How the Fuel and Ignition Systems Work

Here's how the fuel and ignition systems work to power the engine on your car!

There are three requirements for an internal combustion engine to work, fuel, air and spark.

The fuel system comprises of the fuel pump, fuel rail and fuel injectors that feed fuel into the intake plenum. The spark is governed by the ignition system, typically from a coil pack situated on top the spark plug. The air system is comprised of the air inlet, throttle body and intake plenum.

More information on the air intake system can be found in this video:

All of these components are controlled through the Engine Control Unit (ECU) that determines when and how combustion occurs in the 4 stroke cycle.

The ignition coil transfer the 12V signal from the ECU into thousands of volts needed to fire the spark plug. There are two windings of coil inside, that form a step-up transformer. The change in magnetic field when the coil is rapidly turned on and off causes the huge voltage spike needed to jump the spark plug gap. The timing of this is controlled by the ECU, which is typically just before the piston reaches top dead center.

The fuel injector has a small coil inside, when activated it forms an electromagnet. This sucks the pintle valve that was blocking gasoline flow up, allowing fuel to flow out the nozzle in a predetermined spray pattern, into the intake manifold on a port injected engine. The fuel mixes with the air stream and is then released into the combustion chamber on the piston's down-stroke when the intake valves open up.

Notable inputs to this closed-loop control system include driver input from the throttle, the throttle position sensor, oxygen (A/F) sensor, camshaft and crankshaft position sensor, knock sensor, mass airflow sensor and coolant temperature sensors.

OBDII readers can be found here:
Fuel injector cleaner can be purchased here:
Multimeter for diagnostics:
Replacement spark plugs (Iridium):
Replacement ignition coils can be found here:
Replacement oxygen sensor:

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[ajmeriaiyub]

No one can explain any car system like you thanks

[marcorizza]

Thank you ECU, thank you. And thank you brother's toothbrush too

[BlueMastic]

Just yesterday my car stopped working, turned out to be a faulty camshaft sensor which lead to misfiring in the engine. This video explains really well how it works and why this sensor is so important.
Your videos are great, thank you very much.

[dc]

Awesome explanation, thanks very much.

[DiegoMoonhaze]

I see Oral B finally made you an offer about product placement.

[xelaju]

I know you went to automotive school as soon as you mention the stoichiometric ratio. Great vid. Thanks. And for those who don't know, here it is. "The stoichiometric ratio is the exact ratio between air and flammable gas or vapor at which complete combustion takes place. The stoichiometric ratio of combustion varies for various fuels and oxidizers. If the engine has less air than the stoichiometric ratio, you have a rich mixture, because it is rich in gasoline." It is about complete or perfect combustion.

[johneric]

Terrific job, especially towards the end with the graphs showing how the air intake reading corresponds and affects other aspects. You really do a thorough job. I like how you cut open the parts and show them to your viewers. Your humor is just enough which shows a high degree of emotional intelligence. Because you combine high knowledge with everyday speech. I like when you say I'm going to use the specialty tool and then cut stuff open with your angle grinder; that's hilarious.

[johnfearn]

A brilliant explanation again! Thanks for taking the time to make these videos. I hope other people find them as interesting and informative as I do.

[ironmanbharath]

Thanks a lot and appreciate your hard work to explain us the things that even teachers forget to teach us. Lots of love from India 🇮🇳 keep growing.

[stefwdy]

I'm so amaze, how can you describe almost any car of a different make as you are involved with the design production and expert service technicians? You show us what's inside each component and how each one works. Bravo continues to work

[SECX]

Man, you are great. Are you willing to address fasteners in automotive applications someday? Especially about classes like for metric 8.8, 10.9, 12.9. I'd love it.

[alaautotonics]

awesome information thank your detailed explanation bro

[foxist]

Yes thanks you have opened my eyes to these types of systems.older fuel injection systems were way complicated.

Even though I'm sure you would be able to explain it in a simple term.lol .thanks again.

[roobear]

Very cool video... Amazing how all the parts and systems are orchestrated to work together

[Enigmaafk]

You’re a very good lecturer I would have had A+ if you were my teacher:) keep up the good work as always. I remember getting hit with some voltage with a defective spark plug leads.

[glasser]

pure Bliss !
I used to think comments from Mike Rowe were pretty amazing but here you cover everything perfectly well: theory & practice
🤗

[johnwallace]

Great. Knowledgeable and to the point. No theatrics and or trying to be movie director.

[arifbustani]

Your descriptions are short, sweet and pleasantly precise. Thanks.

[TheDrunkardHu]

... You lost me at "today"...






jk, this is a GREAT video! Very thorough, and concise with a dab of humor. Thank you for sharing!

[jcgeorge_]

I stumbled across this channel only just recently, but oh man, this is a goldmine of information. Thank you for the awesome, well-paced and well-explained video, very much appreciated!