filter, plugs, etc) has been done
Owner replaced muffler when first failed a month ago

Only issue I know that has not been fixed is a small leak from hose running from top of radiator to overflow resevoir. The clamp just needs to be replaced (removed hose and inspected - OK).

Hoping someone has an idea of what the poor guy should look at next. Now he's going back to checking the catalytic converter, though he doesn't think that's the problem...

Thanks all!! Here's the Emissions report:


Saw post from 7/2009 with same issue, but ultimate solution not posted and looked like suggestion was PCV clean/replace whihc has already been done...

 

Thanks for the reply Kris.

State is Virginia - and yes, as you can see, they'll fail you for high CO2

 

If your car is at a shop, you might want to have the mechanic hook up a timing light and make sure that the timing is correct. The distributor can be rotated to fine tune the timing adjustment. Was the distributor cap and rotor replaced when the tune-up was done?

Does your check engine light come on, and are there any codes stored on the ECU?

How does the car run? Is the idle stable at ~750rpms?

Did the mechanic clean out the throttle body and both sides of the throttle plate? Clean the screen on the idle air control valve?

 

PAHonda - thank you for posting!

Don't know if mechanic did any of your suggestions, or if he's checked for codes stored in ECU. I will print your post and take it to shop in morning.

Car runs great and sounds pretty good for the year and miles (230K). No pings, no hesitation, no surging.
The engine check light does not come on.
The engine idles steady at 750 RPMs (I drove it to shop from friend's)

BUT - once and only once when engine was still cold, the idle started surging up and down bet. 750 to 2000 RPMs a few minutes after I started it and just as I began driving it up a car ramp (freaky). I turned it off and restarted and never happened again. I've emailed the owner to see if ever happened to him.

I can tell you that, based on one of your other posts, I reset the ECU by pulling the radio fuse. Just now thought of that, so noting now.

THANK YOU

 

I am not familiar with your year, but I would check to see that the vacuum advance on the distributor is working correctly. Vacuum hoses get very brittle over time and are cheap and easy to replace...good luck

What part of Va. are you from?

 

Does the 1992 accord have a vacuum advance on the distributor?

I thought that the timing was advanced electronically through the ECU.

 

Heard back from the owner - says the idle never acted funnny. Guess I can put that off to a weierd one time thing, perhaps caused by rolling it up a somewhat steep incline too soon after starting...?

Thank you again for responding!