Harley MAP Sensor Failure Symptoms (8 Failure Symptoms)

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If your Harley-Davidson motorcycle is experiencing performance issues, one possible cause could be a malfunctioning MAP sensor.

It is an important component of the exhaust system that regulates air-fuel ratios and provides data to the engine control unit.

When it fails, you may experience a range of symptoms that can have an adverse effect on power output and efficiency.

 Knowing how to recognize the symptoms can help you quickly diagnose MAP sensor failure in your Harley-Davidson motorcycle.

Harley MAP sensor failure symptoms

These are the most common symptoms of the Harley MAP sensor failure.

1. Misfires 

Misfires are one of the most common and noticeable symptoms of a faulty Harley MAP sensor.

It occurs when the engine fails to ignite the fuel mixture injected into its cylinders, resulting in inadequate combustion that reduces power and can cause other issues. 

When a MAP sensor fails, it can cause incorrect readings, resulting in irregular fuel trimming or incorrect air/fuel ratio calculations.

This will affect the amount of fuel entering each cylinder, often resulting in a misfire.

The misfire may be intermittent or continuous, depending on how severe the issue is.

If the MAP sensor is not sending accurate readings, it can lead to decreased performance and poor emissions due to incomplete combustion.

2. Poor fuel economy

Excessive fuel consumption can occur due to an inappropriately low or high pressure reading from the MAP sensor.

Poor fuel economy can be caused by numerous issues; however, if all other components are functioning normally, it may be worthwhile to investigate the condition of the MAP sensor.

In order to assess the condition of the MAP sensor, you should first use a digital multimeter to test for voltage at specific points on the sensor.

If there are no readings or any inconsistencies present, then it is likely that the component needs to be replaced as soon as possible.

3. Slow acceleration 

The MAP sensor monitors the air pressure in the intake manifold and sends signals to the engine unit, which adjusts the fuel/air mixture for optimal combustion.

When this sensor malfunctions, it can result in an incorrect fuel/air ratio that can cause the motorcycle to experience sluggish acceleration.

The engine may run erratically, with backfiring and stalling; it may also take longer to accelerate or shift gears due to a faulty MAP sensor.

It may also be challenging to maintain a steady speed or keep up with traffic when accelerating from a stop.

4. Strong smell of gasoline 

When a Harley MAP sensor fails, one of the most noticeable symptoms is an overpowering smell of gasoline from the engine compartment.

This powerful smell can be caused by a number of issues, including a faulty MAP sensor. 

It can cause the fuel-air mix to become unbalanced, resulting in too much gas entering the engine and being burned off.

The result is a strong odor of gasoline emanating from the motorcycle’s exhaust system.

5. Lack of power

When Map fails, the engine cannot accurately measure intake air volume and cannot adjust fuel delivery accordingly.

As a result, you may notice a significant decrease in power output and acceleration compared to how your bike performed.

6. Hard starting  

When the MAP sensor is not functioning correctly, it can cause fuel delivery and ignition timing to be off, leading to difficulty starting the engine.

This symptom is often accompanied by a low idle, rough running, or stalling when coming to a stop.

The engine may also experience misfiring, hesitation, and jerking while accelerating or cruising.

7. Overheating 

When the MAP sensor fails, resulting in unburned fuel entering the combustion chamber.

This unburned fuel generates more heat in the chamber than normal, resulting in the engine quickly reaching dangerously high temperatures and potential damage to components. 

In extreme cases, this failure can lead to engine seizure or catastrophic failure.

In order to prevent such issues, it’s important to keep an eye on your engine temperature and address any signs of abnormal or unexpected heating.

8. Backfiring through the intake 

The backfiring can be loud and disruptive and may indicate an issue with your vehicle’s fuel system’s MAP sensor or other components.

In order to diagnose this problem, you should take your vehicle to a certified mechanic for inspection.

They can determine if there is an issue with your MAP sensor or another component of your motorcycle fuel system.


What are the most common symptoms of a failed MAP sensor?

A failed MAP sensor can have several symptoms; the most common symptoms.

Include decreased fuel efficiency, decreased engine performance or acceleration, increased exhaust emissions, stalling or rough idling, and a check engine light illuminating the dashboard.

Sometimes, an issue with the MAP sensor may cause the engine to run rich or lean. Running rich will cause black smoke from the exhaust and an increase in fuel consumption.

How do I know if my MAP sensor is bad?

A bad MAP sensor will produce engine symptoms such as poor performance, rough idle, stalling, difficulty starting, and poor fuel economy.

In order to determine if your MAP sensor is bad, you should perform a few basic tests.

First, you should use a scan tool with live data functionality to check the MAP sensor for accurate readings.

You can also perform a ‘key on engine off’ test, which involves disconnecting and reconnecting the MAP sensor electrical connector.

How do you test a Harley MAP sensor?

Testing the Harley MAP sensor requires that you have an understanding of how the sensor works.

In order to test the Harley MAP sensor, you will need a diagnostic tool such as an oscilloscope or multimeter.

Connect this to both electrical connectors on the MAP sensor and turn on your engine.

If your Harley has an electronically controlled fuel injection system, you can check for a 5V reference signal from within your ECU.

Next, rev up your Harley while watching the readings from the diagnostic device for any sudden voltage drops; dips below 4V may indicate a faulty connection or worn-out wiring harness between the MAP sensor and ECU.

Wrapping Up 

These are the most common failure symptoms of the Harley Map failure.

  • Misfires 
  • Poor fuel economy
  • Slow acceleration 
  • Strong smell of gasoline 
  • Lack of power
  • Hard starting  
  • Overheating 
  • Backfiring through the intake 

Now I’d like to hear from you!

Do you still need further information about the failure symptoms of the Harley Map?

Let me know in the comment.

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