Hello I failed my smog test and I live in California, and I recently bought a new catalic converter and it helped on all the emissions except for the NO test at 25mph. Some of the results. HC was 3 @15mph and 2 @ 25mph, pass on Both. CO test was 00 on 15mph and. 01 @25. Both passed. NO @ 15mph passed read 1. Buy once he went to 25mph. The max is 730, average is 139, I tested 1073!!! I failed by alot! Idk why it has a new cat, spark plugs and wires that are like 1 year old, new timing belt, and my car has 226k miles and sounds healthy... Any idea why?? Please help!!

 

Did he wait to warm up the enigine/cat? A cold converter is inefficient

 

We don't have emissions testing here, so I'm not exactly an expert in these matters. With that said, it sounds to me like you have an EGR problem. I would expect to see a code for insufficient flow (sorry, I don't know the OBD1 number), or even a misfire. The EGR passages tend to clog on one, two, or three intake runners, so all of the EGR flow goes to the remaining cylinder/cylinders, causing it/them to misfire. This usually happens, by the way, around 20-40 mph.

 

90-95 OBDI cars do not monitor EGR flow, only EGR solenoid valve lift.
EazyMartin as stevenbr549 mentioned more than likely your EGR manifold is clogged, not allowing EGR to flow. You may or may not notice a slight tremble or ping at part throttle. ~2K rpm.

Look at the Accord FAQ at the top of the page and look for the procedure on how to clean the EGR manifold and ports on the intake runners. Fairly simple to do. Do not use Sillicone sprays to reassemble the fuel rails. Sillicone will coat and 'kill' a catalyst. Use grease to reassemble.

 

Sorry, I'm really rusty on OBD1. I totally forgot about the limitations of EGR monitoring on the old-school stuff.

 

Change the oil if it isn't fresh, new air filter, also, check the pcv valve, and finally if that doesn't work and u need to just get it passed, try a few ounces of pure 100% acetone in your fuel before you fill up, about 1.5-3oz/10 gal. If your not comfortable with doing that, that's fine, I only share because it worked for me and my car is still fine years later

 

Sounds like one of more of the EGR ports are clogged. Search Google for DIY for cleaning them out,it is fairly simple and a very common fault.....