Detonation
 

My 01 PT Cruiser suddenly started giving signs of detonation. Replaced Knock Sensor although no codes were indicated. 180K w timing belt replaced twice, E3 spark plugs w/maybe 20K.Tried higher octane, have used fuel injection cleaner w/every service @ 3K since new, original owner.Where do I look next? Don't understand problem w/no codes. Regularly get emission codes related to PCV hose, have to regularly tighten clamps on hose (added when first code showed). hose replaced at least twice.. I only mention this to indicate code system is functioning. HELP, need a direction to look.
THANX, Roger

What are the signs of detonation you are seeing/hearing and when are these noticed? I am not aware of any specific codes for PCV issues, are you referring to EGR codes? What specific codes had you been seeing?

The spark plugs are not correct; these motors run best on OEM champion copper, nice fat hot spark. Note there was a tsb that updated the plug specification and gap. When was the last time the spark plug wires were replaced? Should be every 60,000 miles.

Detonation
 

Normal rattle-like sounds from top of engine when loaded, like climbing hill. Can be duplicated loading engine against convertor. Codes mentioned are P0442 and P0455 EVAP Emissions control system (small/large). No codes are now present. Previously cleared Cam Sensor code w/sensor replacement.also. E3 plugs gained 1 MPG over previous Champion Copper, were replaced w/plug wires 31K ago. PT has Flowmaster exhaust and prior to latest trouble had K&N air filter. K&N media fell apart w/latest cleaning attempt, replaced w/paper.