2004 Ford Explorer engine knocking

  • 6 CYL
  • 4WD
  • 140,000 MILES
My 2004 Ford Explorer has engine knocking when you take it to 2RPM+.
I've poured the 2 bottles of solution down the gas tank and no result.
Everything else is fine - pressure, oil level, etc.

Here's the kicker - the Check Engine light hasn't come on.

Any ideas?
Do you
have the same problem?
Sunday, May 1st, 2011 AT 5:27 PM

1 Reply

Are you sure its engine knock that you are hearing? True engine knock increases with engine load not RPM. If it gets worse when you give it gas from low RPM s while in gear the its likely knocking but if it does it in neutral when you get above 2000 RPMs then I don t know what it could be. Anyway generally there are only three things that can cause knocking assuming you are using the recommended octane fuel. The first is higher than normal compression but this can only occur from either engine modifications or a huge build up of carbon in the combustion chambers. The second is the ignition timing being off but in all cars built in the past 15 or 20 years the timing is controlled by the ECU and cannot be changed. The third would be using spark plugs that are several heat ranges too hot. Also in the old days if the engine coolant was way too hot more knocking would occur but modern cars seem to be able to compensate for this. Anyway assuming you are using the correct spark plugs and the correct fuel I would say a bad sensor is causing the ECU to set the ignition timing incorrectly. Of course modern cars have knock sensors as well which should detect knocking and back off of the ignition timing accordingly so you might want to check your knock sensor as well. If any sensors are bad the ECU sould give you an error code. By the way those octane boosters sold in the auto parts stores are a waste of money and probably wont even boost your octane by one whole point.
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Sunday, May 1st, 2011 AT 9:03 PM

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