tubbedz said:
Finally got the wife's Murano back from the dealer and paid $300 for nothing. The dealer had the "engine mechanic" diagnose the Murano. He verified the engine pinging noise. He checked for intake leaks-none. He attempted to"relearn" the idle but failed. So he reprogrammed the ECM with new software and then "relearned" the idle. Engine pinging still there. Nissan mechanic found a dent in the oil pan. He said the ping was from lack of oil because the pan was dented......BULL. If it's not the pan, he suggested a new replacement engine. Why????? So I took the Murano home and replaced the pan. Engine oil pickup was not bent or crushed. With the pan off, I looked at the crank, rods, and bearings....it was spotless, no sludge, no oil burning or oil stains. The bottom of the oil pan was also clean...no sludge, no shavings....just spotless. Called the dealer today and left a message for the mechanic on what he advises to do next. In the meantime.........anyone have any ideas???
No codes or warning lights
No pinging in Park or Neutral
No pinging at high speed or nailing it from a dead stop
Pings only at part-throttle load approx 2000rpm
92 Octane Chevron unleaded
Royal Purple synthetic oil 10w-40w
No oil consumption issues
No blue smoke out of the exhaust
Nissan oil filter
NGK platinum plugs
MAF cleaned
Throttle body cleaned
New Nissan air filter
Your issue is definitely unique and odd to say the least. Considering the following:
1) If it was your gas pedal position sensor then your issue would happen all the time. But since it only fails while in drive the gas pedal is ruled out.
2) The ECU has multiple engine management profiles stored in it that will change timing curves, fuel pulse profiles, etc depending on how you drive it. If you're driving normally it will use one profile while "gunning it" from the line it will use another. This rules out the ECU.
3) Each side of the engine has its own variable valve timing advancement system. Since you're engine works fine under "gunning it" conditions I have to rule out the variable valve timing.
4) I'm not knowledgeable as to how the knock sensor would affect this specific system. My general understanding, however, is that the knock sensor will force the ECU to retard the timing to the point where you don't knock at all. This usually results in bad MPG and HP performance.
The only thing left is the spark system and the injector system. Have you looked at how the injectors are working? My thoughts keep going back to what specific conditions have to be met in order for the failure to occur. If you are running too lean of a gas/air mixture on one or more of your cylinders you're going to get knocking. Knocking to me sounds like marbles bouncing around insie the cylinder. Maybe you have an injector that is not pulsing correctly at a specific RPM thus causing your knocking.
If your friend at Honda has the capability to read timing while running, what is the ECU doing while the knock is occuring? Do you notice it retard the timing?
