Engine Noise- Pinging 07 Camry Hybrid

[wnorman]

Last summer, I started hearing pinging (~25000 miles). It happens when the engine is warm. Somewhere between just above idle, under light load. I hear it mostly in frequent stop/go with top speed in range of about 20-25mph, when road noise is low. Some indication of this at highway speeds under same sort of engine load.

Worst when weather is also warm.

Moble1 oil since first change. Top Tier gasoline since day-1 (see http://www.toptiergas.com)

One bottle of Techron Concentrate made no difference.

[GeorgiaHybrid]

wnorman,

This might sound crazy but modern cars can "learn" driving habits and modify the timing and other parameters of the engine management system to increase the efficiency of the engine. It becomes a little too aggressive at times and can increase the timing to the point that “pinging” occurs. Try disconnecting the 12 volt negative terminal on the auxiliary battery located in the trunk. Re-connect after 10 minutes or so and then start the engine and let it idle (must be cold to do this or it will shut itself off) for 5 minutes to let the system reset to stock (default) parameters and relearn its idle settings.

This has worked for several others and it only takes 20 minutes total of your time. If it works, great, if not, you haven’t lost anything but a little time and effort (only one nut to loosen and then tighten).

There are several other items that can cause the problem (spark plugs breaking down under load, bad plug wires, bad sensors, etc.) but most of them will throw a MIL code. The one that won’t give you a code is carbon buildup in the combustion chambers. If you drive short trips and the engine never warms up enough to burn these deposits off, this might be the problem. That issue can be solved with seafoam.