For the first time in the 23 years we've owned our trusty Camry, it has failed the California emissions check. I'd like to fix it myself, but I don't know where to start. I'm hoping some of the fine people here might be able to help.

Here are the details of the smog check:

The NO output is fine.

It passed the HC check, although it was very close to being out of range on the 15 mph test (84 ppm, with 85 ppm being the maximum allowable).

It failed the 25 mph CO% test, and almost failed the 15 mph CO test. (At 15 mph, 0.53 measure and 0.54 allowed. At 25 mph, 0.56 measured and 0.45 allowed.)

The cars runs pretty well - at least as well as it has in the past five years. It has gotten a bit sluggish overtime. It is regularly maintained (it got a new starter and fuel pump in the past year). It does leak some oil, but other than that, there's nothing obviously wrong with it.

So where should I start? What should I look for?

 

My 94 V-6 barely passed recently (California). I had the plugs changed about 8 months ago. The test station guy advised me next time to get it out the freeway and give the engine a high-speed flush.

And to bring it to the test station hot. Those things (along with plugs) make a big difference. My problem is that I only put 2500 miles a year on the car, and it is all stop-and-go driving.

 

Another thought. My mechanic suggested to me that my Throttle Body would benefit from being removed and thoroughly cleaned. My Camry is 17 years old.

I guess another aggressive action would be to replace all the fuel injectors. On an '89, they must be quite dirty. Though it is possible that a few cans of that injector flush compound added to the gas tank might do the trick.

The problem is, how do you know?

 

it would cost much if you replace it, why not cleaning it?

 

Thanks for the suggestions.

In my first post I should have mentioned that I drove the car around for a half hour before taking it to get smogged. And I made sure to do some "spirited" driving. The engine was definitely hot and at operating temperature. And yet, it failed.

Also, at the suggestion of some on this forum, I thoroughly cleaned out the throttle body with Seafoam in the last year. (Actually, I did it twice.) So I don't think gunk in the throttle body is the problem either.

Any other thoughts?

 

Can you post the emissions results? numbers? This will indicate the problems areas and possible fixes.

 

Good news, the car now passes smog - but it wasn't easy to get it to pass.

The O2 sensor, plugs, wires, and distributor cap were replaced. The EGR and throttle body were cleaned. We did an oil change and replaced the oil filer and air filter. And after all that, it still failed.

Finally we replaced the catalytic converter. Only then it it pass.

The original emissions numbers are in the first post of the thread. Here are the numbers now:

HC at 15 mph: measured 44 ppm (max allowed: 85).
HC at 25 mph: measured 28 ppm (max allowed: 67).

CO at 15 mph: measured .50% (max allowed: .54).
CO at 25 mph: measured .24% (max allowed: .45).

NO at 15 mph: measured 4 ppm (max allowed 565).
NO at 25 mph: measured 5 ppm (max allowed 522).

Thanks for all your help.