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Saturday, April 7, 2001

Mechanic Doesn't Like 'Cheap Gas'

    DEAR CAR CLINIC: Many moons ago a master mechanic advised me, "Never put cheap gas in your car." He meant only use name brands such as Texaco or Chevron.
    Does it really matter much anymore? Is there really a difference in the quality of different brands of gasoline? — C.M.G., Albuquerque
    DEAR C.M.G.: This is a controversial question. In my opinion your mechanic was absolutely correct. If you are old enough — and I think you are, applying the many moons theory — you will remember how gasoline used to smell.
    Today we burn "motor fuel." Motor fuel is a blend of hydrocarbon molecules and oxygenates and additive packages. During the refining process, salts, minerals and impurities are removed and helpful ingredients are added.
    Some companies are said to do it better than others. Some companies don't put in the expensive additives and others add "extenders" like ethanol and butane.
    In the professional repair shops we see the results of "cheap" gas. "Vapor lock" this time of year is common with warm daytime temperatures. Expensive-to-repair plugged or fouled injection system problems are much more common among those who buy fuel based on the lowest price. — Jim Maddox, Jim's Automotive Inc., Albuquerque

    DEAR CAR CLINIC: My 1987 Toyota Camry (4-cylinder with 70,000 miles) barely passed the high-speed emissions test recently. It scored high on CO and HC and elevated low-speed CO and HC.
    The car has recently replaced spark plugs; relatively new plug wires; correct timing; and an almost new air filter. I use regular gasoline containing Techron and do mostly local driving.
    Current symptoms include hard starting when cold and pinging on acceleration.
    What are the possible reasons for near failure on the emissions test? — M.M., Albuquerque
    DEAR M.M.: There are numerous possible causes for a vehicle failing the tailpipe emissions test.
    The most common things that could cause high CO and HC on your Toyota are the coolant temperature sensor (CTS), the oxygen sensor (O2S), and the catalytic converter (CAT).
    The first two are sensors that send a signal to the computer. The catalytic converter burns up the extra HC and CO before it comes out the tailpipe.
    The two sensors usually fail at a higher mileage than you have on your car. However, short drives are harder on the oxygen sensor than the coolant temperature sensor.
    Short drives are also very hard on the catalytic converter, tending to cause a buildup of carbon surfaces in the converter that deters the CAT from "lighting," or heating enough to do its job.
    My guess is it is one of these three things. Since they are all expensive, it would be best for you to have your vehicle checked by a qualified emissions technician rather than just replacing parts. If you need more help feel free to give me a call. — Jeff Albertson, Jeff's Gasoline Alley Inc., Albuquerque
    Answers in this column are provided by Albuquerque-area automotive service shops. Got a question about your car, truck, van or RV? Describe your problem (please be brief!) and fax it to (505) 823-3994 or mail it to Car Clinic, Albuquerque Journal, P.O. Drawer J, Albuquerque, NM 87103.

Copyright 2001 Albuquerque Journal Click for permission to reprint (PRC# 3.4676.297802)