Emissions Test

Hi,
Yesterday my dad took his 98' Sienna with a 3L V6 to an emissions test. You've probably guessed already. It failed. The NOx ppm was over 2000 when the limit was 548. Its got a new cat, oil change and a new air filter. The spark plugs were changed less than a year ago along with the timing belt and water pump. Its also got a new rear o2 sensor because of the check engine light. What else can be the problem?

Do you have an exhaust leak from before the cat? I'd imagine that'd skew the readings a bit...

Is there a Service Engine light/DTC code? It will not pass if the SES light is on.

How many miles on the van?

No, there are around 160 000 miles. It might be that the computer system isn't used to the new o2 sensor yet. My dad will probably have to drive it around for about 200-300 km with octane 91 gas (at least we're trying that now).

Did you run the test with 91 octane? I assume 87 octane is what is recommended. Running higher octane than recommended can effect emissions.

Only other thing I can think of right now is that your van has a dirty fuel system. The engine might be full of carbon and gunk.

I'd recommend using some injector/fuel system cleaner. Also, take it on the highway and go wide open throttle (floor it) a few times to help push that crap out the tail pipe.

No, for the test we used 87 octane. The idea of a dirty exhaust system is a good idea. I'll ask my dad to try it.

Dirty will cause higher Hydrocarbon emissions, not NOx. NOx will be caused by the van running too lean, since the fuel trims haven't adjusted yet, since it's been running without a functional O2 sensor for quite a while.

Running it for a few hundred more kays is the right idea... let the engine relearn the fueling paramaters.

Another thing to check, if it has an air mass meter, is intake leaks after the AMM but before the cylinders. The AMM would measure X amount of air but as the result of the leak there would be more... and only fuel for the X amount. There's only so much the Lambda (O2 to the world outside LH Jetronic) sensor can do to correct the situation.

My dad just took it yesterday after running it for 300km and it passed!

Good ole LTFT (long term fuel trim). Never lets you down. Except when the O2 sensors are busted...

Side Question:

Is Michigan the only state that hasn't lost its mind, and still doesn't require emissions testing?

YSSMAN

Side Question:

Is Michigan the only state that hasn't lost its mind, and still doesn't require emissions testing?

Florida doesn't, both of my cars probably wouldn't have ever been on the road otherwise.

YSSMAN

Side Question:

Is Michigan the only state that hasn't lost its mind, and still doesn't require emissions testing?

Don't require emissions testing here in Louisiana either. I don't think a lot of Southern states have emissions testing...

Minnesota doesn't either luckily.

Man you guys are lucky...

I have a feeling that I wont be able to own a muscle car someday in CA

opendriver

Man you guys are lucky...

I have a feeling that I wont be able to own a muscle car someday in CA

For an antique you're not required to pass the same level of emissions testing. I can imagine it would still be hard to pass if everything isn't restored and is full of 30+ years worth of carbon and other build up though.

Illinois does a an OBDII test. (Tailpipe test for older cars) But no visual inspection. As long as there are no trouble codes you pass.

I know a bunch of cars that run around Illinois with all their emmissions stuff taken off that still pass the test. I'm thinking of doing the same.