map sensor

[luis]

Is there a way/ a trick to c if u have a bad map sensor

 

[superj]

test it with a multimeter. the little 5 dollar multimeter at walmart will save you a ton of money. its a good little unit for checking basic stuff

 

[luis]

test it with a multimeter. the little 5 dollar multimeter at walmart will save you a ton of money. its a good little unit for checking basic stuff

I have one of them laying around. What will I be looking for? In what settings

 

[superj]

i believe you will check the output of the map on the resistance setting. have to get one of the other guys on here to check their manual to see what the readings should be though

 

[luis]

i believe you will check the output of the map on the resistance setting. have to get one of the other guys on here to check their manual to see what the readings should be though

Thank u for that. A buddy told me to disconnect it and see what happens. Unplugged it nothing change then plugged it in then idle drop to almost dieng then engine caught it self

 

[superj]

your map sensor helps the ecu know how much fuel to spray into the cylinder. it measures the density of the air coming into the engine. it means manifold absolute pressure sensor

 

[luis]

your map sensor helps the ecu know how much fuel to spray into the cylinder. it measures the density of the air coming into the engine. it means manifold absolute pressure sensor

So I have a bad map sensor then?

 

[superj]

not necessarily. thats why you need someone to post up the values it should be reading so you can check it

 

[mud4feet]

From my service manual......hope it helps (for an '03)

4.0L
(1) Install IAT sensor into intake manifold.
Tighten sensor to 28 N·m (20 ft. lbs.) torque.
(2) Connect electrical connector to sensor.
MAP SENSOR
DESCRIPTION
2.4L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the rear of the intake manifold with 1
screw.
4.0L
The Manifold Absolute Pressure (MAP) sensor is
attached to the side of the engine throttle body with
2 screws. The sensor is connected to the throttle body
with a rubber L-shaped fitting.
OPERATION
The MAP sensor is used as an input to the Powertrain
Control Module (PCM). It contains a silicon
based sensing unit to provide data on the manifold
vacuum that draws the air/fuel mixture into the combustion
chamber. The PCM requires this information
to determine injector pulse width and spark advance.
When manifold absolute pressure (MAP) equals
Barometric pressure, the pulse width will be at maximum.
A 5 volt reference is supplied from the PCM and
returns a voltage signal to the PCM that reflects
manifold pressure. The zero pressure reading is 0.5V
and full scale is 4.5V. For a pressure swing of 0–15
psi, the voltage changes 4.0V. To operate the sensor,
it is supplied a regulated 4.8 to 5.1 volts. Ground is
provided through the low-noise, sensor return circuit
at the PCM.
The MAP sensor input is the number one contributor
to fuel injector pulse width. The most important
function of the MAP sensor is to determine barometric
pressure. The PCM needs to know if the vehicle is
at sea level or at a higher altitude, because the air
density changes with altitude. It will also help to correct
for varying barometric pressure. Barometric
pressure and altitude have a direct inverse correlation;
as altitude goes up, barometric goes down. At
key-on, the PCM powers up and looks at MAP voltage,
and based upon the voltage it sees, it knows the
current barometric pressure (relative to altitude).
Once the engine starts, the PCM looks at the voltage
again, continuously every 12 milliseconds, and compares
the current voltage to what it was at key-on.
The difference between current voltage and what it
was at key-on, is manifold vacuum.
During key-on (engine not running) the sensor
reads (updates) barometric pressure. A normal range
can be obtained by monitoring a known good sensor.
As the altitude increases, the air becomes thinner
(less oxygen). If a vehicle is started and driven to a
very different altitude than where it was at key-on,
the barometric pressure needs to be updated. Any
time the PCM sees Wide Open Throttle (WOT), based
upon Throttle Position Sensor (TPS) angle and RPM,
it will update barometric pressure in the MAP memory
cell. With periodic updates, the PCM can make
its calculations more effectively.
The PCM uses the MAP sensor input to aid in calculating
the following:
• Manifold pressure
• Barometric pressure
• Engine load
• Injector pulse-width
• Spark-advance programs
• Shift-point strategies (certain automatic transmissions
only)
• Idle speed
• Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a diaphragm.
The element and diaphragm are both made
of silicone. As manifold pressure changes, the diaphragm
moves causing the element to deflect, which
stresses the silicone. When silicone is exposed to
stress, its resistance changes. As manifold vacuum
increases, the MAP sensor input voltage decreases
proportionally. The sensor also contains electronics
that condition the signal and provide temperature
compensation.
The PCM recognizes a decrease in manifold pressure
by monitoring a decrease in voltage from the
reading stored in the barometric pressure memory
cell. The MAP sensor is a linear sensor; meaning as
pressure changes, voltage changes proportionately.
The range of voltage output from the sensor is usually
between 4.6 volts at sea level to as low as 0.3
volts at 26 in. of Hg. Barometric pressure is the pressure
exerted by the atmosphere upon an object. At
sea level on a standard day, no storm, barometric
pressure is approximately 29.92 in Hg. For every 100
feet of altitude, barometric pressure drops 0.10 in.
Hg. If a storm goes through, it can change barometric
pressure from what should be present for that
altitude. You should know what the average pressure
and corresponding barometric pressure is for your
area.
TJ FUEL INJECTION 14 - 31
INTAKE AIR TE

