1998 DODGE RAM 1500 Trans temp

EXCESSIVE WHITE SMOKE
POSSIBLE CAUSE CORRECTION
Air in fuel supply: Possible leak in fuel supply side (between
transfer pump and fuel tank module).(Refer to 14 - FUEL SYSTEM/FUEL DELIVERY/FUEL
TRANSFER PUMP - DIAGNOSIS AND TESTING).
Coolant leaking into combustion chamber. Do pressure test of cooling system (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
Diagnostic Trouble Codes (DTC's) active or multiple,
intermittent DTC's.Refer to Powertrain Diagnostic Procedures Information.
In very cold ambient temperatures, engine block heater is
malfunctioning (if equipped).(Refer to 7 - COOLING/ENGINE/ENGINE BLOCK HEATER -
REMOVAL).
Engine coolant temperature sensor malfunctioning. A DTC should have been set. Refer to Powertrain Diagnostic
Procedures Information. Also check thermostat operation
(Refer to 7 - COOLING/ENGINE/ENGINE COOLANT
THERMOSTAT - DIAGNOSIS AND TESTING).
Engine Control Module (ECM) not calibrated or has incorrect
calibration.A DTC should have been set. Refer to Powertrain Diagnostic
Procedures Information.
Fuel filter plugged. Refer to Powertrain Diagnostic Manual for fuel system testing.
Fuel grade not correct or fuel quality is poor. Temporarily change fuel brands and note condition. Change
brand if necessary.
Fuel heater element or fuel heater temperature sensor
malfunctioning. This will cause wax type build-up in fuel filter.Refer to Fuel Heater Testing (Refer to 14 - FUEL SYSTEM/
FUEL DELIVERY/FUEL HEATER - DIAGNOSIS AND
TESTING).
Fuel injector malfunctioning. A DTC should have been set. Perform9Cylinder cutout Test9
using DRB scan tool to isolate individual cylinders. Also refer
to Powertrain Diagnostic Procedures Information and, (Refer
to 14 - FUEL SYSTEM/FUEL INJECTION/FUEL INJECTOR -
DIAGNOSIS AND TESTING).
Fuel injector hold-downs loose. Torque to specifications.
Fuel injector protrusion not correct. Check washer (shim) at bottom of fuel injector for correct
thickness. (Refer to 14 - FUEL SYSTEM/FUEL INJECTION/
FUEL INJECTOR - INSTALLATION)
Fuel injection pump malfunctioning. A DTC should have been set. Refer to Powertrain Diagnostic
Procedures Information.
Fuel supply side restriction to transfer pump. Refer to Powertrain Diagnostic Manual for fuel system testing.
Fuel transfer (lift) pump malfunctioning. A DTC may have been set. Refer to Powertrain Diagnostic
Procedures Information.
Intake/Exhaust valve adjustments not correct (too tight). (Refer to 9 - ENGINE/CYLINDER HEAD/INTAKE/EXHAUST
VALVES & SEATS - STANDARD PROCEDURE).
Intake manifold air temperature sensor malfunctioning. A DTC should have been set. Refer to Powertrain Diagnostic
Procedures Information.
Intake manifold heater circuit not functioning correctly in cold
weather.A DTC should have been set. Refer to Powertrain Diagnostic
Procedures Information. Also check heater elements for
correct operation.
Intake manifold heater elements not functioning correctly in
cold weather.A DTC should have been set if heater elements are
malfunctioning. Refer to Powertrain Diagnostic Procedures
Information.
Internal engine damage (scuffed cylinder). Analyze engine oil and inspect oil filter to locate area of
probable damage.
Restriction in fuel supply side of fuel system. Refer to Powertrain Diagnostic Manual for fuel system testing.
DRENGINE 5.9L DIESEL 9 - 237
ENGINE 5.9L DIESEL (Continued)

DIAGNOSIS AND TESTING - CYLINDER
COMPRESSION/LEAKAGE TESTS
CYLINDER COMPRESSION PRESSURE
The results of a cylinder compression pressure test
can be utilized to diagnose several engine malfunc-
tions.
