I've been working through Toyota Customer Assistance to figure out this ticking (possibly pinging?) noise coming from the engine of my '01 Celica when it is COLD. The dealer insists it isn't the valves and it has to do with the fuel. He has my using the next higher octane (89) for a few tanks to see if that helps the problem. After one tank, no change. But, of everything I've read, engine ping happens when an engine is hot, not when it's cold. Is that true? When the engine warms up, it sounds fine. Any suggestions or insights are appreciated.