 

[luis]

From my service manual......hope it helps (for an '03)

4.0L
(1) Install IAT sensor into intake manifold.
Tighten sensor to 28 N·m (20 ft. lbs.) torque.
(2) Connect electrical connector to sensor.
MAP SENSOR
DESCRIPTION
2.4L
The Manifold Absolute Pressure (MAP) sensor is
mounted into the rear of the intake manifold with 1
screw.
4.0L
The Manifold Absolute Pressure (MAP) sensor is
attached to the side of the engine throttle body with
2 screws. The sensor is connected to the throttle body
with a rubber L-shaped fitting.
OPERATION
The MAP sensor is used as an input to the Powertrain
Control Module (PCM). It contains a silicon
based sensing unit to provide data on the manifold
vacuum that draws the air/fuel mixture into the combustion
chamber. The PCM requires this information
to determine injector pulse width and spark advance.
When manifold absolute pressure (MAP) equals
Barometric pressure, the pulse width will be at maximum.
A 5 volt reference is supplied from the PCM and
returns a voltage signal to the PCM that reflects
manifold pressure. The zero pressure reading is 0.5V
and full scale is 4.5V. For a pressure swing of 0–15
psi, the voltage changes 4.0V. To operate the sensor,
it is supplied a regulated 4.8 to 5.1 volts. Ground is
provided through the low-noise, sensor return circuit
at the PCM.
The MAP sensor input is the number one contributor
to fuel injector pulse width. The most important
function of the MAP sensor is to determine barometric
pressure. The PCM needs to know if the vehicle is
at sea level or at a higher altitude, because the air
density changes with altitude. It will also help to correct
for varying barometric pressure. Barometric
pressure and altitude have a direct inverse correlation;
as altitude goes up, barometric goes down. At
key-on, the PCM powers up and looks at MAP voltage,
and based upon the voltage it sees, it knows the
current barometric pressure (relative to altitude).
Once the engine starts, the PCM looks at the voltage
again, continuously every 12 milliseconds, and compares
the current voltage to what it was at key-on.
The difference between current voltage and what it
was at key-on, is manifold vacuum.
During key-on (engine not running) the sensor
reads (updates) barometric pressure. A normal range
can be obtained by monitoring a known good sensor.
As the altitude increases, the air becomes thinner
(less oxygen). If a vehicle is started and driven to a
very different altitude than where it was at key-on,
the barometric pressure needs to be updated. Any
time the PCM sees Wide Open Throttle (WOT), based
upon Throttle Position Sensor (TPS) angle and RPM,
it will update barometric pressure in the MAP memory
cell. With periodic updates, the PCM can make
its calculations more effectively.
The PCM uses the MAP sensor input to aid in calculating
the following:
• Manifold pressure
• Barometric pressure
• Engine load
• Injector pulse-width
• Spark-advance programs
• Shift-point strategies (certain automatic transmissions
only)
• Idle speed
• Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a diaphragm.
The element and diaphragm are both made
of silicone. As manifold pressure changes, the diaphragm
moves causing the element to deflect, which
stresses the silicone. When silicone is exposed to
stress, its resistance changes. As manifold vacuum
increases, the MAP sensor input voltage decreases
proportionally. The sensor also contains electronics
that condition the signal and provide temperature
compensation.
The PCM recognizes a decrease in manifold pressure
by monitoring a decrease in voltage from the
reading stored in the barometric pressure memory
cell. The MAP sensor is a linear sensor; meaning as
pressure changes, voltage changes proportionately.
The range of voltage output from the sensor is usually
between 4.6 volts at sea level to as low as 0.3
volts at 26 in. of Hg. Barometric pressure is the pressure
exerted by the atmosphere upon an object. At
sea level on a standard day, no storm, barometric
pressure is approximately 29.92 in Hg. For every 100
feet of altitude, barometric pressure drops 0.10 in.
Hg. If a storm goes through, it can change barometric
pressure from what should be present for that
altitude. You should know what the average pressure
and corresponding barometric pressure is for your
area.
TJ FUEL INJECTION 14 - 31
INTAKE AIR TE

Thank you that help me a lot.