Ensure batteries are completely charged and the
engine starter motor is in good operating condition.
Otherwise, the indicated compression pressures may
not be valid for diagnostic purposes.
(1) Disconnect the fuel inlet line to the fuel trans-
fer pump. Plug the fuel line from the fuel tank.
(2) Start the engine and idle until the engine stalls
(runs out of fuel).
(3) Disconnect all three injector wire harness con-
nectors at the rocker housing.
(4) Remove the breather cover and cylinder head
cover.
(5) Remove the high pressure fuel line between the
cylinder head and fuel rail for the cylinder to be
tested. Use tool# 9011 to cap this fuel rail on the cyl-
inder being tested.
(6) Remove the exhaust rocker lever.
(7) Use Tool 9010 to remove the injector and cop-
per sealing washer.
(8) Install the exhaust rocker lever and torque to
36 N´m (27 ft. lbs.).
(9) Cover the remaining rocker levers with clean
shop towels to prevent any oil splatter under the
hood.
(10) Place a rag over the compression test tool fit-
ting. Crank the engine for 2±3 seconds to purge any
fuel that may have drained into the cylinder when
the injector was removed.
(11) Connect the compression test gauge.
(12) Crank the engine for 5 seconds and record the
pressure reading. Repeat this step three times and
calculate the average of the three readings.
NOTE: The minimum cylinder pressure is 350 psi.
Cylinder pressure should be within 20% from cylin-
der to cylinder.
(13) Combustion pressure leakage can be checked
if cylinder pressure is below the specification. Per-
form the leakage test procedure on each cylinder
according to the tester manufacturer instructions.
(14) Upon completion of the test check an erase
any engine related fault codes.
CYLINDER COMBUSTION PRESSURE LEAKAGE
The combustion pressure leakage test provides an
accurate means for determining engine condition.
Combustion pressure leakage testing will detect:²Exhaust and intake valve leaks (improper seat-
ing).
²Leaks between adjacent cylinders or into water
jacket.
²Any causes for combustion/compression pressure
loss
(1) Start and operate the engine until it attains
normal operating temperature.
(2) Remove the breather cover and cylinder head
cover.
(3) Disconnect all three injector wire harness con-
nectors at the rocker housing.
(4) Bring the cylinder to be tested to TDC.
(5) Remove the high pressure fuel line between the
cylinder head and the fuel rail for the cylinder to be
tested.
(6) Install capping Tool 9011 onto the rail.
(7) Remove the high pressure connector nut and
high pressure connector with Tool 9015.
(8) Remove the exhaust and intake rocker lever.
(9) Use Tool 9010 to remove the injector and cop-
per sealing washer.
(10) Install compression test Tool 9007 into the
injector bore.
(11) Connect the leakage tester and perform the
leakage test procedure on each cylinder according to
the tester manufacturer's instructions.
(12) Upon completion of the test check and erase
any engine related fault codes.
STANDARD PROCEDURE
STANDARD PROCEDURE - FORM-IN-PLACE
GASKETS AND SEALERS
There are numerous places where form-in-place
gaskets are used on the engine. Care must be taken
when applying form-in-place gaskets to assure
obtaining the desired results.Do not use form-in-
place gasket material unless specified.Bead size,
continuity, and location are of great importance. Too
thin a bead can result in leakage while too much can
result in spill-over which can break off and obstruct
fluid feed lines. A continuous bead of the proper
width is essential to obtain a leak-free gasket.
There are numerous types of form-in-place gasket
materials that are used in the engine area. Mopart
Engine RTV GEN II, MopartATF-RTV, and Mopart
Gasket Maker gasket materials, each have different
properties and can not be used in place of the other.
