I have been chasing some pinging in my truck lately. It is probably very light and not detramental, as most everyone I've had listen doesn't hear it. It still is important to me, though. The truck is a 99 5.4 with 60K miles. It has new plugs, a clean throttle body, EGR, MAF, and IAC. I just finished cleaning the above mentioned things, and to my surprise, nothing was really that dirty. A little buildup, yes, but nothing that at all restricted any air flow. What is the next step now? It pings quite a bit more on 87 octane than 93, but I know that it shouldn't need premium. So, where do I go from here?
Thanks for any input
Brian

 

Clean air filter?
Pull codes. See if anything shows up. It could be as simple as an O2 sensor that is starting to go bad. Try a different brand of gas also. Sometimes the gas you think your buying isn't what it is labeled.

Good luck.....

 

Air filter is clean. If an o2 sensor was on its way out, wouldn't the symptoms be stumbling and poor idling, etc...? I can't imagine how an o2 sensor would cause pre-ignition. Could someone burn me a chip that would slightly retard the timing at certain RPM, yet still yield a performance increase?

 

At 60k, the combustion chambers may have accumulated carbon causing hot spots that tend to take some control away from the spark plugs.
It's hard to prove and only can be delt with by removing the heads for cleaning or possible use of certain fuel additives that may clean up the carbon enough to stop it..
Most engines burn very clean over there average life but some may pass enough oil to cause this carbon accumulation.
Other reasons can be the gas used had some additive or oil used caused deposits.

A lean fuel mix could also add to this. Causes of lean fuel are Mass Air meter, air leak, Ox sensors, fuel pressure on the low side.
Since you feel the higher octane seems to reduce the tendency, I lean toward one or more of the above. Reason; it slows combustion speed to a sleightly later time.
Ping is the ignition of the fuel a bit to early before piston top dead center on the compression/ignition cycle that case the heads, pistons and block to ring (ping) a small amount because to cylinder pressure peaks to early near top center when the piston/rod/crank are in 'near' vertical alignment and can't go any where in fast response to the combustion pressure developed..
Tough call I know.

I'm not telling you it 'is' any of these things but could be.

 

I was leaning towards the accumulation of carbon in the combustion chambers until I saw how clean the throttle body and EGR ports were. Everyone seems to complain that their EGR ports( only one port in my case) are clogged enought to severely restric air flow. Mine was a little cruddy, but in no way restricting any airflow. If this circuit is clean, it leads me to believe that the piston crowns, valves, heads, etc are all more than likely not sverely carboned up. It seems I have eliminated everything simple and anything beyond what I have done simply wouldn't be cost effective. I just wonder if I am missing something...

 

How about the cooling system. Pre ign. can be a prob. with the engine running a little hot. Have heard that the gauges only monitor major changes in temp. Might be running a little hot and you might not know it