What causes fuel injectors to spray?
03-22-2016, 06:52 PM
#1
Thread Starter
What causes fuel injectors to spray?
Here's my dumb question of the week:
What conditions causes the fuel injectors to spray during the turning-your-car-ON process?
(I'm asking because I've read other people flooding their engine/oil with gas -- either from leaking injectors, pumping the accelerator pedal, etc. When I turn my car off, I have it in gear, I turn the keys off, let out the clutch [to park in gear], then turn the keys back to ON so I can have power to put my convertible top up. Wondering if that cycle is unnecessarily spraying extra fuel into my cylinders each time??
Thanks!
What conditions causes the fuel injectors to spray during the turning-your-car-ON process?
- Specifically, key turned all the way, all the dash lights are on (but engine is off), did the injectors spray?
- Or will they only spray when key turned all the way + press the red START button?
- Also will they spray if the keys are on, engine off, but I pump the accelerator pedal?
(I'm asking because I've read other people flooding their engine/oil with gas -- either from leaking injectors, pumping the accelerator pedal, etc. When I turn my car off, I have it in gear, I turn the keys off, let out the clutch [to park in gear], then turn the keys back to ON so I can have power to put my convertible top up. Wondering if that cycle is unnecessarily spraying extra fuel into my cylinders each time??
Thanks!
03-22-2016, 07:23 PM
#2
There are some fundamentals that you must be aware of. Your engine, actually each cylinder, individually go through 4 cycles. Induction, compression, combustion, exhaust. These are timed and happening at very precise moments by your ECU. It knows that, let's say, cylinder 1 is in the induction phase. It needs to supply fuel (and air) so at this point in time it knows to fire the injector at cylinder 1. It can see this because you have your Camshaft Position Sensor because your camshaft is what dictates what phase you are in the cycle. Every cylinder is in a different phase.
To answer your question about people flooding their motor, when you pull the spark plug or coil or if you have a bad plug or coil, your cylinder is not combusting. Meaning the fuel being supplied by the injector is not being used, it's just bein built up.
What your are asking in bold is what we call a "leaking injector" in other words it is firing at times the ecu is not asking it to. And no, you are not spraying fuel into the cylinders. The only time it will spray is when your camshaft moves into place so that your Camshaft Position Sensor sees that it's in that phase and it tells your ecu to fire the injector in which the ecu tells it to go.
Longest explanation ever but basically, with the key on (accessories on) and engine (not running) off you are not flooding your engine.
To answer your question about people flooding their motor, when you pull the spark plug or coil or if you have a bad plug or coil, your cylinder is not combusting. Meaning the fuel being supplied by the injector is not being used, it's just bein built up.
What your are asking in bold is what we call a "leaking injector" in other words it is firing at times the ecu is not asking it to. And no, you are not spraying fuel into the cylinders. The only time it will spray is when your camshaft moves into place so that your Camshaft Position Sensor sees that it's in that phase and it tells your ecu to fire the injector in which the ecu tells it to go.
Longest explanation ever but basically, with the key on (accessories on) and engine (not running) off you are not flooding your engine.
03-22-2016, 09:44 PM
#3
Thread Starter
There are some fundamentals that you must be aware of. Your engine, actually each cylinder, individually go through 4 cycles. Induction, compression, combustion, exhaust. These are timed and happening at very precise moments by your ECU. It knows that, let's say, cylinder 1 is in the induction phase. It needs to supply fuel (and air) so at this point in time it knows to fire the injector at cylinder 1. It can see this because you have your Camshaft Position Sensor because your camshaft is what dictates what phase you are in the cycle. Every cylinder is in a different phase.
To answer your question about people flooding their motor, when you pull the spark plug or coil or if you have a bad plug or coil, your cylinder is not combusting. Meaning the fuel being supplied by the injector is not being used, it's just bein built up.
What your are asking in bold is what we call a "leaking injector" in other words it is firing at times the ecu is not asking it to. And no, you are not spraying fuel into the cylinders. The only time it will spray is when your camshaft moves into place so that your Camshaft Position Sensor sees that it's in that phase and it tells your ecu to fire the injector in which the ecu tells it to go.