MOPARtENGINE RTV GEN II
MopartEngine RTV GEN II is used to seal com-
ponents exposed to engine oil. This material is a spe-
cially designed black silicone rubber RTV that
retains adhesion and sealing properties when
exposed to engine oil. Moisture in the air causes the
DRENGINE 5.9L DIESEL 9 - 239
ENGINE 5.9L DIESEL (Continued)

material to cure. This material is available in three
ounce tubes and has a shelf life of one year. After one
year this material will not properly cure. Always
inspect the package for the expiration date before
use.
MOPARtATF RTV
MopartATF RTV is a specifically designed black
silicone rubber RTV that retains adhesion and seal-
ing properties to seal components exposed to auto-
matic transmission fluid, engine coolants, and
moisture. This material is available in three ounce
tubes and has a shelf life of one year. After one year
this material will not properly cure. Always inspect
the package for the expiration date before use.
MOPARtGASKET MAKER
MopartGasket Maker is an anaerobic type gasket
material. The material cures in the absence of air
when squeezed between two metallic surfaces. It will
not cure if left in the uncovered tube. The anaerobic
material is for use between two machined surfaces.
Do not use on flexible metal flanges.
MOPARtGASKET SEALANT
MopartGasket Sealant is a slow drying, perma-
nently soft sealer. This material is recommended for
sealing threaded fittings and gaskets against leakage
of oil and coolant. Can be used on threaded and
machined parts under all temperatures. This mate-
rial is used on engines with multi-layer steel (MLS)
cylinder head gaskets. This material also will pre-
vent corrosion. MopartGasket Sealant is available in
a 13 oz. aerosol can or 4oz./16 oz. can w/applicator.
FORM-IN-PLACE GASKET AND SEALER
APPLICATION
Assembling parts using a form-in-place gasket
requires care but it's easier than using precut gas-
kets.
MopartGasket Maker material should be applied
sparingly 1 mm (0.040 in.) diameter or less of sealant
to one gasket surface. Be certain the material sur-
rounds each mounting hole. Excess material can eas-
ily be wiped off. Components should be torqued in
place within 15 minutes. The use of a locating dowel
is recommended during assembly to prevent smear-
ing material off the location.
MopartEngine RTV GEN II or ATF RTV gasket
material should be applied in a continuous bead
approximately 3 mm (0.120 in.) in diameter. All
mounting holes must be circled. For corner sealing, a
3.17 or 6.35 mm (1/8 or 1/4 in.) drop is placed in the
center of the gasket contact area. Uncured sealant
may be removed with a shop towel. Components
should be torqued in place while the sealant is still
wet to the touch (within 10 minutes). The usage of a
locating dowel is recommended during assembly to
prevent smearing material off the location.MopartGasket Sealant in an aerosol can should be
applied using a thin, even coat sprayed completely
over both surfaces to be joined, and both sides of a
gasket. Then proceed with assembly. Material in a
can w/applicator can be brushed on evenly over the
sealing surfaces. Material in an aerosol can should be
used on engines with multi-layer steel gaskets.
STANDARD PROCEDURE - REPAIR DAMAGED
OR WORN THREADS
CAUTION: Be sure that the tapped holes maintain
the original center line.
Damaged or worn threads can be repaired. Essen-
tially, this repair consists of:
²Drilling out worn or damaged threads.
²Tapping the hole with a special Heli-Coil Tap, or
equivalent.
²Installing an insert into the tapped hole to bring
the hole back to its original thread size.
STANDARD PROCEDUREÐHYDROSTATIC
LOCK
CAUTION: DO NOT use the starter motor to rotate
the crankshaft. Severe damage could occur.
When an engine is suspected of hydrostatic lock
(regardless of what caused the problem), follow the
steps below.
(1) Disconnect the negative cable(s) from the bat-
tery.
(2) Inspect air cleaner, induction system, and
intake manifold to ensure system is dry and clear of
foreign material.
