Hard Start: Sensor/System
WARNING: This page is about a different car, the 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, 2003 Chevrolet Monte Carlo, and 2003 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
- Check for an Engine Coolant Temperature (ECT) sensor that has shifted in value. Connect a scan tool and compare ECT with Intake Air Temperature (IAT) on a cold engine. The ECT and IAT should be within 5°F of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. Go to TEMPERATURE VS. RESISTANCE table. If the ECT sensor resistance is not within the specification, go to DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT - LOW VOLTAGE or DTC P0113: INTAKE AIR TEMPERATURE SENSOR CIRCUIT - HIGH VOLTAGE under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
- Monitor the 24X crank sensor and CMP sensor signal present parameters on a scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor A and CMP sensor circuits for intermittents.
- Monitor the 3X crank sensor parameter on the scan tool. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a DTC immediately, but are capable of causing driveability complaints.
- Inspect the Mass Airflow (MAF) sensor for proper installation and conditions. A MAF sensor with a damaged honeycomb may cause a hard start. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the MAF sensor and the throttle body.
- Using a scan tool, test the Idle Air Control (IAC) operation. Command the engine RPM to 1500 RPM and back to the starting RPM. If the engine RPM does not change when commanded refer to DTC P0506: IDLE SPEED LOW and DTC P0507: IDLE SPEED HIGH to diagnose the IAC system.
- Inspect the Exhaust Gas Recirculation (EGR) system for proper sealing/connections and operation.
(1)
TEMPERATURE VS. RESISTANCE
| °F (°C) | Ohms | ||
|---|---|---|---|
| 302 (150) | 47 | ||
| 284 (140) | 60 | ||
| 266 (130) | 77 | ||
| 248 (120) | 100 | ||
| 230 (110) | 132 | ||
| 212 (100) | 177 | ||
| 194 (90) | 241 | ||
| 176 (80) | 332 | ||
| 158 (70) | 467 | ||
| 140 (60) | 667 | ||
| 122 (50) | 973 | ||
| 113 (45) | 1188 | ||
| 104 (40) | 1459 | ||
| 95 (35) | 1802 | ||
| 86 (30) | 2238 | ||
| 77 (25) | 2796 | ||
| 68 (20) | 3520 | ||
| 59 (15) | 4450 | ||
| 50 (10) | 5670 | ||
| 41 (5) | 7280 | ||
| 32 (0) | 9420 | ||
| 23 (-5) | 12,300 | ||
| 14 (-10) | 16,180 | ||
| 5 (-15) | 21,450 | ||
| -4 (-20) | 28,680 | ||
| -22 (-30) | 52,700 | ||
| -40 (-40) | 100,700 | ||
|
|||