Pinging Tacoma

[yaakov1]

I have a 1999 tacoma 4wd 3.4l, engine pings badly, tried 91 octane no better, does not do it constantly, it has a mind of its own, any one have similar problems, I am the original owner 47,000 miles keeps getting worse, plus the dealer says its normal.

[towjo]

The pinging or predetonation is basically the combustion event occurring too soon causing the piston skirt to slap the cylinder bore. This can be caused by a number of things. Over-advanced ignition, combustion chamber deposits, compression ratio too high, and the wrong heat range plug can all cause this. A engine knock sensor is usually installed by the manufacturer to !Removed! the engine timing when predetonation occurs.

I would suspect that several conditions are present in your situation. First, combustion chamber deposits causing the knock and a faulty knock sensor allowing the event to take place. This situation is not normal and can/will cause piston damage if left unchecked. My advice is to bypass your current dealer and get a second opinion from another dealer or a competent mechanic.

If you choose to tackle this yourself, you will have to locate the sensor and replace it. Then perform a injector/upper combustion chamber cleaning. This should take care of the problem assuming everything else is okay. Calvert