(3) Place a shop towel around the fuel injectors to
catch any fluid that may possibly be under pressure
in the cylinder head. Remove the fuel injectors (Refer
to 14 - FUEL SYSTEM/FUEL INJECTION/FUEL
INJECTOR - REMOVAL).
(4) With all injectors removed, rotate the crank-
shaft using the crankshaft barring tool (PN 7471±B).
(5) Identify the fluid in the cylinders (coolant, fuel,
oil, etc.).
(6) Be sure all fluid has been removed from the
cylinders.
(7) Repair engine or components as necessary to
prevent this problem from occurring again.
(8) Squirt a small amount of engine oil into the
cylinders to lubricate the walls. This will prevent
damage on restart.
(9) Install fuel injectors (Refer to 14 - FUEL SYS-
TEM/FUEL INJECTION/FUEL INJECTOR -
INSTALLATION).
9 - 240 ENGINE 5.9L DIESELDR
ENGINE 5.9L DIESEL (Continued)

LUBRICATION
DESCRIPTION
NOTE: Refer to (Fig. 105) and (Fig. 106) for circuit
illustrations.
A gear driven gerotor type oil pump is mounted
behind the front gear cover in the lower right portion
on the engine.
OPERATION
A gerotor style oil pump draws oil from the crank-
case through the suction tube and delivers it through
the block where it enters the oil cooler cover and
pressure regulator valve. When oil pressure exceeds
517 kPa (75 PSI), the valve opens exposing the dump
port, which routes excess oil back to the oil pump.
At the same time, oil is directed to a cast in pas-
sage in the oil cooler cover, leading to the oil cooler
element. As the oil travels through the element
plates, it is cooled by engine coolant traveling past
the outside of the plates. It is then routed to the oil
filter head and through a full flow oil filter. If a
plugged filter is encountered, the filter by-pass valve
opens, allowing unfiltered oil to lubricate the engine.
This condition can be avoided by frequent oil and fil-
ter changes, per the maintenance schedules found in
the owners manual. The by-pass valve is calibrated
to open when it sees a pressure drop of more than
345 kPa (50 psi) across the oil filter.
The oil filter head then divides the oil between the
engine and the turbocharger. The turbocharger
receives filtered, cooled and pressurized oil through a
supply line from the filter head. The oil lubricates
the turbocharger and returns to the pan by way of a
drain tube connecting the bottom of the turbocharger
to a pressed in tube in the cylinder block.
Oil is then carried across the block to an angle
drilling which intersects the main oil rifle. The main
oil rifle runs the length of the block and delivers oil
to the crankshaft main journals and valve train. Oil
travels to the crankshaft through a series of transfer
drillings (one for each main bearing) and lubricates a
groove in the main bearing upper shell. From there
another drilling feeds the camshaft main journals.The saddle jet piston cooling nozzles are also sup-
plied by the main bearing upper shell. J-jet piston
cooling nozzles are supplied by a separate oil rifle.
Plugs are used in place of saddle jets when J-jets are
used. J-jet hole locations are plugged when saddle jet
cooling nozzles are used. Crankshaft internal cross-
drillings supply oil to the connecting rod journals.
Another series of transfer drillings intersecting the
main oil rifle supply the valve train components. Oil
travels up the drilling, through a hole in the head
gasket, and through a drilling in the cylinder head
(one per cylinder), where it enters the rocker arm
pedestal and is divided between the intake and
exhaust rocker arm. Oil travels up and around the
rocker arm mounting bolt, and lubricates the rocker
shaft by cross drillings that intersect the mounting
bolt hole. Grooves at both ends of the rocker shaft
supply oil through the rocker arm where the oil trav-
els to the push rod and socket balls (Fig. 105) and
(Fig. 106).
DIAGNOSIS AND TESTINGÐENGINE OIL
PRESSURE
(1) Remove the 1/8 npt plug from the top of the oil
filter housing.
(2) Install Oil Pressure Line and Gauge Tool
C-3292 with a suitable adapter.
