1. Crankshaft Position Sensor (CKP Sensor): This is a prime suspect. A failing CKP sensor can cause erratic starting, especially in cold weather. The sensor provides the engine computer with information about the crankshaft's position, allowing for precise fuel injection and ignition timing. A faulty sensor might provide inaccurate signals, leading to a lean mixture or improper ignition timing, making starting difficult. Full throttle enriches the mixture, potentially overcoming the sensor's deficiency enough to allow starting.
2. Throttle Position Sensor (TPS): A faulty TPS can cause similar problems. The computer relies on the TPS to determine throttle position and adjust fuel delivery accordingly. A malfunctioning TPS could be providing incorrect readings, making cold starts difficult. The need to hold the throttle open could be compensating for the incorrect signal.
3. Fuel Pump/Fuel Pressure: Weak fuel pump pressure, especially when cold, can make starting difficult. The full throttle compensation might be providing enough fuel to overcome this. Have fuel pressure tested.
4. Mass Airflow Sensor (MAF Sensor): A dirty or faulty MAF sensor can lead to a lean air-fuel mixture, making cold starts difficult. Full throttle again might overcome this.
5. Low Oil Pressure at Idle (Separate Issue): The low oil pressure below 1000 RPM is a serious concern. This could be due to several factors:
* Low oil level: Check your oil level immediately. Low oil will cause low oil pressure.
* Worn bearings: This is a significant problem. Worn crankshaft or camshaft bearings will allow oil to leak past the clearances, resulting in low pressure. This requires a major engine repair.
* Oil pump: A failing oil pump will also result in low oil pressure.
* Oil viscosity: Very thick oil (wrong weight for the temperature) can cause poor oil flow at low engine speeds.
Troubleshooting Steps:
1. Check the oil level immediately. Add oil if needed, but *do not* overfill.
2. Check the battery voltage and cables: Weak battery can exacerbate starting problems.
3. Have the fuel pressure tested: This is essential to rule out fuel delivery problems.
4. Have the oil pressure tested: This will confirm the oil pressure issue and its severity. A mechanical gauge connected directly to the engine block is preferred over the dash gauge.
5. Scan the engine's computer for diagnostic trouble codes (DTCs): This can point directly to the faulty sensor. You can do this with an OBD-II scanner (available at most auto parts stores).
6. Inspect the CKP and TPS sensors: Look for obvious damage or corrosion. Cleaning the sensors might help (if it's only dirt or debris). However, replacement is often necessary.
7. Clean the MAF sensor (carefully): Use MAF sensor cleaner, following the instructions carefully.
Important: The low oil pressure is the most urgent issue. Driving with low oil pressure will severely damage your engine. Have this addressed immediately. If the problem is worn bearings, it is an expensive engine rebuild.
This information is for guidance only. Consult a qualified mechanic for proper diagnosis and repair. Ignoring the low oil pressure could lead to catastrophic engine failure.
