Checks
| Action
|
DEFINITION: Engine cranks OK, but does not start for a
long time. Does eventually run, or may start but immediately stalls.
|
Preliminary
|
| • | Refer to
Symptoms
, Important
Preliminary Checks Before Starting. |
| • | Verify that the PCM grounds are clean, tight, and in the correct
locations. |
|
Sensor or System
|
| • | Check 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. Check 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 . |
| • | Check the mass air flow (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. |
| • | Check the EGR system for correct operation. |
|
Fuel System
|
| • | Check 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 check
for this condition, refer to
Fuel System Pressure Test
. |
| • | Check the injector fuses for being open. Replace the fuses if
necessary and inspect the injector circuits for an intermittent short to ground. |
| • | Check for a low fuel pressure. |
| • | Check for a restricted fuel filter. |
|
Ignition System
| Remove the spark plugs and check for the following:
If the spark plugs are gas or oil fouled, the cause of the fouling must
be determined before replacing the spark plugs.
| • | Check the plugs and the coils for signs of arcing or carbon tracking. |
| • | Check for loose ignition control module grounds. |
| • | Check the spark plugs for the correct heat range. |
|
Engine Mechanical
| Check for the following conditions:
| • | Any excessive oil in the combustion chamber may indicate leaking
valve seals. Refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
| • | 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
Base Engine Misfire Diagnosis
in Engine Mechanical.
|
Additional Checks
| Using a scan tool, check the idle
air control (IAC) operation and the Typical Scan Data values.
|
