Engine pings and has a surging idle on warm start up

Alden12 said:

I also noticed something today. When My intake was changed out, the plugs were as well because 2 of them were cracked. (I replaced them earlier within the year) All the plugs were covered in non-shiny black soot which if i’m not wrong would signify a rich condition. plus also smelling the exhaust fumes. I’m just super lost as to how the car is running rich but also pinging with lower octane gas. Pinging usually means the car is running lean.

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That is an incorrect answer.

Excess fuel tends to cool the combustion process but it won't stop preignition due to hot spots in the combustion chamber or excessive spark advance.


See http://www.onestopauto.com/What-causes-spark-knock.html for an excellent description of the causes of pinging AKA "spark knock"

Alden12 said:

Are you led to believe this is pre-ignition or Detonation then?

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Pinging or spark knock is not the same as detonation.
Pinging is preignition of the fuel air charge by some source of ignition other than the spark plug. The source of the ignition can be a hot spot in the combustion chamber such as carbon, a spark plug insulator, side electrode, or a sharp edge on a valve. It occurs before the spark plug can fire and while the piston is still on its upward movement towards TDC. That is the cause of the characteristic ping or ringing sound, much like shaking a coffee can full of BB’s.

Pinging is caused by a number of things:
1.) Hot spots in the combustion chamber such as carbon deposits from high mileage or excessive oil consumption.
2.) Wrong heat range on the plugs.
3.) Too much initial spark advance.
4.) Too low an octane rating for the engine setup.
5.) Lean fuel mixture.

Lean fuel mixture breaks out into several sub categories:
A. Vacuum leaks
B. Air entering the intake without passing through the MAF
C. Failure of the MAF, BAP/MAP (Baro or Manifold Air Pressure, same sensor, different name), ACT (air charge temp), or ECT (engine coolant temp). These should set a code in the computer.
D. Leaking exhaust gases from EGR valve at WOT.
E. Clogged fuel injectors.
F. Fuel injector wiring problems causing injector not to deliver rated flow.

6.) Computer problems: (computer problems are not common like sensor problems).
A. ROM has bad data in fuel or timing table. This should also set a code in the computer.
B. Failure of one or more of the computer's driver transistors for the fuel injectors. No code set on this one.

7.) EGR not opening at cruse power. The computer adds timing advance to compensate for the slower burning speed of the EGR diluted intake charge.

Detonation is the uncontrolled explosion of the fuel air charge after the spark plug fires and starts to burn. In a properly running engine, the spark plug ignites the fuel air charge and it burns slowly and evenly across the combustion chamber, much like a fire as it burns its way across a grassy field. When detonation occurs, the ignited fuel air charge causes an increase in the combustion chamber pressure and temperature. The remaining fuel air charge that has not been burned self–ignites explosively causing tremendous heat and pressure. The source of secondary ignition can be the same as preignition, or can be simply due to the heat and pressure. Detonation is what damages engine parts because of the excessive heat and pressure.
Detonation can lead to pinging, and the results are the same: engine damage because of the excessive heat and pressure