High Probability Issues:
* Cranking but not starting: If the engine cranks (turns over) but won't fire, the problem likely lies in:
* Fuel Delivery:
* Fuel pump: Check if the fuel pump is working. You might hear it prime when you turn the key to the "on" position (before cranking). A bad fuel pump relay is also possible.
* Fuel filter: A clogged fuel filter restricts fuel flow.
* Fuel pressure: You'll need a fuel pressure gauge to check if the fuel pressure is adequate.
* Injectors: While less likely after a recent coil/module replacement, faulty injectors can prevent fuel from entering the cylinders. A simple check with a noid light can help determine if they are getting a signal.
* Spark (despite new parts):
* Wiring: Faulty wiring between the ignition module, coil packs, and distributor (if equipped) can still prevent spark. Check for broken wires, corrosion, or poor connections. A visual inspection is crucial.
* Distributor Cap and Rotor (if applicable): Even with a new module, a bad distributor cap or rotor can interrupt spark. Inspect for cracks, corrosion, or carbon tracking. Your 1998 S10 *might* have a distributor; some years of that model used a distributorless ignition system (DIS).
* Crankshaft Position Sensor (CKP): The computer needs a signal from the CKP to know when to fire the coils. A bad sensor will prevent starting.
* Cam Position Sensor (CMP): Similar to the CKP, a bad CMP will also prevent a proper firing order.
* No Cranking: If the engine doesn't even crank, the issue is likely outside the ignition system:
* Battery: A dead or weak battery can prevent the starter from engaging.
* Starter: A faulty starter motor or its related wiring could be at fault.
* Neutral Safety Switch: This prevents starting unless the transmission is in Park or Neutral.
* Ignition Switch: A problem with the ignition switch itself could prevent power from reaching the starter.
Lower Probability Issues:
* Computer (PCM): Though less likely given the recent ignition component replacements, a faulty PCM could be sending incorrect signals or not powering the ignition system correctly. This is usually diagnosed via a scan tool.
* Security System: Some vehicles have immobilizers that prevent starting if they don't recognize the key.
Troubleshooting Steps:
1. Check the basics: Battery voltage, fuel in the tank, and any obvious broken wires.
2. Listen for the fuel pump: Turn the key to the "on" position and listen for the whirring sound of the fuel pump.
3. Inspect wiring: Carefully examine all wiring related to the ignition system for any damage or corrosion.
4. Check for spark: Use a spark tester or even a gap-bridged spark plug wire to see if spark is reaching the plugs.
5. Use a multimeter: Check for power and ground at the coil packs and ignition module.
6. If you have a distributor, inspect the cap and rotor.
7. Consider a scan tool: A scan tool can read diagnostic trouble codes (DTCs) from the PCM, which can help pinpoint the problem.
If you're not comfortable working on your vehicle's electrical system, it's best to take it to a qualified mechanic. Improperly diagnosing and repairing electrical issues can lead to further damage.
