Hi, I have a 1997 Civic LX and I just failed a smog test in California due to high NO levels (487ppm max, 571 measured). I've been scouring around trying to figure out the cause of this, and most people recommend cleaning/replacing the EGR valve. However, I don't think I have one on this car. I've looked under the hood and do not see anything that resembles the ones I've seen. Also, I have the 1996-2000 repair manual, and it only lists an EGR valve on engine type D16Y5, and I have a D16Y7. Does anyone have suggestions on what I can do to lower my NO output?

 

You are correct that you don't have an EGR system.

Is the CEL ON?

Some possibilities:

-Bad cat
-Engine is running too lean (check O2 sensor and fuel pressure)
-Engine is running too hot (check thermostat and temperature sensor)

 

No CEL. I scanned anyways and it didn't find anything. I just replaced the primary O2 sensor. I had my car repaired for something else, and they tested both sensors and told me they were fine. However, the secondary has not been replaced for the life of the car (over 170k).

I'll try checking those others. Thanks.

 

replace the cat. i have a hell of a time figuring out why i kept failing me e-tests. my numbers were so high. the thing was i put a new cat on when i did my exhaust last year. replaced my cat and numbers were much better. do they put it on the dyno when they run the test? tell them to leave it in neutral and run the test.

 

Well, I was counting on the California state program that helps pay for part of smog repairs if you fail, but the state has cut the program due to budget problems. I cannot afford a new cat right now, especially since the only california ones I've found were $400+. I've read some posts about seafoam to pass smog tests. Will this work for my case?

Oh, and Method, I didn't watch them do the test so I'm not sure how he tested it.

 

are cats that expensive down there?? i bought a magnaflow 3" in and out cat for 75$

 

So I ran some Sea Foam through the brake booster tube and cleaned out some of the engine. I re-ran the smog test today and passed (NOx down to 250 now). However, the smog guy ran it with a big fan cooling the engine off. He told me he thinks my radiator may be bad because the engine is running very hot. So the good news is I don't have to buy a new cat (which I can only find for $420), but the bad news is I'm not sure how long I can run like this.

 

Before messing with the radiator, you may want replace the thermostat (inexpensive) and then bleed the cooling system of possible trapped air.

By the way, does the radiator fan run when the engine is hot?

 

Thanks for the tips. I'll try that this week when I get time and let you know the results.