Results 1 to 7 of 7

Thread: Detonation!! Symptoms / Warning Signs

  
  1. #1
    Status
    Offline
    MrStush's Avatar
    AOC Premium Member
    Join Date
    Jul 2008
    Posts
    2,625
    Mentioned in
    1 Post(s)
    Quoted
    0 Post(s)

    Detonation!! Symptoms / Warning Signs

    Guys / Gals,

    With all the problems a few members have recently had with Detonation leading to engine damage i.e Melted / Cracked Pistons, Damaged Ring Lands etc. Can any of you Techheads give a laymans explanation of 'Engine Detonation' so that people can recognise the symptoms or warning signs in the event that they are unfortunate enough to experience this.. (We all know prevention is better than the cure!!) There are loads of members on the AOC with tuned turbo engines, and if we can save a few members prized engines by explaning the do's and don't's etc then surely it is a good thing.

    I have read some information on the net about Detonation and a lot of it seems so complexed that it went straight over my head!... (Lame excuse I know)

    Anybody??..........
    Star Silver SRI Turbo..'Red.Dot Reloaded'..Cybox Precat, Cybox Catback SS Exhaust..K&N Panel Filtered...9Ltr EDS SMIC!!.....

  2. #2
    Status
    Offline
    smarty-turbo's Avatar
    AOC Fanatic
    Join Date
    Dec 2007
    Posts
    336
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    warm up n cool dwn the engine everytime u get into it is a first start

  3. #3
    Status
    Offline
    bartonz20let's Avatar
    AOC Obsessed
    Join Date
    Feb 2008
    Posts
    1,153
    Mentioned in
    0 Post(s)
    Quoted
    3 Post(s)
    think thats more for the turbo's sake the warm up cool down.

    from wikipedia;

    Knocking (also called knock, detonation, spark knock or pinging) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. It should not be confused with pre-ignition (or preignition), as they are two separate events.
    Just Another GSi Build Thread (Big BHP Build) - Feedback Thread (Comments appreciated )

  4. #4
    Status
    Offline
    npfman's Avatar
    AOC Regular
    Join Date
    Sep 2009
    Posts
    201
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    ZLET's have knock sensors anyway dont they? When i had my car datalogged and remapped by Courtenay after a certain company remapped my car this was the only thing that stopped it from detting!

  5. #5
    Status
    Offline
    MrStush's Avatar
    AOC Premium Member
    Join Date
    Jul 2008
    Posts
    2,625
    Mentioned in
    1 Post(s)
    Quoted
    0 Post(s)
    Quote Originally Posted by bartonz20let View Post
    think thats more for the turbo's sake the warm up cool down.

    from wikipedia;

    Knocking (also called knock, detonation, spark knock or pinging) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. It should not be confused with pre-ignition (or preignition), as they are two separate events.
    Barty, cheers for that however I am looking for it to be explained in simpler terms so that everyone will be able to understand it.... I had read this definition on Wikipedia, but to be honest that info would go straight over a lot of people's heads..

    I want to know are there any tell tale signs when driving, is this something you can feel like a shudder through the engine, is it a rapid or slow sequence of pops / bangs etc..

    Some Techie should be able to explain it in lay terms...
    Star Silver SRI Turbo..'Red.Dot Reloaded'..Cybox Precat, Cybox Catback SS Exhaust..K&N Panel Filtered...9Ltr EDS SMIC!!.....

  6. #6
    Status
    Offline
    bartonz20let's Avatar
    AOC Obsessed
    Join Date
    Feb 2008
    Posts
    1,153
    Mentioned in
    0 Post(s)
    Quoted
    3 Post(s)
    From repairpal.com, bit easier to understand.... i think

    Engine knocking refers to the metallic sound an engine can produce when pressure is applied to the gas pedal. The noise may be a hollow knocking sound or more of a rattling sound—in either case, it's not a sound you want to hear.
    When an engine pings, it releases pollution into the environment in the form of nitrogen oxide (NOx) and raw, unburned hydrocarbons (HCs). These two chemicals are poisonous gases that show up as yellowish-brownish in a polluted sky. They can also cause respiratory problems like asthma and emphysema.
    Common Reasons for Engine Knocking


    Improper Combustion Process
    An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). In a properly-firing cylinder, the spark plug ignites the air/fuel mixture and a flame front starts on one side of the piston and burns across the top to the other side, which creates a rapid and evenly-expanding gas that pushes down on the top of the piston. When the air/fuel mixture is ignited prior to the spark plug firing, the two flame fronts collide, causing the pinging/knocking noise.
    Engine Is Too Hot
    An engine can ping because it is too hot. This is another uneven combustion scenario that is caused by the air-to-fuel mixture "lighting off" by itself. If the cooling system does not keep the engine's combustion chamber temperature in check, the air-to-fuel mixture will begin to spontaneously explode. This is also called "pre-ignition."
    Improper Gasoline Octane
    In addition to cooling system problems, pinging can be caused by improper gasoline octane, an overly lean air-to-fuel mixture, or a lack of proper exhaust gas recirculation. The exhaust gas recirculation system (EGR) was created to neutralize engine pinging by adding a small amount of exhaust gas to the air-to-fuel mixture going in to the combustion process, which limits the peak combustion chamber temperature.
    Internal Mechanical Problems
    Internal mechanical problems can also cause engine knocking. One such problem stems from excessive clearance inside the bearings in the connecting rods that transfer the downward movement of the pistons to crankshaft rotation. Each time the piston changes direction, there is a knock from the metal hitting metal. This is often referred to as a "rod knock." It is usually very rhythmic—it increases with engine speed and intensifies with engine load.

    Other mechanical problems that lead to engine knocking are:
    Be sure to properly inspect and verify the root cause of the knocking sound, as it can be tricky to pinpoint. You don't want to replace the entire engine only to find out that the knocking was coming from a cracked hub on the transmission flywheel or flex-plate. Ouch!
    Just Another GSi Build Thread (Big BHP Build) - Feedback Thread (Comments appreciated )

  7. #7
    Status
    Offline
    trickyb's Avatar
    AOC Fanatic
    Join Date
    Aug 2005
    Posts
    954
    Mentioned in
    0 Post(s)
    Quoted
    0 Post(s)
    The knock sensor will only retard the ignition via the ecu as much as it can it wont always stop detonation as its been proved, it will come down to the map thats on the car, type of fuel, ammount of boost your running and sensors operating propperly. Running lean and running high power with the standard manifold will kill pistons without detonation (high exhaust temps).

Similar Threads

  1. Symptoms / Tell Tale Signs Of Buckled Wheels
    By MrStush in forum Astra Discussion & Chat
    Replies: 9
    Last Post: 07-04-2010, 08:50
  2. symptoms of bcs going?
    By sharmalini in forum Turbo Petrol Engines inc. Transmissions
    Replies: 8
    Last Post: 22-01-2010, 21:22

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •