QuestionQUESTION: Hi Bill - First 5 years I owned my 2006 Murano I used the 89 octane ethanol bland gas that's available in my state which falls in- between the 87 reg and the 91 premium. No problems until this last spring when I began to notice engine ping/knocking on acceleration at low speeds (don't know why they call it that when it sounds more like a rattle) Tried switching over to premium and have now run 4 tankfuls through - no change. Also tried Chevron with Techron twice when gas tank was down to a quarter tank. Also, no change. I mentioned it to the senior service advisor at my Nissan dealership at the last oil change. He said there were no computer codes being generated and when he took it for a test drive, he didn't hear anything. When I left from the oil change, I heard it right away and continue to hear it as before. Is it damaging my engine and what should I say to the service dept. to get it resolved once and for all? We love our Murano, don't want to be damaging it, and just it to accelerate and run smoothly as it did for all these years.
ANSWER: Hi there, pinging can be caused by a number of reasons like over advanced timing, wrong heat range spark plugs, carbon deposits from fuel and or oil additives on top of the pistons, excessive engine wear and a failed anti knock sensor. When the sensor detects pinging, it sends a signal to the ECU and the ECU retards the timing. Since there is no codes indicating a bad anti knock sensor or circuit, the only thing I can think of is if you are using any fuel additives to stop doing that. Use the recommended grade of motor oil, (5W30) and no oil additives either! These additives tend to leave deposits on the pistons and spark plug electrodes. The fuel mixture entering the cylinder can ignite before the spark plug fires because of heated glowing deposits in the combustion chamber causing pinging and also causing dieseling when engine is turned off. Make sure all the engine adjustments meet the manufacturer's specifications.
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QUESTION: Bill, sorry to be a bother, but still at loss for bottom line what to do and answer to my question - is the engine ping/knocking damaging the engine? The car has only 61,000 miles on it, so plugs are factory originals. No engine codes and I haven't used any additives except for Chevron Techron which is for helping to clean out carbon deposits. The engine was pinging before I used the small can of that additive so it couldn't have caused it. I am using the recommended motor oil, there is no dieseling when engine is turned off. Soo, are you telling me to have the carbon professionally cleaned from the engine and to have dealer check engine adjustments and timing? If so, what is the safest, recommended way to clean out the carbon from the engine?
AnswerYes sir, the pinging/knocking can damage your engine. I have indicated to you all the probable causes. To clean the carbon deposits you may try some "Marvel" oil which you can add to the fuel tank and some in the motor oil. My recommendation at this point is to have an ASE certified technician in Engine Performance, to have a look at the problem. You may also try to change the gasoline brand for a while. Depending on the altitude of the area in which you live, it is recommended a higher octane fuel close to sea level and at higher altitudes, (3,000ft and up) you can use mid or standard grades. At 61,000 miles I would have replaced the spark plugs as well.
