Do You Have Bad Fuel Injectors?

The standard combustion automobile has followed the same basic combustion cycle and similar engine architecture for almost 100 years now, stemming from the original Ford Model A. The original systems used what’s called a carburetor to mix the air and fuel entering the motor in an approximate ratio of 14.7 parts oxygen to 1 part gasoline (commonly shown as 14.7:1) but due to the lower levels of control of distribution and atomization that were intrinsic to the design of the system, that ratio could fluctuate greatly from cylinder to cylinder, and even from one wide open throttle test to another. One of the first steps to rectifying this (and arguably one of the most vital) was the introduction of fuel injection in the mid-1950s, starting with the Mercedes Benz 300SL Gullwing in 1955. This technology helped propel that car to becoming the fastest car ever produced at the time! This took a while to work out the kinks and become standard practice, but by the ’80s, almost all manufacturers had fully dropped the carburetor from their production cars. 

What is fuel injection? Where the carburetor worked by a controlled leak of fuel above the intake manifold that then got sucked into the motor from the intake vacuum pressure, electronic fuel injection uses pressurized fuel lines leading to a valve either directly above each cylinder in the intake manifold or directly bolting into the cylinder. This allows a computer to accurately control how much fuel is injected into each cylinder independently for any rpm or throttle position, and completely eliminates all of the hotspot issues, cylinder starvation, and over-fueling problems! As long as they’re working, that is. Which begs the question… 

Do You Have Bad Fuel Injectors?

With that brief history and function lesson out of the way, now we need to make sure ours are functioning properly. Thankfully virtually all fuel injectors work the exact same way, so checking on them will be the same regardless of what car you drive. These are a very simple (but precise) mechanism, where electric current supplied by the engine’s computer will open and close a small valve for a specific amount of time once per combustion cycle (during the intake stroke). Since they are so simple, they usually are one of the longer-lasting components on the engine unless the motor is tuned for greater output, so most likely they will need to be cleaned rather than replaced. It’s common for older or higher mileage engines to get dirty, or sometimes either the wire leading to it, or the electrical connection itself can get corroded or short leading to improper function of that injector. 

Most commonly an injector won’t actually be bad, but instead stuck from a buildup of contaminants from the fuel (usually caused by either cheap fuel or bad additives), and fixing a stuck injector can be as simple as just using a fuel injector cleaner mixed into the gas tank next tiny you fill-up. These contain engine-safe solvents that work to dissolve/break down any of the buildups that may be affecting the injector as it passes through.

Do All Fuel Injectors Go Bad?

Yes. These are a standard consumable part for your automobile, though usually very long-lasting. Since they operate independently of one another, and there are just as many of them as there are cylinders in your motor (a V8 will have 8, and inline 4 will have 4, etc) they will only affect one cylinder when one goes bad, so they can also be replaced one at a time which can mitigate parts cost. Though depending on your vehicle and if you’re doing it yourself, the labor cost or personal time necessary to get each one out can make it more cost-efficient to replace them all at once. 

What Causes Fuel Injectors to Go Bad?

Even though they’re very simple and have only one purpose, there are still a few different things that can lead to a failure or malfunction:

  • Wear / Age – Things get old, and each of these is firing once per rpm of the motor, so with a standard drive around 1,800 rpm for 20 minutes, each injector has worked 36,000 times! It’s a wonder that they last at all, but they commonly will last upwards of 15 to 20 years on a well-maintained car!
  • Bad Gas – The main part to fail here is the opening valve on the injector, and only two things touch this: air and fuel. Some cheap fuel (or low-quality additives) can lead to a gummy buildup on the valve, causing it to stick at virtually any point in operation (though most commonly closed position). A good injector cleaner will usually take care of this if the injector isn’t too far gone. 
  • Corroded Connectors – Since these operate based on electrical impulse from the ECU (engine control unit), if the connector is worn or corroded from age, water intrusion, or manufacturer defect it can’t get the proper signal to open or close.

Can You Drive With Bad Fuel Injectors?

Can you? Yes. Should you? No. 

If you have one or more cylinders operating poorly, not only will this usually throw a check engine light letting you know to fix it, but it will also affect engine performance and can cause damage to the affected (and surrounding) cylinder since the engine partially uses the fuel to cool the cylinder. This can also wreak havoc on turbo efficiency, since there will be uneven exhaust pulses from the bad cylinder, possibly causing extra wear here also. 

What Do You Do If You Have Bad Fuel Injectors?

Replacing a failing injector, or cleaning a stuck one is paramount to proper engine operation and a long life for your motor. Checking if you have a bad or clogged / dirty injector is usually a quick process for any shop to do during a fuel injection system service, and the replacements shouldn’t take more than a day for most models of vehicles. Though the process can be expensive for labor for some cars, this is a very important part to have replaced as early as a problem is discovered. 

If you’re in Portland, Oregon and looking for a reliable mechanic, schedule a service with our team and we’ll get your car in top shape!

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Many auto owners struggle to know if the right work was done the right way on their car. As a courtesy, we provide digital vehicle inspections and photos so you can quickly and easily see what our experienced, professional technicians are seeing. Overall, we go the extra mile to help you make informed decisions on the repair and maintenance plan of your vehicle, so you can drive with confidence every time you get behind the wheel.