Dear Auto Doctor: I own a 2002 Cadillac DeVille with only 66,000 miles. There is an engine knock that the dealer says is carbon buildup. He said a de-carbon treatment will cost $400. What is causing the problem? How can I prevent it?
-Bob
Dear Bob: When we have a customer with this problem we suggest the use of full synthetic oil, premium gasoline, and most importantly, brisk acceleration entering onto the freeway once a week. The carbon buildup is due to a combination of slow driving and oil deposits.
Dear Doctor: Friends are telling me that discount gas stations sell poor quality and even dirty fuel. Another friend told me there is a lack of additives in the cheap brands. Is this true?
-Mike
Dear Mike: Here’s the real deal. The off-brand gas stations can actually be the big brand names that cost much more at the name brand stations. As for dirty gasoline, not true. Dirty gasoline would come from dirty underground storage tanks. The lack of additives does have some merit. The big brand refiners have secret additive packages, and each company has its own recipe of additives. And they all claim to have the best.
Dear Doctor: I own a 2006 Hyundai Sonata V-6 with the five-speed automatic Sportronic transmission. When in the manual mode and shifting from first to second gear the transmission shift feels like it is slipping. The dealer said there is nothing they can do. There is no re-flash for the condition. I test-drove a 2009 Sonata and the transmission was very firm shifting. The dealer said if the transmission was slipping the computer would set a trouble fault code. Do you have any ideas?
-Roger
Dear Roger: Indeed, if the transmission was actually slipping enough then the computer would set a trouble fault code. The window of slippage is set up in the computer and it sounds like the slippage is not enough to set a fault code. You can try changing the transmission fluid and use only the recommended fluid. The newer vehicles have better programming and are designed for the firmer shifts.
Dear Doctor: I own a 2000 Ford Ranger V-6 with 120,000 miles. Occasionally, on some cold mornings when I start out and accelerate to 40 mph the truck will start to buck until I get up to 60 mph. I’ve replaced the spark plugs and plug wires and have added several bottles of injector cleaner. What would you suggest?
-Sal
Dear Sal: The problem most likely is the camshaft position synchronizer. Check all the basics and run full engine performance and computer tests. There could be a trouble code pending that does not set the “check engine” light.
Dear Doctor: I own a 1992 Oldsmobile Toronado. The transmission shifts hard and the engine seems to idle high. I went to a transmission shop and they did not find a problem. I went to another repair shop and they replaced the engine mounts. I still have the same condition. What do you suggest?
-Harold
Dear Harold: The first step is to run a computer scan looking for trouble fault codes, even if the “check engine” light is not on. There are many possibilities, including new computer proms. However, the engine idle speed will need to be repaired before the transmission testing can begin.
Dear Doctor: My 1998 Buick has 115,000 miles. The car screeches as I make turns. The tighter the turn the louder the screech. The local shop checked the car and could not find the problem.
-David
Dear David: The problem sounds like the serpentine belt is slipping under the load of the power steering pump. The technician can mark the belt and power steering pulley, start the engine and let it idle for 30 seconds, without touching the steering wheel, then shut the engine and check the marks. Next start the engine and turn the steering wheel until the screech is heard. Again shut the engine and check the marks. Make sure the belt is the correct size and the automatic belt tensioner spring is good. There is an adjustment mark on the automatic tensioner and it can be checked with the belt on.
• Junior Damato is an ASE-certified Master Technician. E-mail questions to info@motormatters.biz. Mail questions to: Auto Doctor, 3 Court Circle, Lakeville, MA 023 47. Listen to Junior online at www.1460wxbr.com Saturdays from 7 a.m. to 10 a.m.
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