Checks
| Action
|
DEFINITION: Engine
cranks OK, but does not start for a long time. Does eventually run, or may
start but immediately stalls.
|
Preliminary
|
| • | Verify that the powertrain control module (PCM) grounds are clean,
tight, and in the correct locations. |
|
Sensor
or System
|
| • | Inspect the engine coolant temperature (ECT) sensor for a shifted
value. Connect a scan tool and compare the ECT with the intake air temperature
(IAT) on a cold engine. The ECT and IAT should be within ± 3°C
(5°F) of each other. Inspect the resistance of the ECT sensor if
the temperature is out of range with the IAT sensor. Refer to
Temperature Versus Resistance
for resistance
specifications. Replace the ECT sensor if the resistance is not within the
specification. If the sensor is within the specification, repair the
high resistance in the ECT signal circuit . |
| • | Inspect the mass airflow (MAF) sensor installation. |
| • | Using a scan tool, monitor the throttle position (TP) sensor voltage.
The TP sensor voltage should be less than 0.9 volt at rest. If the
TP sensor voltage is more than 0.9 volt, inspect the throttle
body and the accelerator cables for binding. |
| • | Inspect the exhaust gas recirculation (EGR) system for correct
operation. |
|
Fuel
System
|
| • | Inspect the fuel pump relay operation. The pump should turn on
for 2 seconds when the ignition is turned ON. |
| • | A faulty in-tank fuel pump check valve will allow the fuel in
the lines to drain back to the tank after the engine is stopped. To inspect
for this condition, refer to
Fuel System Diagnosis
. |
| • | Inspect the injector fuses for being open. Replace the fuses if
necessary and inspect the injector circuits for an intermittent short to ground. |
| • | Inspect for a low fuel pressure. |
| • | Inspect for a restricted fuel filter. |
|
Ignition
System
| Remove
the spark plugs. Inspect for the following:
If the spark plugs are gas or oil fouled, determine the cause of the
fouling before replacing the spark plugs.
| • | Inspect the plugs and the coils for signs of arcing or carbon
tracking. |
| • | Inspect for loose ignition control module (ICM) grounds. |
| • | Inspect the spark plugs for the correct heat range. |
|
Engine
Mechanical
| Inspect for the following conditions:
| • | Any excessive oil in the combustion chamber may indicate leaking
valve seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical-3.5L. |
| • | Any excessive carbon buildup in the combustion chambers. Clean
the chambers using Top Engine cleaner. Follow the instructions on the container. |
| • | Any incorrect basic engine parts. Inspect the following: |
Refer to
Symptoms - Engine Mechanical
in
Engine Mechanical-3.5L.
|
Additional Checks
| Using a scan tool, inspect the idle air control
(IAC) operation and the Typical Scan Data values.
|
