[Koan]

1996 Camry with 187,000 mi has had a persistent but occasional ignition knock. Only occurs at lower RPM, under load. Lifting off the throttle, pushing further, turning off overdrive (auto trans), or downshifting stops the knock. I sense no loss of power. Running 87 octane gas. Seems to run well other than this.

Have relocated knock sensor, not throwing any knock code. Just started with firewall O2 pre-heater code, but was knocking prior to that. That is the only CEL code.

Last time I changed plugs I had one with little metal balls on center electrode (it has been a while - maybe 70k miles). It was the middle plug against the firewall.

I thought the knock sensor would dial back the timing advance to prevent the pre-ignition. Are there conditions where the advance would not be retarded by the knock sensor circuit such as leaning out too much or bad plugs?

Would appreciate any insight on diagnosis. Thank you.

 

[Chris Crash]

If you relocated the sensor, it won't sense the knock as easily hence it won't retard the timing. However, if you're knocking, that's another issue that you should be worried about. You say you sense no less in power, but it's there I promise. Plugs could be the problem . What are you running? I'd replace those with some NGK Iridium as the first step.

 

[Koan]

Chris - Thank you for the reply. I will replace the plugs and go from there. You prefer the Iridium NGKs over the stock OEM

platinum plugs?