You may need to clean fuel injectors if your engine is experiencing hard-stars, hesitation, rough idle, power lose, or misfires. Some impurities and chemical compounds in the fuel get stuck in fuel injectors’ passages (turn into varnish), restricting or blocking fuel flow over time.
These partially blocked or clogged injectors will cause the engine to idle erratically, make it hard to start and misfire. When the problem has just started and the contaminants have not had a chance to bake themselves around the injectors passages yet, you can remove these deposits using special fuel additives designed to clean and clear fuel injectors. But badly clogged injectors will require a most drastic solution.
Either way, read on and clean those dirty injectors using this guide. You’ll also find recommendations about other sensors in the engine systems you can check if cleaning the injectors don’t solve your problem completely.
Servicing Fuel Injectors
1. Add a quality additive fuel injector cleaner to the fuel tank. Seafoam motor treatment is a popular and quality product for this purpose. I’ve used it myself with good results. Other products you might want to try as well are Techron injector cleaner and Marvel Mystery Oil.
Besides helping clear fuel injectors, some of these products have other benefits like help control moisture in the fuel tank, and removing carbon deposits from valves and cylinders.
Carefully read the manufacturer instructions of the product you decide to use.
This method seems to work pretty well now that varnish is less of a problem with today’s fuel quality. Problems usually arise on high mileage vehicles—with 100,000 miles or more—when fuel system maintenance have been neglected, like regular fuel filter changes and forgetting to add a cleaning additive from time to time.
However, fuel injector cleaning may not work on a severely clogged injector. To clear the valve and nozzle, you’ll probably have to take your car to the shop.
2. You still have another option, though: A fuel injector cleaning kit that will help you unclog badly blocked fuel injectors.
But the price you pay for a decent kit (above $200.00 dollars), the number of times you’ll actually use it, and the risk of damaging one or more injectors (plus the fuel regulator, or some other system component), it may turn out too expensive compared to the cost of having a professional shop do it instead.
Taking Your Car to the Shop
Do some research before going to the first repair shop offering a great deal on fuel injectors service. You may see shops advertising a cheap fuel injection cleaning job that consists of a solution added to the fuel tank.
Make sure that the shop will actually run a cleaning solution directly to the fuel injectors. With an in-place cleaning operation, the solution is run through the fuel rail with air pressure to help remove carbon buildup and hard to remove varnish inside the injectors.
On tough jobs, a shop will recommend removing the injectors from the fuel rail and cleaning them separately. You pay more for this type of service (about $20 to $30 dllrs. per injector) but not as much as you would if you had to replace the injectors.
Either of these methods is a good option when working with hard to clear injectors.
What if My Fuel Injectors Are Not the Problem?
Unfortunately, partially or completely clogged fuel injectors are not the only reason for bad engine performance. Other problems, like a malfunctioning injector, failing to replace a filter, a component that needs some cleaning, lack of maintenance or even a failing sensor, may produce symptoms similar to those of a restricted fuel injector.
After cleaning the fuel injectors, if engine performance problems persist, here is a list of maintenance items—including sensors—that you might want to check to help you restore fuel economy and proper engine performance.
The vehicle service manual for your particular model comes in handy when checking, troubleshooting, replacing components, or maintaining the different systems in your car. You can but an inexpensive aftermarket repair manual online or at some local auto parts store.
1. Checking fuel injectors’ operation
Fuel injectors not only clog after miles of operation; They’re also bound to fail, showing similar symptoms of a blocked injector. You can use a simple test to check that each injector is running.
* Use a mechanic’s stethoscope or large screwdriver to listen to each injector opening and closing as the engine idles.
* If you want to use a screwdriver, place the driver’s tip against the injector’s body and the end of the driver’s handle against you ear.
* If you don’t hear the injector’s clicking sound during operation, you might’ve found a dead fuel injector.
* Also, your vehicle service manual might have the instructions to check the injectors’ resistance using a digital multimeter. You can do this test at home yourself and confirm right away if an injector has electrically failed.
Watch the next video so that you have an idea how you can do it yourself.