(3) Start engine and warm to operating tempera-
ture.
(4) Record engine oil pressure and compare with
engine oil pressure chart.
CAUTION: If engine oil pressure is zero at idle, DO
NOT RUN THE ENGINE.
Engine Oil Pressure (MIN)
At Idle 68.9 kPa (10 psi)
At 2500 rpm 206.9 kPa (30 psi)
If minimum engine oil pressure is below these
ranges, (Refer to 9 - ENGINE - DIAGNOSIS AND
TESTING).
(5) Remove oil pressure gauge and install the 1/8
npt plug.
DRENGINE 5.9L DIESEL 9 - 289

OIL COOLER & LINES
CLEANING
CLEANING AND INSPECTION
Clean the sealing surfaces.
Apply 483 kPa (70 psi) air pressure to the element
to check for leaks. If the element leaks, replace the
element.
OIL FILTER
REMOVAL
(1) Clean the area around the oil filter head.
Remove the filter from below using a cap-style filter
wrench.
(2) Clean the gasket surface of the filter head. The
filter canister O-Ring seal can stick on the filter
head. Make sure it is removed.
INSTALLATION
(1) Fill the oil filter element with clean oil before
installation. Use the same type oil that will be used
in the engine.
(2) Apply a light film of lubricating oil to the seal-
ing surface before installing the filter.
CAUTION: Mechanical over-tightening may distort
the threads or damage the filter element seal.
(3) Install the filter until it contacts the sealing
surface of the oil filter adapter. Tighten filter an
additional
1¤2turn.
OIL PAN
REMOVAL
(1) Disconnect the battery negative cables.
(2) Install engine support fixture # 8534.
(3) Raise vehicle on hoist.
(4) Disconnect starter cables from starter motor.
(5) Remove transmission and transfer case (if
equipped).
(6) Remove flywheel or flexplate.
(7) Remove starter motor (Refer to 8 - ELECTRI-
CAL/STARTING/STARTER MOTOR - REMOVAL)
and transmission adapter plate assembly.
WARNING: HOT OIL CAN CAUSE PERSONAL
INJURY.
(8) Drain the engine oil (Refer to 9 - ENGINE/LU-
BRICATION/OIL - STANDARD PROCEDURE).(9) Install the oil pan drain plug if sealing surface
is not damaged and tighten to 50 N´m (37 ft. lbs.)
torque.
(10) Remove oil pan bolts, break the pan to block
seal, and lower pan slightly and remove oil suction
tube fasteners.
(11) Remove oil pan and suction tube.
CLEANING
Remove all gasket material from the oil pan and
cylinder block sealing surfaces. Extra effort may be
required around T-joint areas. Clean oil pan and
flush suction tube with a suitable solvent.
INSPECTION
Inspect the oil pan, suction tube, and tube braces
for cracks and damage. Replace any defective compo-
nent. Inspect the oil drain plug and drain hole
threads. Inspect the oil pan sealing surface for
straightness. Repair any minor imperfections with a
ball-peen hammer. Do not attempt to repair an oil
pan by welding.
INSTALLATION
(1) Fill the T-joint between the pan rail/gear hous-
ing and pan rail/rear seal retainer with sealant. Use
MopartSilicone Rubber Adhesive Sealant or equiva-
lent.
(2) Place suction tube in oil pan and guide them
into place. Using a new tube to block gasket, install
and tighten the suction tube bolts by hand. Starting
with the oil pump inlet bolts, tighten the bolts to 24
N´m (18 ft. lbs.) torque. Tighten the remaining tube
brace bolts to 43 N´m (32 ft. lbs.) torque.
(3) Starting in the center and working outward,
tighten the oil pan bolts to 28 N´m (21 ft. lbs.)
torque.
(4) Install the flywheel housing assembly with the
starter motor attached and tighten bolts to 77 N´m
(57 ft. lbs.) torque.
