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I saw similar topics but that did not explain my things... As we can see 4 stroke engine with 4 pistons

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Is there any chance (only for test) to 'switch-off' two pistons? For this example I'm talking about spark plug/EFI disconnect of two pistons. Is there any chance so car with 4 pistons will works fine with only 2 pistons (as I say 2 pistons without EFI/Spark plug connect). I test it on my second car but disconnecting two pistons gives a result that car vibrated and wasnt 'stable' as normal (perhaps maybe there was knock detonation).

Can someone explain this in simple words and 'science' words?

Thank You.

Zaid
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dexzuo
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2 Answers2

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As you saw with your test, it is possible to disconnect the ignition on two pistons and still have the engine run.

The vibrations have nothing to do with engine knock or detonation though. The reason it stumbles is because those disabled pistons were expected to sustain the crank's rotation. In the absence of those pistons firing, the crank will experience rotational acceleration/deceleration.

It is a good idea to disconnect the fuel injectors to those cylinders during the test to prevent unburnt hydrocarbons from reaching the catalytic converter.

Zaid
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Don't know why would you need to do that, but yes, you only need to remove spark plugs to decompress unused cylinders. You can disconnect injectors, but the fuel will run out through spark plug holes anyway..

Arturs Bolsunovskis
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