Sometimes I hear it ( truck in sig) on a down shift from 3rd to 1st or 4th to 2nd. I have to let-off the gas to get it to stop.

The knock sensors are supposed to tell the pcm to retard timing,right? I never remember hearing it when it was newer. It has about 49k,new plugs and I use Sea Foam at times in the gas. It runs on 87 octane.

Are the knock sensors maybe wearing out?? Any help will be appreciated.

 

The knock sensors will pull timing but you may still be getting some knock. Maybe you got a bad tank of fuel? Do you have anyone close by that can scan for you?

 

My experience has been that the PCM doesn't always "hear" the audible knocking. One of my old oil burning engines would ping like crazy and the PCM would never register any KR.

 

I don't know anyone with a scanner;are the ones the auto parts stores use no good for this? I might have to get unlazy and learn more about this stuff and buy some type of scanner.

 

AFAIK, the PCM will only pull 8* of timing anyway, so there's still some room to ping...

 

Thanks. It has done it with different brands of gas. I've been using Valero 87 lately.

 

87 octane is for your mom's Accord.