Does pre-ignition cause detonation?
Excessive cylinder head temperature can lead to detonation, which in turn can cause catastrophic engine failure. Turbocharged engines are especially heat sensitive. The explosion of pre-ignition and detonation is like hitting the piston with a sledge hammer.
What causes detonation in a Subaru?
Anything that promotes detonation such as low octane fuel, lack of proper tuning, and prolonged hard driving can potentially cause piston ringland failure. Detonation is when the mixture auto-ignites and forms an additional flame front in the combustion chamber.
How do you fix pre detonation?
There are several ways to cure pre-ignition:
- Run higher octane fuel. Premium gas rated at 92 or 94 octane is best for an engine with a compression ratio between 9.25 and 10.25:1.
- Run the engine on the rich side.
- Try playing with ignition timing.
What causes pre-ignition knocking?
This is generally caused by some type of glowing ignition source such as a hot exhaust valve, too-hot spark plug, or carbon residue. Pre-ignition is especially damaging to engine components like pistons and head gaskets, since excessive cylinder pressures can occur even before the piston reaches top dead center (TDC).
Is pre-ignition the same as detonation?
The pressure from pre-ignition is not rapid like it is with detonation. Instead, the pressure is very high and has a much longer duration. Damage: Damage from pre-ignition is much more severe and instantaneous than that from detonation.
How do you know if you have detonation?
What Are the Symptoms of Detonation? Detonation—sometimes called knock or pre-ignition—is a pinging sound that can sometimes be heard during acceleration and throttle tip-in. Unlike normal exhaust noise, detonation is a higher-pitched, raspy note that emanates from the engine compartment.
How do I know if I have Ringland failure?
When the ringlands on your Subaru have failed, you will likely notice one of the following things: Blue smoke coming out of the exhaust. A large amount of oil being consumed very quickly.
Which Subarus have UEL headers?
Unequal Length Header The factory header for most US market turbo EJ20 / EJ25 Subarus including the WRX, STI, FXT (Forester XT), LGT (Legacy GT), Baja Turbo, and Outback XT are unequal length. This includes the current 2.5L STI, but does not include the FA20 powered WRX / FXT.
Can Cam Timing cause detonation?
Aggressive timing advance increases pressure and heat while the mixture is being compressed. This can cause the remaining mixture to detonate.
Can too much fuel cause detonation?
If the air/fuel mixture is compressed too much, it can detonate. Low coolant or a bad water pump can cause the engine to overheat.
Is detonation same as knock?
Detonation is an uncontrolled combustion event which occurs after the spark event. Pre-ignition is an uncontrolled combustion event which occurs before the spark event. Knock (pinging) is the actual noise that can be audibly heard if detonation is bad enough.
How do you test for detonation?
The best way to diagnose detonation in this situation is to install a wide-band oxygen sensor and monitor it during periods of high engine load. A lean condition under full throttle can induce knock at ratios as low as 13:1, and that should tell you not enough fuel is reaching the cylinder.