Chrysler New Yorker. Manual — part 62

DIAGNOSIS AND TESTING

IGNITION TIMING PROCEDURE

The engines for this vehicle, use a fixed ignition

system. The PCM regulates ignition timing. Basic
ignition timing is not adjustable.

CAMSHAFT POSITION SENSOR AND CRANKSHAFT
POSITION SENSOR

The output voltage of a properly operating cam-

shaft position sensor or crankshaft position sensor
switches from high (5.0 volts) to low (0.3 volts). By
connecting an Moper Diagonostic System (MDS) and
engine analyzer to the vehicle, technicians can view
the square wave pattern.

ENGINE COOLANT TEMPERATURE SENSOR

Refer to Group 14, Fuel System for Diagnosis and

Testing.

INTAKE AIR TEMPERATURE SENSOR

Refer to Group 14, Fuel System, for Diagnosis and

Testing.

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR
TEST

Refer to Group 14, Fuel System for Diagnosis and

Testing.

THROTTLE POSITION SENSOR

To perform a complete test of the this sensor and

its circuitry, refer to the DRB scan tool and appropri-
ate Powertrain Diagnostics Procedures manual. To
test the throttle position sensor only, refer to the fol-
lowing:

The Throttle Position Sensor (TPS) can be tested

with a digital voltmeter (DVM). The center terminal
of the sensor is the output terminal. One of the other
terminals is a 5 volt supply and the remaining ter-
minal is ground.

Connect the DVM between the center and sensor

ground terminal. Refer to Group 8W - Wiring Dia-
grams for correct pinout.

With the ignition switch in the ON position, check

the output voltage at the center terminal wire of the
connector. Check the output voltage at idle and at
Wide-Open-Throttle (WOT). At idle, TPS output volt-
age should be approximately 0.38 volts to 1.2 volts.
At wide open throttle, TPS output voltage should be
approximately 3.1 volts to 4.4 volts. The output volt-
age should gradually increase as the throttle plate
moves slowly from idle to WOT.

Check for spread terminals at the sensor and PCM

connections before replacing the TPS.

SPARK PLUG CONDITION

NORMAL OPERATING CONDITIONS

The few deposits present will be probably light tan

or slightly gray in color with most grades of commer-
cial gasoline (Fig. 19). There will not be evidence of
electrode burning. Gap growth will not average more
than approximately 0.025 mm (.001 in) per 1600 km
(1000 miles) of operation for non platinum spark
plugs. Non-platnium spark plugs that have normal
wear can usually be cleaned, have the electrodes filed
and regapped, and then reinstalled.

CAUTION: Never attempt to file the electrodes or
use a wire brush for cleaning platinum spark plugs.
This would damage the platinum pads which would
shorten spark plug life.

Some fuel refiners in several areas of the United

States have introduced a manganese additive (MMT)
for unleaded fuel. During combustion, fuel with MMT
may coat the entire tip of the spark plug with a rust
colored deposit. The rust color deposits can be misdi-
agnosed as being caused by coolant in the combustion
chamber. Spark plug performance is not affected by
MMT deposits.

COLD FOULING (CARBON FOULING)

Cold fouling is sometimes referred to as carbon

fouling because the deposits that cause cold fouling
are basically carbon (Fig. 19). A dry, black deposit on
one or two plugs in a set may be caused by sticking
valves or misfire conditions. Cold (carbon) fouling of
the entire set may be caused by a clogged air cleaner.

Cold fouling is normal after short operating peri-

ods. The spark plugs do not reach a high enough
operating temperature during short operating peri-
ods. Replace carbon fouled plugs with new
spark plugs.

Fig. 19 Normal Operation and Cold (Carbon) Fouling

8D - 8

IGNITION SYSTEM

300M

FUEL FOULING

A spark plug that is coated with excessive wet fuel

is called fuel fouled. This condition is normally
observed during hard start periods. Clean fuel
fouled spark plugs with compressed air and
reinstall them in the engine.

OIL FOULING

A spark plug that is coated with excessive wet oil

is oil fouled. In older engines, wet fouling can be
caused by worn rings or excessive cylinder wear.
Break-in fouling of new engines may occur before
normal oil control is achieved. Replace oil fouled
spark plugs with new ones.

OIL OR ASH ENCRUSTED

If one or more plugs are oil or ash encrusted, eval-

uate the engine for the cause of oil entering the com-
bustion chambers (Fig. 20). Sometimes fuel additives
can cause ash encrustation on an entire set of spark
plugs. Ash encrusted spark plugs can be cleaned
and reused.

HIGH SPEED MISS

When replacing spark plugs because of a high

speed miss condition; wide open throttle opera-
tion should be avoided for approximately 80 km
(50 miles) after installation of new plugs. This
will allow deposit shifting in the combustion chamber
to take place gradually and avoid plug destroying
splash fouling shortly after the plug change.

ELECTRODE GAP BRIDGING

Loose deposits in the combustion chamber can

cause electrode gap bridging. The deposits accumu-
late on the spark plugs during continuous stop-
and-go

driving.

When

the

engine

is

suddenly

subjected to a high torque load, the deposits partially
liquefy and bridge the gap between the electrodes
(Fig. 21). This short circuits the electrodes. Spark
plugs

with

electrode

gap

bridging

can

be

cleaned and reused.

SCAVENGER DEPOSITS

Fuel scavenger deposits may be either white or yel-

low (Fig. 22). They may appear to be harmful, but
are a normal condition caused by chemical additives
in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Notice that accumula-
tion on the ground electrode and shell area may be
heavy but the deposits are easily removed. Spark
plugs with scavenger deposits can be consid-
ered normal in condition, cleaned and reused.

