What Causes Excessive Cold Start Injection Pulse Width in BMW N20 Engine?
4 Answers
Excessive cold start injection pulse width in BMW N20 engine is caused by abnormal sensor signals of the injection pulse width. Concept of Injection Pulse Width: The unit of injection pulse width is milliseconds (ms). A larger displayed parameter value indicates longer opening time of the injector each time, resulting in richer air-fuel mixture for the engine; while a smaller value indicates shorter opening time, leading to leaner air-fuel mixture. Range of Injection Pulse Width: There is no fixed standard for injection pulse width as it varies with engine speed, load, and intake air volume. The ECU calculates or queries the database based on these parameters to determine the specific injection pulse width value, typically ranging between 1.5ms to 2.9ms.
I've been driving a BMW for several years and encountered the issue of the N20 engine's prolonged fuel injection time during cold starts. The main cause is often a malfunctioning coolant temperature sensor, which mistakenly thinks the engine is still cold and commands extra fuel injection to warm it up quickly. I've had this fault on my car, and it returned to normal after replacing the sensor. Other causes include carbon buildup in the fuel injectors causing unstable fuel supply, or a software bug in the engine control unit failing to adjust parameters in time. It's not hard to diagnose—first, scan for trouble codes with a diagnostic tool to confirm the source of the issue, instead of disassembling parts randomly for repairs. Ignoring it long-term will waste fuel, increase carbon deposits, and even affect exhaust quality. It's recommended to pay extra attention to cold-start performance in winter and address any issues promptly to save a lot on fuel costs.
As a car owner, I find the excessive fuel injection during N20 cold starts quite annoying. It might be related to the aging of the intake air temperature sensor, which inaccurately signals the ECU to inject more fuel. Dirty fuel injectors can also cause this issue, requiring longer opening times to compensate for fuel supply. You might notice white smoke from the exhaust pipe or a significant spike in fuel consumption. I tried cleaning the air filter and fuel injectors myself, but when that didn’t help, I sought professional help to check the circuitry. Remember, regular maintenance can prevent many such issues—don’t wait for minor problems to turn into major repairs.
My N20 engine exhibits excessive fuel injection pulse width during cold starts, typically due to sensor malfunctions or system misjudgment. Priority checks should focus on the coolant temperature sensor and fuel injectors, replacing or cleaning them if necessary. Control module signal deviations or fuel pressure issues can also trigger this problem. Early repairs can prevent additional fuel consumption and excessive emissions.
