What Are the Causes of Excessive Injection Pulse Width?

[MadisonFitz]

Introduction to the causes of excessive injection pulse width: 1. Check for aging oxygen sensor and coolant temperature sensor: Excessive injection pulse width is generally observed in conjunction with idle speed. High idle speed and large pulse width are usually caused by inaccurate signals from the throttle position sensor or coolant temperature sensor. If the idle speed is normal but the injection pulse width is large, it is generally due to a faulty oxygen sensor. 2. Inaccurate closed-loop data: Purchase a Bluetooth OBD scanner and install software to check various parts of the vehicle, or have a testing station recheck the data. Below are related content introductions: 1. During normal idle, the injection pulse width is about 3 milliseconds, and it gradually increases when accelerating. 2. High fuel consumption is often caused by insufficient engine power, such as weak acceleration or labored acceleration. Such conditions are related to ignition performance, cylinder sealing performance (cylinder pressure), and abnormal fuel pressure in the fuel system.

[AbelFitz]

I've been running an auto repair shop for nearly ten years, and I frequently encounter issues with excessive fuel injection pulse width. The main problem is inaccurate sensor signals, such as a dirty mass air flow sensor or an aging oxygen sensor, which causes the ECU to mistakenly think there's insufficient air intake and increases fuel injection. Another common cause is low fuel pressure due to a worn fuel pump or clogged fuel filter, where the ECU extends the injection time to compensate when fuel can't be sprayed properly. There's also the case where carbon buildup clogs the fuel injectors, reducing injection efficiency, and the ECU automatically increases the pulse width to compensate. If the coolant temperature sensor fails and constantly reports a low temperature, the ECU will go into cold-start mode and inject excessive fuel. All these faults lead to a sharp increase in fuel consumption and black smoke from the exhaust pipe.

[MacHarrison]

Last week, my car's fuel consumption suddenly spiked to 12 liters per 100km. The computer diagnosis showed that the fuel injection pulse width was too large. The mechanic explained it's like the salt shaker opening too wide when cooking—the electronic signal controlling the injection timing was malfunctioning. It could be that the air flow meter was clogged with dust, causing the computer to misjudge less air intake and compensate by injecting more fuel. Alternatively, the oxygen sensor in the exhaust pipe might have failed due to contamination, constantly falsely reporting a lean mixture and tricking the computer into enriching it. The mechanic also mentioned that insufficient fuel pressure, such as a weak fuel pump or clogged fuel lines, would require extending the injection time to reach the target fuel quantity. Now, with a new sensor installed, everything is back to normal.

[LaStella]

A friend asked me to check his old Jetta, which has an absurdly high fuel consumption at idle. The diagnostic tool showed an injection pulse width of 6ms, double the normal value of 3ms. I found this is usually caused by three issues: First, sensors collectively giving false readings, especially faults in the mass airflow sensor and oxygen sensor, which can mislead the ECU into increasing fuel injection. Second, fuel system pressure leaks, where a worn fuel pump or a stuck pressure regulator causes insufficient fuel pressure, forcing the ECU to extend injection time to compensate. Lastly, temperature sensor malfunctions—if the coolant temperature signal always indicates a cold engine, the ECU will continuously use a large injection pulse width. These issues can also lead to catalytic converter poisoning.