2000 Honda Civic Engine Detonation

2000 HONDA CIVIC
170,000 MILES • 4 CYL • FWD • AUTOMATIC
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CJBROWNLEE
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Multiple issues have appeared with this car - none of them have been catastrophic, as the car has been completely reliable. They all appear to be ignition or fuel related. The only item I have not changed to this point is the MAP sensor.

I replace the spark plugs and distributor cap every 30,000 miles - the components appear melted at this milage. This was first noticed at 60,000. I have heavy engine detonation under part load and full throttle. Some days it sounds like the bottom of the engine will fall out.

I have replaced multiple O2 sensors as the OBD codes indicate I have a problem with my pre-cat sensor. When I look at the sensor readings with the vehicle running at idle, the O2 readings bounce up and down. When I look at the after-cat sensor readings, these are rock-steady.

My engine is mechanically sound when performing a cylinder pressure and leakdown check.

I have kept up with all maintenance - I am on my third timing belt. Oil changes and coolant changes have not revealed any suspicions with a blown head gasket. The car still gets 38 mpg, and starts every morning.
Oct 13, 2010 at 5:18 AM
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MHPAUTOS
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Hi there,

With engines of this age excessive carbon build up can cause predetonation, often using premium, fuel can help clean a good proportion of this carbon, what fuel do you use?

Mark (mhpautos)
Oct 13, 2010 at 5:27 AM
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RASMATAZ
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Hi cjbrownlee, Welcome to 2carpros and TY for the donation

Spark knock/pinging/detonating could be caused by an engine that's overheating, excessive combustion chamber temperature to due to non-functoning EGR valve, excessive carbon in the cylinders acting as glow plugs
Oct 13, 2010 at 5:34 AM
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CJBROWNLEE
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I will have to check/replace the EGR valve - I was not thinking about this.

This would not impact the errant readings from the pre-cat O2 sensor as well, would it?
Oct 13, 2010 at 6:25 AM
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RASMATAZ
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It shouldn't affect the pre-cat O2 sensor
Oct 13, 2010 at 6:36 AM