zrater

seems like hot gas and high intake temps, can you tell me what causes ping and how to get rid of it. this sucks.

will62085

iTrader: (4)

ping, or aka detonation or pre-ignition, is cause by either a lean condition, which makes the air/fuel mixture combust at a lower temperature, therefore igniting too early, or it is caused by too much timing advance

Dave F

ping is also caused by carbon build-up in your combustion chambers. This is more often found in older cars. Inside your engine, little "stelagtites" of carbon can actually glow red (like a mini glow plug) causing fuel to pre-ignite. This is what causes the grinding ping in high-mileage or poorly maintained cars.

Dave

jimmyblue

iTrader: (11)

Ping, "spark knock" comes when the burn is too fast
or started too early, and peak cylinder pressure happens
before TDC. Then you have the piston trying to compress
an explosion instead of surfing ahead of it.

High flame speeds come with lean mixture, high cylinder
gas temps (hot air compressed 10:1, hot walls, etc).

For a given flame speed there is a proper advance
to maximize torque. If you ping, you're well past it.

You need to know your mixture and whether it's
proper both steady and transient. Transient mixture
on this motor is all speed density, tip-in = unsteady
MAP = speed density mode. Mods made without
tuning will jack around the speed density result.
Any worthwhile mod is aimed at improving the
breathing (VE) but if you don't model that in the
VE table(s) then the computer has no clue (other
than fuel trim learning, which is also out to lunch
on changing throttle, it seems in my observation).

The siimple answer is to pull out timing. But this is
not the best way. The best way is to fix fueling
errors as you find them and then optimize the
advance.

WS6 RULES

jimmyblue knows what he is talking about. Just to throw in another 2 cents - Preignition is a whole different thing, like the name says something other then the spark plug is causing the ignition. Has nothing to do with timing. The ping sound you hear is the shock wave hitting the piston and then bouncing back and hitting the head. That is why low octane fuel pings. It burns too fast and hits the piston like hammer and then bounces back up to the head. You want to push the piston down not hit it. High octane burns slow so this won't happen. Too much ping for too long can crack a piston.

technical

The short answer is heat.

Pre-ignition: Spark advance "increased" by excessive heat causes the fuel mixture to pre-ignite. The spark plug still fires correctly (according to the timing curve) but the heat causes an early combustion. Anything that causes extra heat can cause this: Extremely high ambient temps, higher compression ratio, lean fuel mixture.

Detonation: A hot spot in the cylinder (piston or chamber) that retains enough heat to fire the fuel mixture without the spark plug. Carbon buildup is the most popular cause, but sharp pieces of metal from machining or service cleaning can cause this as well. This is specifically why I don't recommend cleaning pistons while doing a head swap.

WS6FirebirdTA00

iTrader: (33)

ping is NOT detonation, it is spark knock though. detonation is a firing of the gasses that were unburned and when the piston is not on the way to compression and firing. jimmyblue has it though. what happens is the flame front starts from pre ignition of the air fuel mixture in the chamber, before the spark plug fires. then as the spark plug fires the fronts will meet and a HUGE pressure rise will come, all this happening before TDC. heat, fuel, spark all contribute, you dont have to worry about the heat really because the cars are designed with the proper stuff for the temps, higher compression can lead to spark knock as well

TAQuickness

iTrader: (28)

Keep in mind also, that many engines will survive moderate detonation. Pre-ignition can kill an engine within 1-2 revolutions. As a very simple basic visual, detonation occurs on the down-stroke and pre-ignition occurs on the up-stroke.

technical

What most people hear/have is pre-ignition, but detonation can make a similar sound. Though not quite as pronounced.

SSpdDmon

iTrader: (10)

See below...