Hard Start
Checks
| Action
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DEFINITION: The engine cranks OK, but does not start for a long time. The engine
does eventually run, or may start but immediately dies.
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Preliminary Checks
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| • | Check that the driver is using the correct starting procedure. |
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Sensor Checks
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| • | Check the engine coolant temperature (ECT) sensor using a scan tool to
compare the engine coolant temperature with the ambient air temperature on a cold
engine. If the coolant temperature reading is more than 5°C (9°F) more or
less than the ambient air temperature on a cold engine, check for a high resistance
in the coolant sensor circuit or in the sensor. Refer to
Temperature Versus Resistance. |
| • | Check the throttle position (TP) sensor. A sticking throttle shaft or
a binding throttle linkage will causes a high TP sensor voltage. Under these conditions
the PCM may not control the idle. Monitor the TP sensor angle with the scan tool.
The indicated angle should be approximately 9-11 percent with throttle
closed. |
| • | Inspect the mass air flow (MAF) sensor operation. Run the engine to normal
operating temperature. Turn OFF all accessories and observe the MAF sensor at idle
with a scan tool. If the MAF sensor reading is more than 3.5 g/s refer to
DTC P0101. |
| • | Check the crankshaft position (CKP) sensor engine reference signal with
a scan tool. Observe the Engine Speed parameter while cranking the engine. The scan
tool should indicate a steady 200-300 RPM while cranking. If erratic
values, such as sudden spikes in the engine speed are displayed, the engine reference
signal is not stable enough for the engine to start and run properly. |
|
Fuel System Checks
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| • | Check the fuel pump relay for correct operation. Observe the fuel pump
relay operation on a scan tool while cranking the engine. |
| • | Check for no Crank Signal at the powertrain control module (PCM) connector C2
terminal 9 if the vehicle takes longer to start in cold weather. Observe the
Starter Switch parameter on a scan tool while cranking the engine. The PCM provides
slightly more fuel for engine start up when receiving the crank input. |
| • | Check the fuel pump check valve. A faulty fuel pump check valve will allow
the fuel in the lines to drain back into the tank after stopping the engine. This
condition is especially troublesome on hot soak restarts. In order to check for this
condition perform the following steps: |
| 1. | Turn OFF the ignition. |
| 3. | Pressurize the fuel rail by turning the ignition key ON and OFF a few
times. |
| 4. | Turn the ignition key ON and observe the fuel pressure. The fuel pressure
has to remain more than 147 kPa (24 psi). |
|
Ignition System Checks
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| • | Inspect the spark plugs for correct operation and good ignition system
performance. Refer to
Spark Plug Inspection. |
| • | Check for bare or shorted ignition system wiring. |
| • | Check for loose ignition coil connections. |
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Additional Checks
|
| • | An idle air control (IAC) system that is malfunctioning can cause a hard
start condition. Hold the throttle open slightly while starting the engine. After
the vehicle is started the scan tool can be used to check the operation
of the IAC valve. Operate the IAC valve with the scan tool while checking for a smooth
increase and decrease in engine speed. If engine speed can be controlled, the IAC
system is functioning normally. If engine speed can not be controlled with the scan
tool refer to Diagnostic Aids in
DTC P0505. |
| • | If the engine stalls after starting inspect for a fault in the CMP Actuator
System or the Rocker Arm Oil Control System. A stuck ON control solenoid can cause
the engine to stall at idle speeds. Refer to
DTC P0012and
DTC P2647. |
| • | Check the Service Bulletins for any updates. |
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