My 92 400e (165K) just barley passed smog, the shop said it probably won't pass next time. Had trouble with the HC (PPM) Max is 105 and it measured 104, so it barely passed.

Anyone know what HC (PPM) stands for? Is there anything I should replace to remedy this? Everything else was average.

http://www.peachparts.com/shopforum/showthread.php?p=833484#post833484

You only have to smog that thing every 2 years so don't sweat it until it needs another smog test. The test only stations do not give a great test, they only test until it passes and then goes on to the next test. You will always see one area that barely passes on these cars. If you reduce the HC (hydro carbons) you will likely drive up the NOX and then that will be the item that just barely passes.

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Doug
'83 300SD "Old Gold" 170,000 mi.
'82 380SL "Green Machine" 190,000 mi.

Some days you're the pigeon, some days you're the statue... I'd rather be the pigeon!

I'd like to hear your explanation for this statement. Look at my test results in the link I previously posted.

Not only was my 15 MPH HC count down 35 percent from the previous test, but the CO reduction, averaged for both the 15 and 25 MPH tests, was about 50 percent, and NOx was reduced on the order of 90 PERCENT for both tests!

Duke