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Discussion Starter #161 (Edited)
Map Sensor cleaning or replacing 3.7 dodge nitro


Jan 25, 2021

If the MAP sensor goes bad, the ECM can't accurately calculate engine load, which means the air-fuel ratio will become either too rich (more fuel) or too lean (less fuel). ... This leads to excessive fuel consumption, poor fuel economy, and possibly detonation. Lack of Power.

7 Symptoms of a Broken MAP Sensor



By
Benjamin Jerew




Updated May 31, 2019

In modern engines, the engine control module (ECM) measures or calculates air flow via either a mass air flow (MAF) or manifold absolute pressure (MAP) sensor. Turbocharged engines may use both, but naturally-aspirated engines typically use one or the other. If the MAP sensor is failing or broken, the ECM — and thus, the engine — can't function properly. By maintaining and repairing your MAP sensor, you'll keep your engine running smoothly.

How a MAP Sensor Works
MAP sensor in a car engine highlighted in dark red.

This MAP sensor is mounted directly to the intake manifold, but others might be connected by a hose.

The ECM uses MAP sensor data to run crucial calculations, such as engine load, fuel injector pulse, and spark advance. When at rest, the MAP sensor reads atmospheric pressure at sea level (29.93 in. Hg). Because atmospheric pressure varies with weather and altitude, the ECM calculates this “zero” point just before the engine starts, fine-tuning spark and fuel injection mapping from that point.

When idling, intake pressure usually ranges from 16-22 in. Hg. Because this is lower than atmospheric pressure, air rushes into the intake. When the driver uses the engine to brake, pressure can go as low as 10 in. Hg. Upon accelerating, however, the open throttle body allows air to rush in faster, increasing pressure in the intake. At wide-open throttle, intake and atmospheric pressure are nearly equal.


Signs of a Broken MAP Sensor
Check engine light in a late-model car.

MAP sensor problems could trigger a DTC and check engine light.


MAP sensors fail by getting clogged, contaminated, or damaged. Sometimes, engine heat “overcooks” the MAP sensor's electronics or cracks vacuum lines. If the MAP sensor goes bad, the ECM can’t accurately calculate engine load, which means the air-fuel ratio will become either too rich (more fuel) or too lean (less fuel).

So, how will you know that your MAP sensor is going bad? Here are the key problems to look out for:
  1. Poor Fuel Economy. If the ECM is reading low or no vacuum, it assumes the engine is at high load, so it dumps in more fuel and advances spark timing. This leads to excessive fuel consumption, poor fuel economy, and possibly detonation.
  2. Lack of Power. If the ECM is reading high vacuum, it assumes the engine load is low, so it cuts fuel injection and retards spark timing. On the one hand, fuel consumption will go down, which seems like a good thing. However, if too little fuel is consumed, the engine may lack power for acceleration and passing.
  3. Failed Emissions Inspection. Because fuel injection doesn’t correspond to engine load, a broken MAP sensor can lead to an increase in harmful emissions. Excessive fuel generates higher hydrocarbon (HC) and carbon monoxide (CO) emissions, while insufficient fuel may lead to higher nitrogen oxide (NOx) emissions.
  4. Rough Idle. Insufficient fuel injection starves the engine for fuel, leading to rough idling and perhaps even random cylinder misfiring.
  5. Hard Starting. Similarly, an excessively rich or lean mix makes the engine hard to start. If you can only start the engine when your foot is on the accelerator, you probably have a MAP sensor problem.
  6. Hesitation or Stalling. When starting from a stop or trying a passing maneuver, stepping on the gas might not give you any joy, especially if the ECM is giving you a lean mixture based on faulty MAP sensor readings.
  7. Check Engine Light. Depending on the age of your vehicle, MAP sensor diagnostic trouble codes (DTC) may range from simple circuit, or sensor faults, to correlation, or range faults. A dead MAP sensor won’t read anything, while a failing MAP sensor might give the ECM data that makes no sense, such as low engine vacuum when the throttle position sensor (TPS) and crankshaft position sensor (CKP) both show the engine at idle.


MAP Sensor Problems
Bluetooth OBD2 scan tool.

A Bluetooth OBD2 scan tool is an inexpensive but powerful tool for diagnosing all kinds of engine problems, such as a failing map sensor.

A functional MAP sensor is a critical part of the maintenance of your vehicle. If you suspect that you may have a problem with your MAP sensor, check the following elements first.
  1. Electrical. Start by checking the connector and wiring. The connector should be securely connected, and the pins should be clean and straight. Corrosion or bent pins can cause MAP sensor signal problems. Similarly, the wiring between the ECM and MAP sensor should be intact. Chafing could cause short circuits, and breaks could cause open circuits.
  2. Hose. Some MAP sensors are connected to the intake manifold by a hose. Check that the MAP sensor hose is connected and intact. Also, check that the port is free of carbon deposits or other debris, which could block the hose and lead to poor MAP sensor readings.
  3. Sensor. If the sensor is connected properly, both electrically and to the intake manifold, use a scan tool or voltage meter and vacuum gun to check MAP sensor output. You’ll have to look up a chart to measure voltage against no vacuum and full vacuum. If MAP sensor output doesn’t match the chart, it’s safe to say the sensor should be replaced.