* Follow the instructions listed in your service manual for further tests, if necessary.
2. Servicing fuel and air filters
These filters represent common, but often overlooked, maintenance items. Consult your car owner’s or vehicle service manual for the filters’ replacement interval. Replace them if necessary. Over time, dust and foreign particles clog the filter element, restricting fuel or air flow.
If you haven’t followed the recommended service intervals, the fuel filter may have started to interfere with fuel flow (just like a dirty fuel injector) and fuel pump operation. Failing to replace a restricted or clogged fuel filter will cut short the fuel pump’s service life as well. If your manufacturer didn’t schedule a service interval for your fuel filter, replace it at least every 12 months to guarantee proper fuel flow.
3. Checking ignition system components
Your vehicle service manual will give you the service interval for the different components in the ignition system, which may also produce symptoms similar to those of bad fuel injectors. Check or replace spark plugs, spark plug wires, distributor and ignition coil. Your manual describes the right procedure to check or replace these components.
4. Cleaning the throttle body
Check and clean, if necessary, the throttle body as well. Removing the layer of carbon buildup around the air horn and the throttle plate will clear the passage and make sure the throttle plate closes as it should, preventing rough idle. Spray some carburetor cleaner on a clean rag and use the rag to clean the throttle body.
5. Checking the fuel pressure regulator
This is another important component to check. Although you may not want to run tests on the regulator during a routine check (unless you suspect a failure) you may want to inspect the vacuum hose connected to it (on vacuum operated regulators), the condition of the electrical connector and wires. Consult the service manual for your particular model for the correct way to check the fuel pressure regulator on your vehicle.
6. Manifold absolute pressure
The Manifold Absolute Pressure (MAP) sensor reads engine vacuum and sends the appropriate signal to the vehicle’s computer. The computer uses this signal to regulate fuel, ignition timing, and other engine performance events. Inspect the electrical connector and vacuum line, if used.\
7. Inspecting the oxygen sensor
Inspect the oxygen sensor’s electrical connector as well. A malfunctioning oxygen sensor will upset the fuel injection and emissions system. A bad oxygen sensor may cause the car’s computer to feed too much or too little fuel to the engine, affecting engine performance. Your vehicle service manual may give you the procedure to check the sensor operation using a digital multimeter and its service interval.
8. Checking the Throttle Position Sensor – TPS
A malfunctioning TPS will prevent the computer from metering correctly fuel delivery as well, sometimes preventing the engine from starting. Inspect the TPS electrical connector and wires condition. Your service manual may tell you how to check the TPS using a digital multimeter as well.
9. Other sensor to keep in mind
Other sensors to check when servicing your fuel injection system include the Engine Coolant Temperature (ECT) sensor, Intake Air Temperature (IAT) sensor, and mass air flow (MAF) sensor.
10. Using a scan tool
Simple visual inspections can’t reveal the actual condition of the many sensors found around your engine. But you can use a scan tool or code reader to make it easier to inspect.
You can find relatively inexpensive scan tools on most auto parts stores and online. Using the scan tool, you may find diagnostic trouble codes (DTC) stored in the computer’s memory for any of those fuel system related sensors.
Still, if you don’t want to buy a scan tool or code reader now, check with your local auto parts store. They may pull any trouble codes from your car’s computer for free. A stored code may tell you if a suspected sensor or component has something to do with an engine malfunction. The next video gives you an idea how you can use a scan tool to check malfunctioning sensor that might be affecting engine performance.
Depending on the type of fuel delivery system on your car—conventional, pulse-modulated or direct injection—you may find fewer or more components and sensors affecting the fuel system on your vehicle than those listed here. Consult your vehicle service manual for this information and follow the manual’s guidance to inspect for loose wires and vacuum hoses condition that can affect proper fuel delivery.
The best way to clean fuel injectors is to prevent dirt, contaminants and buildup from clogging passages in the first place. Add a quality additive to the fuel tank from time to time as a preventive measure, and change the fuel filter every year. You’ll reduce the possibility of breakdowns, save on fuel and costly repairs.