Advertisement On four-cylinder engines, the 2 and 3 injectors are in the hottest location and tend to clog up faster than the end injectors on cylinders 1 and 4. The same applies to the injectors in the middle cylinders in six- and eight-cylinder engines. The hotter the location, the more vulnerable the injector is to clogging from heat soak. The cure for dirty injectors is to clean them on-car or off-car with special injector cleaning machine , or to replace them if cleaning fails to restore a normal flow rate and nozzle pattern.
The magnetic field must be strong enough to overcome the spring pressure and fuel pressure above the pintle, otherwise the injector may not open all the way or not open at all. Shorts, opens or excessive resistance in the injector solenoid can also cause problems. Advertisement Typically, when injectors fail, the solenoids often short internally causing a drop in resistance. If the specification calls for 3 ohms, for example, and an injector measures only 1 ohm, it will pull more current than the other injectors.
Too much current flow to an injector may cause the PCM injector driver circuit to shut down, killing any other injectors that also share that same driver circuit. One way to check the injectors is with an ohmmeter key off. Look up the specifications, rather than guess. The specs are fairly narrow, and with good reason.
Advertisement So if the factory specifications call for 12 to 16 ohms of resistance, and you find several injectors that are only a few ohms higher or lower, the injectors should probably be replaced. If you find one or two that are noticeably lower or different than the others, they probably need to be replaced.
Just clamp the amp probe around one of the injector connector wires. When the PCM energizes the injector, current starts to flow through the circuit. This causes the waveform on the scope to ramp up. When the PCM opens the ground circuit to turn off the injector, the pattern drops back to zero.
Advertisement On engines that have low-resistance peak-and-hold style injectors, the scope will typically show a pattern with a sharp peak that drops to a plateau until the injector turns off, then it spikes again two peaks total in the pattern. The peak is typically at 4 amps and the hold plateau portion of the pattern is at 1 amp. And if you see a sharp vertical rise in the current pattern, it means the injector is bad.
A shorted injector can sometimes pull down the PCM driver circuit, preventing other injectors from firing depending on how the PCM driver circuits are configured. Advertisement On most vehicles, the injectors receive battery voltage when the ignition is on, and the PCM driver circuit provides the ground connection to turn the injectors on and off.
Therefore, if you have a dead injector, one of the first things to check would be voltage at the injector terminal. If more than one injector is getting low voltage, the fault may be a bad injector power supply relay. When the PCM energizes grounds the injector circuit, the voltage reading on the supply side should drop to zero as long as the injector is energized.
This verifies the PCM ground drive circuit is working and that current is flowing through the injector. Advertisement When the PCM opens the injector circuit, it creates a momentary voltage spike, which can be seen on an oscilloscope if you hook up the scope to the injector circuit.
When the injector pintle closes, it creates a little bump in the scope pattern, which should be consistent from one pulse to the next. If the scope shows multiple bumps or the pattern is changing, it means the injector pintle is sticking or the injector is dirty. If injectors need to be replaced, you can install new or remanufactured injectors. Reman injectors are used injectors that have been cleaned and tested to make sure they meet OEM specifications.
Post by Big Pete » Thu Mar 13, am. Post by Knowmarine » Fri Mar 14, am. Privacy Terms. Skip to content. Quick links. Typically, "rough idling" is characterized by varying revolutions per minute RPMs , even when you have your foot off the pedal. Often, rough idling is accompanied by engine stalling — a sudden decrease in RPMs and engine noise that feels like running out of gas on a hill. Dirty fuel injectors are only one of several engine problems that can result in rough idling and engine stalling.
If you notice these issues in your car, come in for a Complete Vehicle Inspection. Our expert technicians will get to the bottom of the problem and recommend a fuel system cleaning if needed. Well-performing fuel injectors help your vehicle get the kind of gas mileage that manufacturers promote. While a variety of engine issues can cause you to stop by your local gas station more often, lousy gas mileage could be a signal that something is wrong with your fuel injectors.
Typically, you control what your car's dash gauges do. When you drive a lot, the gas needle moves from "F" to "E. What do dirty fuel injectors do? They can cause the needle on the tachometer — the gauge that displays the vehicle's RPM — to move unpredictably.
You may notice the needle moves unprompted, indicating changes in RPM when your car isn't switching gears. Fuel injectors deliver gas to the appropriate cylinders.
That's Job 1. And when Job 1 isn't getting done, your engine won't receive its crucial combination of air and fuel. Fact is, you can use too much Techron and cause damage to your fuel tank lining. You mention the vehicle runs better after you use it. After you have it down that low, you should probably take around 15 gallons of fresh fuel.
Check on the back of the bottle for the proper amount of Techron for that much fuel. Sadou Josebe Beginner. What causes injectors to fail? Fuel injectors will fail when debris water, dirt particles, etc. To prevent debris from getting into the system, we recommend doing everything you can to help keep your fuel system clean. Dolores Temel Beginner. Is carb better than fuel injection? Carburetors are also much simpler to install than fuel injection systems, because there are no electrical components or return lines to the fuel tank.
The carburetor is currently much less expensive than the electronic fuel injection systems. Crisanta Abadiano Beginner. Where is the fuel injector located? Fuel Injector Location. Lukene Dahov Beginner. Which gives more mileage carburetor or fuel injection? For a layman, as the name suggest, Fuel Injection system injects fuel into the engine optimally such that only required fuel is used by the engine and thus gives out better fuel economy.
Whereas, in a Carburetor the air intake is via the air filter and the fuel intake comes in from the fuel tank. Audrea Raton Beginner. What is the difference between fuel injection and direct injection? Direct Injection and Port Injection use computer-controlled electric injectors to spray fuel into the engine.
The difference is where they spray the fuel. Direct injection has the injectors mounted in the cylinder head and the injectors spray fuel directly into the engine cylinder. It then mixes with the air. Ask A Question. Co-authors: Updated On: 9th July,
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