Inspections
| Action
|
DEFINITION: Steady pulsation or jerking that follows engine speed, usually more
pronounced as engine load increases.
|
Preliminary
|
|
Fuel System
|
| • | Test the fuel injectors using the following tests: |
| • | Inspect items which can cause an engine to run rich (long term fuel trim
significantly in the negative range). Refer to Diagnostic Aids for
DTC P0172
. |
| • | Inspect items that can cause an engine to run lean (long term fuel trim
significantly in the positive range). Refer to Diagnostic Aids for
DTC P0171
. |
| • | Inspect for fuel in the fuel pressure regulator vacuum hose. |
|
Sensor/System
|
| • | Inspect for conditions which cause an incorrect idle speed. |
| - | Throttle body tampering, excessive deposits, or damage |
| - | Restricted air intake system. |
| • | Test the throttle position (TP) sensor and related circuit wiring. Refer
to
DTC P0123
. |
| • | Test the positive crankcase ventilation (PCV) valve for proper operation. |
| • | Test the transaxle range switch input with the vehicle in drive and the
gear selector in drive or overdrive. |
| • | Inspect the following for damage: |
|
Ignition System
|
| • | Test for proper ignition voltage output using the following steps: |
| 1. | Clip the J 26792
Spark
Tester to engine ground. |
| 2. | Connect one end of a spark plug wire to the J 26792
. Connect the other end of the spark plug wire to the coil being
tested. |
| 3. | Connect another spark plug wire between the remaining tower of the coil
being tested and ground. |
| 4. | Crank the engine while observing the J 26792
. A spark should be observed. |
| 5. | Repeat the above steps for each coil. |
| • | If spark is not present at the coils, inspect for the following conditions: |
| - | Coils--Cracks, carbon tracking/arcing, or a secondary resistance
value outside the specified range. |
Coil Resistance
5000-8000 ohms (5K-8K ohms)
| | Important: Spraying the secondary ignition wires with
a light mist of water may help locate an intermittent condition. Ignition components
will arc to ground when a secondary component is faulty.
|
| - | Spark plug wires--Signs of arcing/cross firing, cracks, carbon tracking,
plug boot damage, pinched, improper routing, or a resistance value outside the specified
range. |
Spark Plug Wire Resistance
9840 ohms per meter (3000 ohms
per foot)
Spark Plug Wire Resistance Police
1,968 ohms per
meter (600 ohms per foot)
| - | Ignition system wiring--Loose ignition module feed or ground connection,
or damaged system wiring |
| • | Remove spark plugs and inspect for the following: |
| - | Burned or damaged electrodes |
| - | Improper heat range or reach |
| • | If spark plugs are gas or oil fouled, the cause of the fouling must be
determined before replacing the spark plugs. Refer to
Spark Plug Inspection
. |
| • | Test for the following intermittent ignition system conditions: |
| - | Intermittent CKP 18X signal |
| - | Intermittent ignition feed circuit or sensor ground circuit to the crankshaft
position sensor or the camshaft position sensor |
| - | Intermittent 3X reference signal |
| - | Intermittent camshaft position signal |
|
Engine Mechanical
|
| • | Test and inspect engine mechanical for the following: |
| - | Sticking or leaking valves |
| - | Excess oil in combustion chamber--Inspect for leaking valve seals. |
| • | Inspect for incorrect basic engine parts, such as the following basic
components: |
Refer to
Symptoms - Engine Mechanical
in Engine Mechanical - 3.8L.
|
Additional Inspections
|
| • | Test exhaust system for possible restrictions. Inspect for the following: |
| - | Inspect exhaust system for damaged or collapsed pipes. |
| - | Inspect mufflers for heat distress or possible internal failure. |
| - | For possible plugged 3-way catalytic converter--Refer to
Restricted Exhaust
in Engine Exhaust. |
| • | Inspect for intake and exhaust manifold passages for casting flash. |
| • | Inspect for faulty motor mounts. |
|
