Problems flaring up in older direct injection engines

Question: Numerous articles have been published (including yours) suggesting that direct-injection gas engines might experience drivability problems at higher mileage due to deposits building up on intake valves, and that expensive maintenance would be required to correct the issue once it occurred. Are repair shops starting to see these problems in cars built after 2010?

- B.M., Mount Prospect, Ill.

Answer: Gasoline direct-injection engines hit the streets in large numbers around 2006, and many are either out of warranty or nearly so. Yes, independent shops are beginning to see engines with problems including rough idle, a drop in fuel economy, misfires, and hard starting. The issue may be due to ethanol. Being hygroscopic, ethanol entraps water, which leads to misfires and then enters the crankcase, where it breaks down the oil additives, causing them to gas off. The oily gaseous mixture then deposits on the intake valves via the positive crankcase ventilation, or PCV, system. About all you can do is change the oil regularly and use synthetic. There are no easy solutions, including chemical solutions.

Q: My 2007 RAV4 recently had engine work done that included an oil change at a Toyota dealership. They used synthetic oil. Is Toyota switching to synthetic oil or are just the dealerships going to it? When I change my oil, can I go back to conventional oil or do I have to use synthetic oil now?

- T.B., Cortland, Ill.
A: You may freely switch back and forth with conventional and synthetic oil. But we suggest you stick with synthetic if you can afford it. There are many good reasons to do so, not the least of which are improved fuel economy and reduced engine wear.

Q: I have not one, but two 2005 Chrysler Pacifica vehicles, one with 165,000 miles and the other with 60,000 miles. My mechanic has informed me that the frames are badly rusted and that this is an issue with the Pacifica models. Have there been any recalls on these or is there any recourse for me to get Chrysler to fix these?

- A.D., Wheaton, Ill.
A: Chrysler extended the warranty period on 2004-05 Pacificas' front engine cradle to 10 years or 150,000 miles, whichever occurs first, but only on some vehicles operated in areas of high road salt usage. Illinois is included. If you already had the cradle replaced, you may seek reimbursement. Have a heart-to-heart talk with your dealership's service manager or the dealer principal.

Q: I read your column about the oil-burning Celica. I want to tell you what happened to me a few years ago with our 1997 Toyota Avalon. After having some work done on it, I started to notice blue smoke. Luckily my next-door neighbor is a great mechanic, so I ran this trouble by him. He asked me if they changed the PCV valve. Sure enough, they had. But it was the wrong valve. I went back to the shop where they installed the right valve and offered me a free oil change for my trouble. I think that this could cause trouble in many other cars, not just Toyotas. - J.H., Philadelphia
A: This is a more common mistake than you would imagine. Many PCV valves look similar but differ internally.

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