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Auto Doc: Potholes and performance tires

A car hits a pothole as it makes

A car hits a pothole as it makes a right turn from Mill Dam Road to New York Avenue in Huntington. (Feb. 7, 2011) (Credit: John Dunn)

Dear Doctor: I drive a 2011 Corvette Grand Sport with factory recommended Goodyear run-flat tires. The wheels are the standard mag wheels that come with the car. I hit potholes on two successive days. Now the car vibrates between 30 and 40 mph and between 70 and 80 mph. The Chevrolet service manager advised me over the telephone that it sounded to him that I lost a wheel weight.

I brought the car to a Goodyear tire dealer and had all four tires replaced because they were worn out. When balancing the wheels the Goodyear employee told me that all four wheels were warped. The new tires and balancing has not fixed the vibration. Is the vibration being caused by the warped wheels? Martin

Dear Martin: Welcome to the real world of potholes and low-profile performance tires. My advice to you is that you have a few choices: new factory rims, reconditioned rims from a company like Keystone, aftermarket rims from multiple companies, or new take-off rims (look online). You could also check your insurance company for possible coverage.

Dear Doctor: I bought a used 2005 Honda CR-V with cruise control. Occasionally, the cruise control shuts off. The book states that it may do this when going up or down a steep grade, but so far it only happens when driving on the flat stretch at 45 mph. Also, when the security system is set with the fob the alarm goes off for no reason. I'm told this might be a frequency problem with the lock/unlock system. Have you ever heard of these problems? Sheree

Dear Sheree: There are many built-in safety factors in today's electronics, including the cruise control system. To troubleshoot this -- and many other faults -- the technician will need to follow a trouble flow chart. The resources I use are Identifix for any recorded failures in history and Alldata for additional wiring and component location. The technician will first check for any trouble fault codes and then look up any history related to these faults. If you choose an independent shop, then make sure the technician has ASE-certification in electronics.

Dear Doctor: I own a 2008 Dodge Avenger with approximately 40,000 miles on it. The car has a quirk that my mechanic has not been able to resolve. Sometimes when I drive and then stop to sit at a light or otherwise sit and idle for a while, the engine rpm will suddenly drop below 600 and then the car computer presumably over-corrects for the low idle and then the rpm revs high. This only happens at idle with the brake on, or with the gear in park. There are no stored codes in the computer. Are there any service bulletins on this condition? Lou

Dear Lou: I looked on Identifix and Alldata and no ongoing history of the issue is reported. With no codes to help identify the problem, your next step is a road test using a professional scan tool connected. Once on the road, drive the car and observe all the input data and record it. Your technician then will compare the actual sensor information from the engine to known good signal patterns from Identifix or Alldata. A qualified technician should be able to compare the input sensor value with a correct sensor value. The fuel pressure also needs to be checked. A lazy EGR valve or intermittent vacuum leak will also cause this problem.

Dear Doctor: I own a 2006 Toyota Prius with about 50,000 miles. Up until now I have had all service done at the nearest Toyota dealer, shop. Several of the local shops have told me that they do not service hybrid cars because they do not have the special tools or training required. I was particularly upset when the Toyota shop charged me a service fee to change a taillight bulb. I had to have the bulb (that Toyota sold me) changed three times before the bulb lasted more than one day. Does your shop service hybrid cars? What do you recommend about choosing a non-dealer shop? Arthur

Dear Arthur: Most independent shops will service hybrids. The area that can be a problem is with the electric drive part of the vehicle. The "check engine" light service can also be an issue because of the complex drive system. Most independent shops do not have factory scan tools to properly scan the systems and check for problems. We do service hybrids at my shop and when help is needed we contact Identifix and/or Alldata. As for a service charge to replace a light or even wiper blade, if a flat-rate technician has to do the job then he needs to get compensated. If the service advisor does the job there would be no labor cost because the service advisor is not on a flat-rate pay as he does job. You should talk to the service advisor and tell them how you feel.

Dear Doctor: We are buying a new vehicle and in the process of checking the final price my wife discovered an additional charge called a "DOC fee." The dealer said the document fee was for administration service for writing up and processing the paper work. I checked with other dealers and they also charge a DOC fee, however the prices all vary. Is the DOC fee a normal charge? And do I have to pay for the charge? Is there a way to get around the charge? Don

Dear Don: Document fees have been around for many years. Check with your local laws on DOC fees, as they all vary. I will tell you I do not want to pay the DOC fee -- and do not. The salesman will say every one has to pay it and they cannot take it off the billing invoice. But what they can do is deduct the DOC fee amount from the sales price and leave the DOC fee on the sales form. I see this practice all the time and it is legal and you should insist on it, or go elsewhere to buy the car. -- Junior Damato, Motor Matters

Junior Damato is an ASE-certified Master Technician.

E-mail questions to info@motormatters.biz

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