Are Arizona emissions tests bogus?, test history makes me wonder... Options

[914GT]

I was bored with work and I was curious how the emissions test results compared going back over the years on one of my cars. I kept almost all the inspection results for an Acura Legend that I bought new in 1987. My daughter has been drivng this car the past few years, and I still maintain it. I picked this car as I know its history and I always maintained it well. Basically the 2.5L engine has had little done to it over the years, plug changes a couple times. Replaced and/or cleaned the injectors a couple of times. The usual routine filters, etc. It's never failed emissions. I replaced an O2 sensor once because the engine service light came on.

I don't see any rhyme or reason to the numbers. We'll see how it does next month when it's due. There are some screwy variations over the years that I can't correlate to any particular repair or maintenance item. Makes me suspicious of the whole thing. I'd expect some variation due to the car and testers (all at the same location) but there are some years that are drastically different.

[Allan]

Got some major swings showing. Especially in '92 and '95. Could it be fuel related? Same brand, grade location, etc?

[bondo]

Engine temperature has a major effect on emissions. Do they do the 1 minute at 2500 warmup thing in AZ? If not it could just be how long you had to wait to get it done affecting your numbers.

[914GT]

QUOTE (Headrage @ Jul 15 2005, 10:10 AM)

Got some major swings showing. Especially in '92 and '95. Could it be fuel related? Same brand, grade location, etc?

I suppose it could be fuel related, maybe a bad batch of gas in the tank at that time.

[914GT]

QUOTE (bondo @ Jul 15 2005, 10:13 AM)

Engine temperature has a major effect on emissions. Do they do the 1 minute at 2500 warmup thing in AZ? If not it could just be how long you had to wait to get it done affecting your numbers.

That's another factor. Seems like everytime I take it I have to wait in line for about 15-20 minutes in the heat.

[MoveQik]

Interesting. Who knows? (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

A few years ago I was kicking around they idea of putting a 6 in my car(this was before I realized I would have been in WAY over my head) Any ways, my car being a 75, I assumed that there would be emmissions issues. So in my due diligence I called the DMV and started asking questions about what I would need to do to make it pass. They weren't really sure and suggetsed that I go talk to the superviser at the inspection station since he would have the info right in front of him. So I did. He fumbled around through the books and started giving me several half-assed answers. Basically no resolution. He had no clue. I went back a few weeks later after talking to some local shops and getting more info. This time there was a different guy. He had no idea either. He gave me a completely different set of answers.

Based on my experience there, I am convinced that if the numbers pass on their machines they would have no idea if the proper cats were installed, proper fuel system or anything. They would look at their charts and say, off you go! I say this because last time I went there they asked me to pop the front hood. I do so assuming they are checking the tank/gas cap...who knows. Then they guy says, "Oh yeah, I forgot the engine is in the back" Off he goes. I watch him for a second and finally pop the deck lid. "Thats cool. You have two trunks!" Idiot (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

[914GT]

Last year when I took my V8 car over I expected the worst. Figured they'd be scrutinizing the thing to try to gig me on it. They just said, 'nice car'. I opened the engine lid for them and they looked at it and scratched their heads. That was it. Pulled onto the dyno for quick idle test, passed, and was out of there in 5 minutes.

[ArtechnikA]

if it's a regular-gas car, i'd guess '95 was the year you put in premium ...

[MarkV]

Maybe in 95 you went through right after me. My car puts out 400+ ppm in HC, stand behind it & your eyes will start burning. It took the test machine a while to clear it's lungs. (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

[914GT]

QUOTE (MarkV @ Jul 15 2005, 10:46 AM)

Maybe in 95 you went through right after me. My car puts out 400+ ppm in HC, stand behind it & your eyes will start burning. It took the test machine a while to clear it's lungs. (IMG:http://www.914world.com/bbs2/html/emoticons/screwy.gif)

So it's your fault Mark! (IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) But next time with that rebuilt engine, they won't measure anything right??

[lapuwali]

Engine, and in particular CATALYST temperatures can make a huge difference to measured HC. If the engine is fully warmed up, the numbers will be lower. If the cat is allowed to cool much before the reading, it will be higher. If you pull into a station and measure the the exhaust just after a lengthy high rpm run on the freeway, you'll get much lower numbers than if you test a minute or two after letting the car sit for 4-6 hours.

Differences in the gas analyzer used, or how it's used, will also show variations. The standards are actually pretty high compared to what the "average" car produces, largely to account for variations in testing from equipment calibration, operator error, and test conditions. The standard for '87 is 220ppm, but you're getting under 10ppm most of the time. I've typically seen 10-30ppm on cars with a cat, and 150-200 on well-tuned cars w/o a cat.

Ask any experimental scientist (or better yet, one of their grad students) how difficult it is to get accurate measurements even with lots of care and training. The variations are really only 2-3x, for the most part. Getting results that GOOD in the usual environment of a smog testing station is pretty remarkable. Note that you could still pass if the test was no more accurate than a 10-20x variation.

[gklinger]

QUOTE

Based on my experience there, I am convinced that if the numbers pass on their machines they would have no idea if the proper cats were installed, proper fuel system or anything. They would look at their charts and say, off you go! I say this because last time I went there they asked me to pop the front hood. I do so assuming they are checking the tank/gas cap...who knows. Then they guy says, "Oh yeah, I forgot the engine is in the back" Off he goes. I watch him for a second and finally pop the deck lid. "Thats cool. You have two trunks!" Idiot

The reason the emission stooges in AZ work there is cuz they couldn't pass muster to work at McDonald's. It's a good thing they don't do a visual inspection like in CA, they'd have to raise the bar for employment too high...

[lapuwali]

QUOTE (gklinger @ Jul 15 2005, 10:07 AM)

QUOTE Based on my experience there, I am convinced that if the numbers pass on their machines they would have no idea if the proper cats were installed, proper fuel system or anything. They would look at their charts and say, off you go! I say this because last time I went there they asked me to pop the front hood. I do so assuming they are checking the tank/gas cap...who knows. Then they guy says, "Oh yeah, I forgot the engine is in the back" Off he goes. I watch him for a second and finally pop the deck lid. "Thats cool. You have two trunks!" Idiot   The reason the emission stooges in AZ work there is cuz they couldn't pass muster to work at McDonald's. It's a good thing they don't do a visual inspection like in CA, they'd have to raise the bar for employment too high...

The way the visual inspection works in CA is there's a list printed for EACH make/model of car as part of the testing routine. It will list things like: EGR, air pump, fuel injection. The tech simply has to look to see if you have an EGR, an air pump, and FI. Whether the FI is stock or not is irrelevant. It's supposed to be illegal (w/o a CARB exemption number), but as long as you spent a bit of time to make it look reasonably stock, you're fine. They also don't test to see if the air pump WORKS, only that it's on the car.

In practice, as long as the car doesn't look wildly non-stock (lots of chrome and red and blue braided lines everywhere), most techs aren't going to give the engine a second glance, even if you substitute carbs for EFI (and are still under the tailpipe limit). This goes double if the car is "unusual", like a 914.