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Engine Misfire Code Needs Reading When Cold

By Junior Damato, March 31st, 2012

strong>Dear Doctor: I own a 2004 Cadillac DeVille with the Northstar V-8 engine with 43,000 miles. When the engine is cold and at idle I get a misfire in cylinder #3, but no codes. As soon as the engine warms up, the car runs great. I cleaned the fuel injectors, the fuel rails and put in new plugs. I also added a couple of cans of seafoam cleaner in the fuel tank and have tried premium fuel. Can you help me? Dale

Manufacturer photo: 2004 Cadillac DeVille
Manufacturer photo: 2004 Cadillac DeVille

strong>Dear Dale: The first step is to check for engine data when started cold. The most common faults are vacuum leaks, especially at the rubber intake throttle body. I looked on both Alldata and Identifix sites, which have a detailed trouble tree to follow. A qualified technician will be able to read the actual engine data, particularly the oxygen sensor and mass airflow sensor.

strong>Dear Doctor: I purchased a 2010 Honda Insight hybrid vehicle. For the first month it ran fine, averaging around 43 mpg. The car shut off while I was driving one morning, leaving me in a pretty bad situation -- no power brakes and no power steering -- and no power to avoid oncoming cars. It has been at the Honda dealer for a couple of weeks and they have been unable to find what caused the problem. It has been running fine and they still have the car. I also found out that the used car dealership had the same problem before they sold me the car. What would you advise me to do? Tony

strong>Dear Tony: This problem is going to require the help of Honda's U.S. headquarters in California, not the local dealer. The drive system and all related systems in your Insight are very complex. If there are no fault codes and no history of other vehicles having a similar problem, then Honda test equipment will need to be connected to the car and the vehicle systems will need to be monitored. I did check our Identifix and Alldata tech support sites and neither had any history.

strong>Dear Doctor: I have a 2004 Mercury Mountaineer AWD with the V-6 engine and 90,000 miles. When I get my oil changed at a fast-change place they keep recommending I have both the front and rear differential fluid changed. Is this necessary? At what interval should I have the fluid changed? David

strong>Dear David: At 90,000 miles, yes, it is a good idea to change the driveline fluids. What the shop should suggest -- and is the most important -- is the transfer case fluid. This is often overlooked because of the lack of education of the workers at many fast oil change shops, which is the fault of management, not the workers.

strong>Dear Doctor: I own a 2000 Ford F-350 with 88,000 miles. My brake pedal went nearly to the floor and the brake fluid leaked out. My mechanic said that the brake lines were rotted and that all I needed was a replacement. Is this normal wear? Steve

strong>Dear Steve: I see many vehicles that have rotted brake and gas lines mostly due from poor quality metal lines that a lot of manufactures use. There are some very good quality coated aftermarket lines that most auto parts stores carry. This is what we use. Ford does offer a line replacement with both the steel line and flex line together, especially used for the rear brakes when equipped with disc brakes.

strong>Dear Doctor: What are your thoughts on the 2012 Porsche Cayenne Hybrid vs. either the conventional V-6 or V-8 version? Martin

strong>Dear Martin: No matter which Cayenne model you go for these Porsche vehicles are all very well built and well equipped. I spent a few days in a 2012 Cayenne Hybrid and can tell you that it was one of the smoothest hybrid vehicles I have driven to date. The Cayenne has plenty of power. Coupled to an 8-speed transmission this SUV has power at all speeds and under all conditions. The cockpit electronics take a bit to get used to, though. My test Cayenne had a base price of $69,000. Gas mileage was in the low 20s combined driving. I personally do like the V-8 version for the performance and twin turbo at 500-plus smooth horsepower.

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