Toyota Repair: engine ping, throttle position sensor, high mileage

Question
When accelerating at lower RPM ( foot barely pressing down on petal)my 1995 Camry with 2.2L engine pings slightly. Upon accelerating at higher RPM ( like passing on the four lane at 65mph) the pinging goes away. The car has 186,000 on it and runs fine otherwise. I usually use 89 octane and have added Gumout/Regane the last few fill ups. But it still pings. Is there a part in the engine system that helps control ping? If so, could this be the cause? Thanks so much! TG

Answer
I agree with you that you should assume that you are using sufficient octane. however, on an older engine with high mileage such as yours, sometimes you have to use a higher grade of fuel to prevent preignition as the engine gets older. On a 4 cylinder engine like yours, there is no sensor or actuator that controls "pinging". Knock sensors are only found on Toyota's V-6 and above and those are located under the intake manifold. In any case, that doesn't apply to your engine.

The only other possibility is to test your TPS (throttle position sensor) This sensor controls your injector "pulse width" and advances the timing as you press down the gas pedal to accelerate. Your TCCS throttle position sensor should show smooth increase of voltage from .5-4.5v of power when it's tested. These need to be tested using a DMM (digital multi-meter). The entire TCCS system operates on 0-5 volts. If it's faulty, I believe that throttle sensors are around $80 (maybe more by now) from the dealership. If the vehicle were mine, I would just try to run the higher grade of fuel and see what happens before I did anything else.

Hope this helped.