Longest explanation ever but basically, with the key on (accessories on) and engine (not running) off you are not flooding your engine.
To answer your question about people flooding their motor, when you pull the spark plug or coil or if you have a bad plug or coil, your cylinder is not combusting. Meaning the fuel being supplied by the injector is not being used, it's just bein built up.
What your are asking in bold is what we call a "leaking injector" in other words it is firing at times the ecu is not asking it to. And no, you are not spraying fuel into the cylinders. The only time it will spray is when your camshaft moves into place so that your Camshaft Position Sensor sees that it's in that phase and it tells your ecu to fire the injector in which the ecu tells it to go.
Longest explanation ever but basically, with the key on (accessories on) and engine (not running) off you are not flooding your engine.
03-23-2016, 01:27 AM
#4
When you first turn the key to the ENGINE ON position, the fuel pump in the tank pressurizes the fuel system by running a few seconds. It brings the fuel system up to a set level through a regulator at the engine fuel rail. Any excess gas that causes the pressure to exceed that specified level gets sent back to the fuel tank.
The fuel injector is simply an on-off sprayer that operates for a duration of time when the ECU tells it to, expecting a constant fuel pressure.
If you don't pause and allow the fuel pressure to build up to that expected level, you might get less than expected metered amount of fuel for combustion.
The throttle plate is not attached to the fuel line. It is therefore incorrect to call it a gas pedal on fuel injected cars. Instead, the accelerator pedal is connected to the butterfly valve on the intake air. Sensor(s) detect how much opening you are calling for on the throttle plate and send that information to the ECU for determining the length of time to spray the injector.
However, the ECU will not activate the injectors when the engine crankshaft is not physically rotating. The ECU turns on the fuel injector only when a sensor knows each cylinder is reaching the proper alignment for fuel to be delivered.
Therefore, the "gas" pedal does nothing when the car is not running, and pressing on the accelerator pedal does nothing if it is not.
The right thing to do when starting the car is wait two seconds after turning the engine on before pressing the red button. The ECU does all the thinking about how much fuel is needed, you just need to make sure the pressurized fuel is in the rail. Any attempt to provide extra fuel by using the gas pedal accomplishes nothing beneficial, but "giving it gas" could result in confusion at the ECU because you are making it's job more complicated.
The fuel injector is simply an on-off sprayer that operates for a duration of time when the ECU tells it to, expecting a constant fuel pressure.
If you don't pause and allow the fuel pressure to build up to that expected level, you might get less than expected metered amount of fuel for combustion.
The throttle plate is not attached to the fuel line. It is therefore incorrect to call it a gas pedal on fuel injected cars. Instead, the accelerator pedal is connected to the butterfly valve on the intake air. Sensor(s) detect how much opening you are calling for on the throttle plate and send that information to the ECU for determining the length of time to spray the injector.
However, the ECU will not activate the injectors when the engine crankshaft is not physically rotating. The ECU turns on the fuel injector only when a sensor knows each cylinder is reaching the proper alignment for fuel to be delivered.
Therefore, the "gas" pedal does nothing when the car is not running, and pressing on the accelerator pedal does nothing if it is not.
The right thing to do when starting the car is wait two seconds after turning the engine on before pressing the red button. The ECU does all the thinking about how much fuel is needed, you just need to make sure the pressurized fuel is in the rail. Any attempt to provide extra fuel by using the gas pedal accomplishes nothing beneficial, but "giving it gas" could result in confusion at the ECU because you are making it's job more complicated.
03-23-2016, 05:08 PM
#5
turning the key to the on position on does not cause the injectors to "spray", it only pressurizes the fuel line as the fuel pump activates for a few seconds. If you have leaky injectors that could cause fuel to leak into the cylinder, but that is not normal for them to leak unless they are faulty.
There is a condition that can kill a motor, I think it is when you get a faulty 02 sensor code and you continue to try and run the motor and things go full rich and fuel will wash down the cylinder walls and kill the motor and bearings due to fuel dilution.
There is a condition that can kill a motor, I think it is when you get a faulty 02 sensor code and you continue to try and run the motor and things go full rich and fuel will wash down the cylinder walls and kill the motor and bearings due to fuel dilution.
Thread
Thread Starter
Forum
Replies
Last Post