(5) Connect starter motor cables.
(6) Install the flywheel or flexplate. Torque to 137
N´m (101 ft. lbs.).
(7) Install transmission and transfer case (if
equipped).
(8) Lower vehicle.
(9) Remove the engine support fixture # 8534.
(10) Install battery negative cables.
(11) Fill the crankcase with new engine oil.
(12) Start engine and check for leaks. Stop engine,
check oil level, and adjust, if necessary.
DRENGINE 5.9L DIESEL 9 - 293

OPERATION
Exhaust gas pressure and energy drive the tur-
bine, which in turn drives a centrifugal compressor
that compresses the inlet air, and forces the air into
the engine through the charge air cooler and plumb-
ing. Since heat is a by-product of this compression,
the air must pass through a charge air cooler to cool
the incoming air and maintain power and efficiency.
Increasing air flow to the engine provides:
²Improved engine performance
²Lower exhaust smoke density
²Improved operating economy
²Altitude compensation
²Noise reduction.
The turbocharger also uses a wastegate (Fig. 16),
which regulates intake manifold air pressure and
prevents over boosting at high engine speeds. When
the wastegate valve is closed, all of the exhaust gases
flow through the turbine wheel. As the intake mani-
fold pressure increases, the wastegate actuator opens
the valve, diverting some of the exhaust gases away
from the turbine wheel. This limits turbine shaft
speed and air output from the impeller.
The turbocharger is lubricated by engine oil that is
pressurized, cooled, and filtered. The oil is delivered
to the turbocharger by a supply line that is tapped
into the oil filter head. The oil travels into the bear-
ing housing, where it lubricates the shaft and bear-
ings (Fig. 17). A return pipe at the bottom of the
bearing housing, routes the engine oil back to the
crankcase.
The most common turbocharger failure is bearing
failure related to repeated hot shutdowns with inad-
equate ªcool-downº periods. A sudden engine shut
down after prolonged operation will result in the
transfer of heat from the turbine section of the tur-
bocharger to the bearing housing. This causes the oil
to overheat and break down, which causes bearing
and shaft damage the next time the vehicle is
started.
Letting the engine idle after extended operation
allows the turbine housing to cool to normal operat-
ing temperature. The following chart should be used
as a guide in determining the amount of engine idle
time required to sufficiently cool down the turbo-
charger before shut down, depending upon the type
of driving and the amount of cargo.
Fig. 16 Wastegate Operation
1 - SIGNAL LINE
2 - EXHAUST BYPASS VALVE
3 - WASTEGATE
4 - EXHAUST
5 - TURBINE
DREXHAUST SYSTEM 11 - 13
TURBOCHARGER (Continued)

(9) Remove the turbocharger and gasket from the
exhaust manifold.
(10) If the turbocharger is not to be installed
immediately, cover the opening to prevent material
from entering into the manifold.
(11) If replacing the turbocharger, transfer the tur-
bocharger oil supply fitting to the new assembly.
Tighten fitting to 36 N´m (27 ft. lbs.).
(12) Clean and inspect the sealing surface.
CAUTION: The turbocharger is only serviced as an
assembly. Do not attempt to repair the turbocharger
as turbocharger and/or engine damage can result.
CLEANING
WARNING: To prevent damage or personal injury,
do not use a combustable cleaner to clean the tur-
bocharger.
Clean the turbocharger and exhaust manifold
mounting surfaces with a suitable scraper.
INSPECTION
Visually inspect the turbocharger and exhaust
manifold gasket surfaces. Replace stripped or eroded
mounting studs.
(1) Visually inspect the turbocharger for cracks.
The following cracks are NOT acceptable:
²Cracks in the turbine and compressor housing
that go completely through.
²Cracks in the mounting flange that are longer
than 15 mm (0.6 in.).
²Cracks in the mounting flange that intersect
bolt through-holes.
²Two (2) Cracks in the mounting flange that are
closer than 6.4 mm (0.25 in.) together.
