* Crankshaft Position Sensor (CKP) or Camshaft Position Sensor (CMP): These sensors tell the ECU the engine's rotational position, crucial for proper ignition timing and fuel injection. A faulty sensor will prevent a consistent start. Try replacing or testing these sensors first. A failing sensor might give intermittent readings, leading to the one-or-two-kick behavior.
* Ignition Control Module (ICM): This module controls the ignition system. A failing ICM might provide spark intermittently, explaining the weak starting attempt. This is less likely if you've already confirmed spark, but a weak or intermittent spark could be the culprit.
* Airflow Sensor (MAF) or Throttle Position Sensor (TPS): While less likely to directly prevent *any* cranking, a severely faulty MAF or TPS could give the ECU incorrect information leading to poor fuel mixture or timing, resulting in a weak start attempt. Check these sensors for proper operation and clean them if necessary.
* Low Compression: While you say you have spark and fuel, low compression in one or more cylinders prevents the engine from starting properly. A compression test is essential to rule this out. Low compression could mean a blown head gasket, worn piston rings, or valve problems.
* Timing Belt: A jumped or broken timing belt would severely affect engine starting. Verify the timing belt's condition and ensure it's properly timed.
* ECU Problems: Less common, but a faulty ECU can cause a variety of starting issues. This is generally a last resort diagnosis.
Troubleshooting Steps:
1. Compression Test: This is the most important next step. Low compression indicates a major mechanical problem.
2. Check CKP and CMP Sensors: Test these sensors for proper voltage and signal output using a multimeter or a scan tool. Replacement is often the easiest solution if testing indicates a faulty sensor.
3. Inspect Timing Belt: Visually inspect the timing belt for damage or slippage.
4. Check for any error codes: Use a scan tool (OBD-II reader) to check for any diagnostic trouble codes (DTCs) stored in the ECU. This could point to a specific problem area.
The "one or two kicks" suggests a problem with ignition timing or a lack of sufficient fuel/air mixture to sustain combustion. The fact that you've confirmed fuel at the rail and spark narrows down the possibilities considerably, making the CKP/CMP sensors, the ICM, and a compression test the next critical steps. Do not assume that "spark" is consistent and strong. A weak spark can still appear present on a basic test but be insufficient for reliable ignition.
