Ignition System:
* Ignition switch: This is a common culprit in older cars. A failing ignition switch might not consistently send power to the starter.
* Ignition coil: A weak or failing ignition coil won't provide sufficient spark to ignite the fuel-air mixture reliably.
* Spark plugs and wires: Worn, corroded, or cracked spark plugs and wires can lead to misfires and starting difficulties. Check for gaps and corrosion.
* Distributor cap and rotor (if applicable): If your Metro has a distributor, these parts can become worn, causing poor spark distribution. Look for cracks, corrosion, or worn contact points.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position, crucial for precise ignition timing. A faulty CKP can lead to no-start or intermittent starting issues.
* Cam Position Sensor (CMP): Similar to the CKP, a failing CMP can disrupt the timing of fuel injection and ignition.
Starting System:
* Starter motor: While the starter *might* crank weakly, intermittent problems suggest it might be failing. It might be drawing too much current, even if the battery tests fine.
* Starter solenoid: This is the electromagnet that engages the starter motor. A faulty solenoid will prevent the starter from cranking. A clicking sound when you turn the key is often a sign of a bad solenoid.
* Battery cables and connections: Even if the battery tests good, corroded or loose connections at the battery terminals, starter, and alternator can impede current flow, causing intermittent starting. Clean and tighten all connections.
Fuel System:
* Fuel pump: A failing fuel pump might not deliver fuel consistently, leading to intermittent starting. You might hear a humming sound from the fuel pump when you turn the key if it’s failing.
* Fuel filter: A clogged fuel filter restricts fuel flow, potentially causing starting problems, especially when the engine is cold.
* Fuel injectors: Clogged or malfunctioning fuel injectors can prevent sufficient fuel from reaching the combustion chamber.
Other Possibilities:
* Neutral safety switch: This switch prevents the car from starting unless it's in park or neutral. A faulty switch can cause intermittent starting problems.
* Computer/ECM issues: While less common, a problem with the car's Engine Control Module (ECM) could cause intermittent starting, especially if there are other related symptoms.
* Security system (if equipped): If your Metro has a factory or aftermarket alarm or immobilizer, a malfunction could prevent starting.
Troubleshooting Steps:
1. Start with the easy checks: Clean battery terminals, inspect all wiring for damage, and check all fuses.
2. Listen carefully: Does the engine crank but not start (fuel or ignition problem)? Do you hear a click (solenoid)? Does the starter crank weakly (starter motor or battery connection)?
3. Check for diagnostic trouble codes (DTCs): If the Check Engine light is on, read the codes with an OBD-II scanner. This can pinpoint specific issues. Keep in mind that older cars like the Metro may not have a fully compliant OBD-II system.
4. Visual inspection: Check for obvious signs of wear or damage in all components mentioned above.
Because you've ruled out battery and alternator, it's time to systematically investigate the ignition, starting, and fuel systems. If you're not comfortable working on your car yourself, it's best to take it to a mechanic for diagnosis and repair. They have the tools and experience to pinpoint the problem more efficiently.
