Hard Start
Checks
| Action
|
DEFINITION: The engine cranks OK, but does not start for a long time. The engine
does eventually run, or maystart but immediately dies.
|
Preliminary Checks
|
| • | Check that the driver is using the correct starting procedure. |
|
Sensor Checks
|
| • | 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 RPMwhile cranking.
If erratic values, such as sudden spikes in theenginespeed,are displayed,
the engine reference signal is notstable enoughforthe engine to start
and run properly. |
|
Fuel System Checks
|
| • | 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
|
| • | 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. |
|
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
. |
| • | Check the Service Bulletins for any updates. |
|