Fig. 20 Oil or Ash Encrusted

Fig. 21 Electrode Gap Bridging

Fig. 22 Scavenger Deposits

300M

IGNITION SYSTEM

8D - 9

DIAGNOSIS AND TESTING (Continued)

CHIPPED ELECTRODE INSULATOR

A chipped electrode insulator usually results from

bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,
severe detonation also can separate the insulator
from the center electrode (Fig. 23). Spark plugs
with

chipped

electrode

insulators

must

be

replaced.

PREIGNITION DAMAGE

Excessive combustion chamber temperature can

cause preignition damage. First, the center electrode
dissolves and the ground electrode dissolves some-
what later (Fig. 24). Insulators appear relatively
deposit free. Determine if the spark plugs are the
correct type, as specified on the VECI label, or if
other operating conditions are causing engine over-
heating.

SPARK PLUG OVERHEATING

Overheating is indicated by a white or gray center

electrode insulator that also appears blistered (Fig.
25). The increase in electrode gap will be consider-

ably in excess of 0.001 in per 1000 miles of operation.
This suggests that a plug with a cooler heat range
rating should be used. Over advanced ignition tim-
ing, detonation and cooling system malfunctions also
can cause spark plug overheating.

REMOVAL AND INSTALLATION

POWERTRAIN CONTROL MODULE (PCM)

The PCM engine control strategy prevents reduced

idle speeds until after the engine operates for 320 km
(200 miles). If the PCM is replaced after 320 km (200
miles) of usage, update the mileage and vehicle iden-
tification number (VIN) in the new PCM. Use the
DRB scan tool to change the mileage and VIN in the
PCM. If this step is not done a Diagnostic Trouble
Code (DTC) may be set. Refer to the appropriate
Powertrain Diagnostic Manual and the DRB scan
tool.

REMOVAL

To avoid possible voltage spike damage to PCM,

ignition key must be off, and the negative battery
cable must be disconnected before unplugging the
PCM connectors. Note radio programs.

(1) Remove speed control servo and bracket and

reposition out of the way (Fig. 26).

(2) Reposition wiring harness out of the way.
(3) Remove washer bottle filler neck.
(4) Remove Transmission Control Module (TCM)

reposition out of the way (Fig. 27).

(5) Remove PCM
(6) Disconnect PCM 2 40-way connector.

INSTALLATION

(1) Attach 2 40-way connector to PCM.
(2) Install PCM. Tighten bolt to 4 N·m (35 in. lbs.)

torque.

(3) Install TCM.
(4) Install washer bottle filler neck.

Fig. 23 Chipped Electrode Insulator

Fig. 24 Preignition Damage

Fig. 25 Spark Plug Overheating

8D - 10

IGNITION SYSTEM

300M

DIAGNOSIS AND TESTING (Continued)

(5) Reposition wiring harness.
(6) Install speed control servo and bracket and

tighten fasteners

(7) Connect negative battery cable and reprogram

radio and clock.

(8) Using DRB scan tool, program mileage and

vehicle identification number (VIN) into PCM. Refer
to the DRB scan tool and the appropriate Powertrain
Diagnostic Manual.

SPARK PLUG

Always remove the spark plug boot by grasping at

the spark plug boot, turning the boot 1/2 turn and
pulling straight back in a steady motion.

REMOVAL

(1) Prior to removing the spark plug, spray com-

pressed air around the coil area and spark plug.

(2) Remove electrical connector from ignition coil.
On 3.2/3.5L engines, it is necessary to loosen the

screws by alternating back and forth. Do not lose the
spacers under the coil when loosening the screws.

(3) Remove 2 fasteners from ignition coil.
(4) Remove ignition coil.
(5) Remove rubber boot from spark plug.
(6) Remove the spark plug using a quality socket

with a rubber or foam insert.

(7) Inspect the spark plug condition. Refer to

Spark Plug Condition in this section.

INSTALLATION

(1) To avoid cross threading, start the spark plug

into the cylinder head by hand.

(2) 3.2/3.5L engines tighten spark plugs to 28 N·m

(20 ft. lbs.) torque, 2.7L engine tighten spark plugs to
17.6 N·m (13 ft. lbs.).

(3) Install rubber boot onto ignition coil.
(4) Install ignition coil and boot onto spark plug.
(5) Install coil screws an tighten. 2.7L engine to

6.2 N·m (55 in. lbs.), 3.2/3.5L engines to 6.7 N·m (60
in. lbs.).

(6) Connect the electrical connector.

IGNITION COIL

REMOVAL

(1) Prior to removing the ignition coils, spray com-

pressed air around the coil area and spark plug.

(2) Remove electrical connector from ignition coil.
On 3.2/3.5L engines, it is necessary to loosen the

screws by alternating back and forth. Do not lose the
spacers under the coil when loosening the screws.

(3) Remove 2 fasteners from ignition coil.
(4) Remove ignition coil.

INSTALLATION

(1) Install ignition coil onto boot for spark plug.
(2) Install coil screws an tighten. 2.7L engine to

6.2 N·m (55 in. lbs.), 3.2/3.5L engines to 6.7 N·m (60
in. lbs.).

(3) Connect the electrical connector.

Fig. 26 PCM Location

Fig. 27 TCM Location

300M

IGNITION SYSTEM

8D - 11

REMOVAL AND INSTALLATION (Continued)