![]() In most cases, it will be located on the left side of the engine block, immediately underneath the intake manifold.Ī vehicle specific service manual, such as one by Haynes or an OEM one, can be used to confirm its location. Your vehicle’s knock sensor will most likely be found on the engine block, either on the intake manifold or cylinder head. Automatic transmissions will likely handle this for you. If you drive a manual transmission vehicle that is both direct injected and turbocharged, consider downshifting before you floor it. Supposedly there are engine oils that can mitigate this phenomenon, but nothing can prevent it entirely. ![]() On newer vehicles that have both direct injection and a turbocharger, there is an increased probability to experience pre-ignition when the driver requests a lot of torque at a low low engine speed.Īutomotive engineers aren’t quite sure why this phenomenon occurs, but it is thought to be caused by the higher cylinder pressures typically seen on direct injected turbocharged motors with a relatively high compression ratio. If your knock sensor were to malfunction or go bad in your vehicle, there would be some noticeable symptoms that would present themselves. This will help prevent damage to the engine as it goes through the pre-ignition process. The main downside is that your car will be slower until the ignition timing returns to normal. Lowering the power output by retarding the ignition timing will decrease cylinder pressures, making the combustion event safer for the engine. The piston will be a little higher in the cylinder and the combustion event will not make as much power on the combustion stroke. Retarding (delaying) the ignition timing means the spark plugs fire a bit later than they used to. From there, the module will delay the ignition’s timing and prevent engine detonation. Cruising knock is very common and much less concerning.Īn engine knock sensor is designed to detect these unplanned explosions and send a voltage signal to the ECU or powertrain control module. Cruising knock happens while driving at a constant speed. There are countless variables in the environment that can’t always be controlled for, such as carbon buildup, fuel quality, and quick changes in the position of the throttle plate such as stabbing the gas.Įngine knock is usually only harmful when it happens at high loads, such as when you’re at full throttle. Virtually every engine knocks to some extent. That moment is usually just before the cylinder reaches top dead center (TDC) on the compression stroke. This air fuel mixture must be ignited at precisely the right moment. I'll bet the fellows who run professional shops here don't have them pop out either.Engine knock, pre-ignition, and pre-detonation are all names for explosions in the combustion chamber that happen when they’re not supposed to.Ī combustion engine requires a carefully balanced mix of air and fuel. And many, many of those were aluminum heads, including MINIs. Personally I've never had a plug come loose on any head, aluminum or otherwise in the 50+ years I've been putting them in internal combustion engines. It's pretty simple, tighten them down till they crush the washer, then torque to spec. I've never heard of a plug installed by the mfr that came out. Then their misunderstanding gets reposted all over the net as fact.Įvery one of these I've ever heard of that popped out were shortly after the plugs had been changed - improper installation. ![]() ![]() There is nothing wrong with the heads, nothing different about them that requires any sort of different procedure than any other aluminum head.īut there seem to be a few people who don't understand the right way to install the plugs and that's what causes the problem. You do not have to re-torque them - ever - if you install them correctly. Click to expand.Well, as I said before if the plugs are installed properly they don't come out.
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