what is detonation?
Senior Member
Joined: Aug 1999
Posts: 1,506
Likes: 0
From: Bakersfield, CA, USA
Detonation is also known as pre-ignition. That means the fuel charge in the cylinder is igniting before it is supposed to. This is really hard on the engine, because the pre-ignition is trying to send the piston back down while the crankshaft is still trying to push it up.
What causes it? A couple of things. Pressure and heat can make the charge ignite earlier, and this is likely to happen under a heavy load, like when lugging the engine - accelerating from low rpm up a hill could cause detonation in an engine that doesn't ping normally.
Low octane or bad fuel is easier to ignite than high octane fuel, so it is more prone to pre-ignition.
If the timing is too far advanced (the spark plugs go off sooner than they should), this will cause detonation.
A super-heated piece of metal or carbon in the combustion chamber, on the top of the piston, the spark plug or a cracked valve can cause the fuel charge to ignite.
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1999 XLT S/C, 4.2 V-6, auto, 3.55 rear, dark torreador red/harvest gold, bed liner, Sony 10 disc CD, Edelbrock IAS, K&N filter, Superchip, Airaid FIPK. On Back Order - Steeda Rear Anti Sway Bar, polyurethane front sway bar bushings
What causes it? A couple of things. Pressure and heat can make the charge ignite earlier, and this is likely to happen under a heavy load, like when lugging the engine - accelerating from low rpm up a hill could cause detonation in an engine that doesn't ping normally.
Low octane or bad fuel is easier to ignite than high octane fuel, so it is more prone to pre-ignition.
If the timing is too far advanced (the spark plugs go off sooner than they should), this will cause detonation.
A super-heated piece of metal or carbon in the combustion chamber, on the top of the piston, the spark plug or a cracked valve can cause the fuel charge to ignite.
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1999 XLT S/C, 4.2 V-6, auto, 3.55 rear, dark torreador red/harvest gold, bed liner, Sony 10 disc CD, Edelbrock IAS, K&N filter, Superchip, Airaid FIPK. On Back Order - Steeda Rear Anti Sway Bar, polyurethane front sway bar bushings
Technical Article Contributor
Joined: Dec 1997
Posts: 9,417
Likes: 11
From: Windsor,Ontario,Canada
Check out what I posted in this thread. https://www.f150online.com/f150board...ML/001478.html
It will explain all about it.
Regards
Jean Marc Chartier
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00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks,
Borla Cat Back
Modified Air Cleaner Outlet Tube
and air box, K&N air filter,
Superchips
It will explain all about it.
Regards
Jean Marc Chartier
------------------
00 F-150 XLT SC Flairside 4x4 4.6 w/5spd 3.55LSD
Warn XD9000i, skid plates, Draw tite class III,
Rancho RSX Reflex shocks,
Borla Cat Back
Modified Air Cleaner Outlet Tube
and air box, K&N air filter,
Superchips