| Texxxxx |
Sat Sep 20, 2008 1:10 pm |
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I went in today to get my Vanagon smogged. I'm in California. It failed. They said they wouldn't charge me again for the smog check if they diagnosed it and fixed it. OK...no big deal...I'll think about it...registration isn't due until the end of next month.
I started looking at the numbers on the way home:
...and noticed the huge discrepency in the HC (PPM) that failed (by a measly 4 points) vesus the the one that passed and their relation to the RPM. I went back and told them it would most likely pass if the RPM was brought up in the M1 test. I brought the idle up a bit and talked them into retesting for free.
The max RPM the machine will allow is 1100 for the M1 test. When it hits 1100 the test stops.
Notice the HC (PPM) went down more than 50% with an additional 75 RPM.
I realize these smog shops make most of their money when cars fail and they get to 'fix' them. This is just a heads up for something to look for if your van fails a smog test. |
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| glutamodo |
Sat Sep 20, 2008 2:26 pm |
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High HC's can sometimes be "fixed" by running the engine faster, but it's not really a fix, it's just a way of passing the test. VW didn't intend the idle speed to be that high. Usually an ignition tune up, making sure the spark plugs, plug wires and good and that the timing is correct, and changing the engine oil brings the HC's down. Your numbers were pretty good already though, but anything that promotes burning of hydrocarbons at lower speeds helps. The hotter the engine is, the better too.
-Andy |
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| r39o |
Sat Sep 20, 2008 10:18 pm |
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You're close. Bring the low CO up and the HC will come down. Done.
You are lucky they are not doing a rolling bed test like they do elsewhere in Cali. They measure NO then too. Most frequently a well tuned van will fail on NO. New cat fixes that most of the time.
Did you test your van VERY hot? |
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| Texxxxx |
Sun Sep 21, 2008 7:12 am |
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r39o wrote: Did you test your van VERY hot?
No, the first test was done after it had been sitting in the lot and cooled down for half an hour. The second test was done after I had left the shop, driven 10 miles, turned around and went back. Went I got back it was tested almost immediately...I took a few minutes to increase idle. The van never gets 'really hot'...or 'hot', even. I had a new radiator and hoses put in when I had a used 2.1 engine (60K) installed with new heads 6K ago.
glutamodo wrote: Usually an ignition tune up, making sure the spark plugs, plug wires and good and that the timing is correct, and changing the engine oil brings the HC's down.
All this was done with new parts 6K ago and I changed the oil last weekend. I appreciate the insights. |
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