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 accelerator pedal position (APP) sensor. A faulty APP sensor or pedal linkage can cause a high APP sensor voltage. Under these conditions the PCM may not provide the correct fuel or throttle position for easy engine starting. Monitor the
APP sensor 1 voltage with the scan tool. The indicated voltage should be approximately 0.5-1.1 volts with the throttle closed. |
| • | 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 9-14 percent with the 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
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| • | 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. |
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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. |
| • | If the vehicle takes longer to start in cold weather, test for no a Crank Signal at the powertrain control module (PCM) connector C1 terminal 17. 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). |
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Ignition System Checks
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| • | Inspect the spark plugs for correct operation and good ignition system performance. Refer to
Spark Plug Inspection
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| • | Check for bare or shorted ignition system wiring. |
| • | Check for loose ignition coil connections. |
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Additional Checks
| Check the Service Bulletins for any updates.
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