 

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Discussion Starter #162
Dodge Nitro P0108: MAP Barometric Sensor → High Input

December 18, 2019 by Jason



P0108 is a generic OBD-II trouble code. It indicates your Dodge Nitro’s MAP (manifold absolute pressure) sensor’s voltage reading is outside of the normal operating range. The voltage is too high. It’s most commonly caused by a bad MAP sensor, wiring issue, or vacuum leak.

The MAP sensor measures the air pressure coming into your Nitro’s engine and sends that signal to the ECM. It does this by sending a voltage ranging from 1 to 5 volts. 1 volt would be idle speed. The signal should be at 5 volts whenever the vehicle is at wide open throttle. P0108 is triggered whenever the signal from this wire is MORE THAN 5 volts, which shouldn’t happen.

P0108 can also trigger if the ECM thinks the voltage coming from the MAP sensor is higher than it should be at any given time.

Dodge Nitro P0108: MAP Barometric Sensor → High Input

December 18, 2019 by Jason



P0108 is a generic OBD-II trouble code. It indicates your Dodge Nitro’s MAP (manifold absolute pressure) sensor’s voltage reading is outside of the normal operating range. The voltage is too high. It’s most commonly caused by a bad MAP sensor, wiring issue, or vacuum leak.

The MAP sensor measures the air pressure coming into your Nitro’s engine and sends that signal to the ECM. It does this by sending a voltage ranging from 1 to 5 volts. 1 volt would be idle speed. The signal should be at 5 volts whenever the vehicle is at wide open throttle. P0108 is triggered whenever the signal from this wire is MORE THAN 5 volts, which shouldn’t happen.

P0108 can also trigger if the ECM thinks the voltage coming from the MAP sensor is higher than it should be at any given time.



P0108 Dodge Nitro


P0108 Quick Facts
  • P0108 is caused when there’s too much voltage coming from the MAP sensor to the ECM.
  • Most commonly caused by a bad MAP sensor. Vacuum or wiring issue are the next most common causes.
  • Usually results in a rough running vehicle.
  • A voltage meter is required to diagnose the MAP sensor.


P0108 Symptoms: Dodge Nitro
P0108 is always going to do more than just trigger the check engine light. The MAP sensor is vital to a well running vehicle. If it’s gone bad, it’ll really affect drivability.

Here are the most common symptoms of P0108:

  • Poor Gas Mileage
  • Rough Running/Stalling Engine
  • Motor Won’t Start at All
  • Black Exhaust Smoke
  • Check Engine Light



Dodge Nitro P0108 Diagnosis


Dodge Nitro P0108 Causes + Diagnosis
When diagnosing this code, if your Nitro is running fine you should first reset the code and take the vehicle out and try to reproduce the problem. It may have just been a one time thing.


Map Sensor
The first thing that you should do is test the MAP sensor itself. A good voltmeter is necessary for this step. You can get them pretty cheap from any hardware store or Amazon. The reading from the voltmeter should be around 1 to 1.5 volts at idle. If it’s higher, you may need a new MAP sensor.

Here’s a pretty good YouTube video that shows exactly how you would go about testing the sensor:

Map Sensor Testing





Vacuum Leak
A vacuum leak is a very common reason that P0108 is triggered. If there isn’t enough vacuum going to the MAP sensor it’ll give a higher voltage reading than the operating conditions suggest should be there.

The vacuum supply to the MAP sensor could have a leak, or there could be a vacuum leak around the engine as a whole. Check all the vacuum lines on the engine. Check to see if any of them appear to be brittle, melted or cracked. If they are, replace them and see if that solves the problem.

Another place that vacuum can leak from the intake manifold. Here’s a solid article from Popular Mechanics on how to track down a vacuum leak.


Wiring Issues
The easiest thing that you can do when P0108 is triggered is check your Nitro’s wiring harness. Is it plugged in to the MAP Sensor tightly? Does it have any visible signs of damage? Follow it as far as you can and make sure. It’s going to have a ground wire. Make sure that ground is plugged in tightly. Here’s a good video on how to find a short in a vehicle.


Other
While the three causes listed above are the most common reasons P0108 shows up, there are other reasons as well. If your Nitro’s motor is worn out and isn’t producing a good vacuum anymore, that’ll cause the MAP sensor to output a higher voltage at all times and throw the code.

It’s also possible that an engine that is misfiring or has low fuel pressure can trigger this code as well. It would need to be a pretty noticeable misfire. You should also get P0300 or P030X (X representing the cylinder number of the misfire) with P0108 if misfiring was the case.


Conclusion: P0108 Nitro
While it is most likely to be the MAP sensor itself that is causing P0108 in your Dodge Nitro, properly identifying the problem can save you from purchasing and installing a sensor that you don’t need If there is anything that you would like to add, please leave a comment below. Good luck!
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