(2) Visually inspect the impeller and compressor
wheel fins for nicks, cracks, or chips. Note: Some
impellers may have a factory placed paint mark
which, after normal operation, appears to be a crack.
Remove this mark with a suitable solvent to verify
that it is not a crack.
(3) Visually inspect the turbocharger compressor
housing for an impeller rubbing condition (Fig. 20).
Replace the turbocharger if the condition exists.
(4) Measure the turbocharger axial end play:
(a) Install a dial indicator as shown in (Fig. 21).
Zero the indicator at one end of travel.
(b) Move the impeller shaft fore and aft and
record the measurement. Allowable end play is
0.026 mm (0.0001 in.) MIN. and 0.127 mm (0.005
in.) MAX. If the recorded measurement falls out-
side these parameters, replace the turbocharger
assembly.(5) Measure the turbocharger bearing radial clear-
ance:
(a) Insert a narrow blade or wire style feeler
gauge between the compressor wheel and the hous-
ing (Fig. 22).
(b) Gently push the compressor wheel toward
the housing and record the clearance.
(c) With the feeler gauge in the same location,
gently push the compressor wheel away from the
housing and again record the clearance.
(d) Subtract the smaller clearance from the
larger clearance. This is the radial bearing clear-
ance.
(e) Allowable radial bearing clearance is 0.33
mm (0.013 in.) MIN. and 0.50 mm (0.020 in.) MAX.
If the recorded measurement falls outside these
specifications, replace the turbocharger assembly.
INSTALLATION
(1) Install the turbocharger. Apply anti-seize to the
studs and then tighten the turbocharger mounting
nuts to 43 N´m (32 ft. lbs.) torque.
Fig. 20 Inspect Compressor Housing for Impeller
Rubbing Condition
Fig. 21 Measure Turbocharger Axial End Play
DREXHAUST SYSTEM 11 - 15
TURBOCHARGER (Continued)

²Engine load
²Injector pulse-width
²Spark-advance programs
²Shift-point strategies (certain automatic trans-
missions only)
²Idle speed
²Decel fuel shutoff
The MAP sensor signal is provided from a single
piezoresistive element located in the center of a dia-
phragm. The element and diaphragm are both made
of silicone. As manifold pressure changes, the dia-
phragm 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 pres-
sure 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 usu-
ally between 4.6 volts at sea level to as low as 0.3
volts at 26 in. of Hg. Barometric pressure is the pres-
sure 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 baromet-
ric pressure from what should be present for that
altitude. You should know what the average pressure
and corresponding barometric pressure is for your
area.
REMOVAL
3.7L V-6
The Manifold Absolute Pressure (MAP) sensor is
mounted into the front of the intake manifold (Fig.
21). An o-ring is used to seal the sensor to the intake
manifold (Fig. 22).
(1) Disconnect electrical connector at sensor.
(2) Clean area around MAP sensor.
(3) Remove 2 sensor mounting screws.
(4) Remove MAP sensor from intake manifold.
(5) Check condition of sensor o-ring (Fig. 22).
4.7L V-8
The MAP sensor is located on the front of the
intake manifold (Fig. 23). An o-ring seals the sensor
to the intake manifold.
(1) Disconnect electrical connector at sensor.
(2) Clean area around MAP sensor.
(3) Remove 2 sensor mounting bolts (Fig. 23).(4) Remove MAP sensor from intake manifold.
(5) Check condition of sensor o-ring (Fig. 22).
Fig. 21 MAP SENSOR - 3.7L V-6
1 - MOUNTING SCREWS
2 - MAP SENSOR
3 - ECT SENSOR
4 - FRONT OF INTAKE MANIFOLD
Fig. 22 MAP SENSOR O-RING 3.7L / 4.7L
1 - MAP SENSOR
2 - O-RING
DRFUEL INJECTION - GAS 14 - 33
MAP SENSOR (Continued)