Letters: Check for DTCs in surging Lucerne

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Q: Sometimes when I slow down almost to a stop and then press the gas pedal in my 2010 Buick Lucerne, it does not respond immediately and then it surges forward. This does not always happen. Two different dealers could not get it to happen. This has been happening since it was new. What do you think is the problem? — Hartini, email

A: Intermittent problems can be challenging to diagnose. Did the dealers check your car for diagnostic trouble codes? If you’re not sure, many auto parts stores will do this at no charge. And even if there are no DTCs, it doesn’t mean there can’t be a problem. Some faulty components or faulty conditions do not cause a DTC to be stored in memory.

The accelerator pedal position sensor should be carefully checked. So should the electric throttle actuator and the throttle housing.

Q: I own a 2008 Honda Accord EX with the four-cylinder engine. When my vehicle had around 32,000 miles, I heard a rattling sound coming from under the car. I didn’t notice anything unusual so I checked the oil and didn’t see any oil on the dipstick. I assumed the oil was under filled on my previous oil change and decided trying to prove that would be futile. So I added 1½ quarts of oil and went on my merry way.

After driving about 1,500 miles, I heard the rattling again. When I checked the oil, I again found no oil on the dipstick. I immediately reported this to the car dealer. After finding no oil leakage or other problems, a consumption test was started. With my most recent trip to the dealer, I had driven 1,287 miles and was down 1½ quarts of oil. The dealer advised me that with the government mandates for higher gas mileage, lower viscosity oils are being used and it’s considered normal to have up to one quart of oil consumed every 1,000 miles. Is this true?

Most everyone I have discussed this with thinks oil consumption at this rate on a low-mileage vehicle is indicative of a problem. What are your thoughts on this and do you have any suggestions for correction of this problem? — Andrea, email

A: Most manufacturers consider one quart of oil per 1,000 miles to be within the confines of normal consumption. So for your car to be considered normal, it should provide at least 1,500 miles of driving before needing 1½ quarts of oil. I would consider your car’s oil consumption to be slightly excessive.

As for the low mileage, understand that short commutes are actually harder on an engine than highway cruising. Excessive oil consumption can result from a number of issues, including a faulty PCV valve.

Another test that should be performed is to see if your engine has excessive blowby. Blowby is pressure in the crankcase caused from combustion gases bypassing the piston rings. Excessive blowby can result from worn cylinders or worn piston rings. Speaking of piston rings, the pistons’ oil control rings are designed to scrape residual oil from the cylinder walls. If they are clogged due to sludge buildup, excessive oil consumption will result.

If expensive repairs will be required to reduce your car’s oil consumption and you can’t afford it, just make sure to keep the oil level properly filled.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail ira.siegel.is@gmail.com. Siegel is an automotive instructor and an automotive service excellence-certified master auto technician.