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" Senior Editor Mike Allen answers readers&amp;#039; car questions. Q: My 1998 Corvette passes California smog, but it barely passes NOx at 15mph. It is good at 25 mph and all other tests look good. I am using 89 octane fuel. Will the 15 mph NOx level improve if I use 92 octane instead of 87 octane? JOHN ELLIS A: No. Check for proper EGR function, it may be partially blocked by carbon. Q: Last year the a/c compressor failed in my 1989 Caprice. I replaced it and changed the coolant to R-134a since R-12 is so expensive and hard to come by. I have noticed that the R-134a does not cool as well as the R-12. Is it possible to make my system cool more? M.W. AKERS, Sr. A: R-134a is not as effective a refrigerant as R-12, and consequently provides somewhat less cooling. My only suggestion is to make sure the airflow around the condenser isn&amp;#039;t obstructed, and to scrub all the dead bugs off the fins to improve heat rejection. Otherwise, you&amp;#039;re stuck. Q: After leaving my parking brake on for most of the winter the rear wheels of my 1988 Chevy Beretta won&amp;#039;t engage. I&amp;#039;ve been told that the cable is rusted into the On position. What should I do? MICHAEL SWEENEYA: It&amp;#039;s probably a combination fo the cable rusting and the shoes rusting to the drums. Start by getting under the car and loosening up the parking brake cable at the splitter in the center. You might be able to loosen up the shoes by rocking the car back and forth a few times. Otherwise, you&amp;#039;ll have to remove the wheels and beat on the brake drums with a hammer to loosen them up. You almost certainly should replace the shoes and turn the drums as soon as you can. Q: I have a 1988 Honda Dream 125 motorcycle that I bought used. I live in Thailand and I want to bring it back to the States. I have been told it won&amp;#039;t pass emissions inspection. Is this true? A: I&amp;#039;m pretty sure there are no emission requirements for 1988 motorcycles. Check with the EPA. And if you&amp;#039;re going to California, check with CARB. Q: I bought a new Ford F-150 4.6L, 4 x 2 Supercab. I think there is a problem with the idling of the engine but Ford does not agree. It will start up idling at 1200 rpm for about a full minute, then taper off for the next minute down to 1000 rpm. I brought this up to the dealer because I do not think it is good practice to put it in gear at a higher rpm. Am I thinking wrong on this? They told me it is computer controlled and can not (or will not) adjust it. Aren&amp;#039;t computers programmed by humans? I also drive a 2005 F-150 that will start up at 1200 rpm for about 10 seconds and then drop back to 900 rpm. All that I have read in your articles tells me that initial idling is all about oil pressure assurance, is this correct? A: The higher initial idle is for two things: First, to ensure good oil pressure immediately. And more importantly, at least from the car manufacturer&amp;#039;s viewpoint, is to heat up the catalytic converter ASAP to meet emissions regulations. It won&amp;#039;t hurt to put your car into gear before the idle comes down. In fact, when cars had carburetors with chokes, the fast-idle cam would keep the idle higher than your 1200 rpm for longer. The high initial idle is preprogrammed into the computer, and the dealer really has no way to change it.Q: I have the Popular Mechanics auto repair CD-ROMs that I bought several years ago. I tried to add more data to my GM repair file, but the source is no longer in existence. Is there another site I should go to, or do I just start over? WES A: PM, in partnership with Alldata, used to market CD-ROMS with repair info. This product has not been on the market for 6 or 7 years, but apparently there are a few still in use. Alldata now provides this repair info at: alldatadiy.com. "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.popularmechanics.com/cars/how-to/a837/3870942/>