Questions and answers from the ‘Car Doctor’
Q. I have both seen this device advertised for sale and supposed positive reviews of the EcoPlus. It is a plug-in device that is supposed to assist with better gas mileage. My gut feeling is that it’s another waste of time and cash, but I thought that I would send this your way for confirmation.
A. I have not tested this device, but like many over the years there are a few red flags that stand out. The biggest is that they ask the driver to carefully measure your vehicle’s fuel economy after installation for the next 150 miles. It has been my experience that after any fuel saving device is installed drivers are easier on the gas, and don’t speed. These two things alone can improve fuel economy. The second thing is, according to their website fuel economy and torque can be improved by 12 and 25 percent. All for as little as $10. Vehicle engineers literally put cars on “gram diets” to reduce weight and save fuel. If it worked wouldn’t every vehicle manufacturer build this into their vehicles?
Q. I have a 2006 Chrysler Pacifica, with 90,000 miles on it. It has been great. But like me at age 83 it is old and the subframe is rotting. The issue is, the part is no longer available, but my mechanic is looking for it, hoping to find one. The mechanic said if he finds one my car will last me a few more years and by that time I may be using Uber. Should I give up on this car and start looking for a new car?
A. This rusting issue was very common with this model and year Chrysler. You might find a specialty welding shop that can safely patch and reinforce the frame. I did look online (eBay Motors) and found several subframes for sale that appeared to look almost new.
Q. I have a problem with my BMW M3. It has 190,000 miles and is still great to drive. However, for the past five years or so the warning light comes on and codes to engine misfire for cylinders 1, 4 or 5. The cylinder identified varies. Actually,
there is no misfire that can be felt or detected, and the car runs beautifully. I have had the spark plugs and coil packs changed; the codes cleared. Bottom line: sooner or later the light comes on and I can’t pass inspection until the computer is “ready”. This takes longer and longer, used to be 50 miles, then 100, lately even 150 miles is not enough driving. I love this car; I’ve had it since new. I’m retired and don’t want to a new car. Any ideas?
A. I suspect there is some sort of vacuum leak causing a random lean misfire. This could be due to deteriorated vacuum hoses, or a leaking intake manifold. At this point the best thing to do would have a “smoke” test performed. In this test a technician pumps synthetic smoke into the engine and looks for where the smoke is escaping. The other possibility is there is an excessive amount of carbon build up on the valves and they are not closing fully which can also cause a misfire. This carbon can sometimes be cleaned chemically and even with a type of sandblasting using walnut shells.
Q. While driving my 2005 Toyota Highlander the check engine light came on and the VSC light and the Trac off light, came on. I thought it might be a dirty wheel ABS sensor, since I have never touched the sensors in 17 years. I took it to a local auto parts store, and they came with a code P0138 which is the downstream oxygen sensor 504. The sensors go from $20 up to $200 plus, for the part. Since I will drive my car another 15 years, should I pay more for a good sensor? Also, I am a little puzzled about the dash lights. If it is a O2 sensor, why does the VSC and Trac off lights come on?
A. When it comes to engine management sensors it is best to use a quality part. I have seen some of the $20 sensors cause drivability issues. I would purchase a sensor that is better quality such as Walker, Bosch, Denso or NTK (the manufacturer of the original part). Regarding the ABS and TRAC lights, it is most likely those lights are unrelated to the oxygen sensor code, but more likely a cracked ABS tone ring.
Q. I am writing to you because I can’t get a consensus on a specific issue after searching the internet and asking friends and their mechanics. For compact import cars in the Honda, Hyundai or Nissan category, do you need to change rotors when you replace brake pads. Some mechanics claim the rotors are made too thin nowadays and can’t be cut anymore. Is it true that you can’t resurface or cut them if you want the brakes to work properly?
A. As you start to remove metal from a disc brake rotor it can’t dissipate the heat as well as it can when it was at its full thickness. Many technicians will recommend a replacement brake rotor rather that resurface the existing rotors and experience a comeback and unhappy customer with a brake vibration. In my own car when it comes time to replace the brakes, I will replace the rotors. I find I get better overall braking and it is worth the extra money (and I have been accused of being cheap) and the peace of mind.
Q. I want to buy a used Jeep. Can you let me know or advise me on what type of Jeep I should buy?
A. Jeeps are as individual as the people who drive them. Although just about any Jeep can go off-road the Wrangler, Cherokee or Grand Cherokee are best suited for that. At the bottom of my list would be the Patriot, Renegade, and Compass, these three models have in some cases seen higher than average reliability issues. If you are looking at the Wrangler, depending on the year, rust can be an issue. I would also consider joining some of the Jeep forums to get some additional insight from people who drive Jeeps.