What you're likely experiencing is a problem with one of these components, which might be mistaken for an ignition modulator issue based on symptoms:
* Ignition Control Module (ICM): This is a common failure point in many GM vehicles of that era. It's a part of the ignition system and often sits near the distributor or coil. A faulty ICM can cause misfires, starting problems, or complete engine failure.
* Crankshaft Position Sensor (CKP): This sensor tells the ECM the position of the crankshaft, crucial for precise ignition timing. A bad CKP will often result in no start or very erratic running.
* Camshaft Position Sensor (CMP): Similar to the CKP, but for the camshaft. This sensor is important for fuel injection timing, among other things. A failure here can result in rough running or no start.
* ECM (Engine Control Module): This is the "brain" of the fuel injection system and the ignition system. Problems here can manifest in various ways, making diagnosis difficult.
* Ignition Coil: Provides the high voltage needed to fire the spark plugs. A bad coil will cause misfires.
* Distributor (if equipped): Some 2.8L engines of that year may still use a distributor. Problems here could include wear on the internal components, causing ignition issues. However, given the multi-port fuel injection, a distributor is less likely.
Troubleshooting Steps:
1. Diagnose the problem: Before replacing parts, determine *what* is malfunctioning. Is the engine cranking but not starting? Is it misfiring? Is it running rough? The symptoms will guide you to the most likely culprit.
2. Check for codes: Your car likely has a diagnostic port (ALDL - Assembly Line Data Link). You'll need a code reader or a scan tool to check for any diagnostic trouble codes (DTCs) stored in the ECM. These codes can pinpoint the problem area.
3. Visual Inspection: Inspect the wires, connectors, and components mentioned above for signs of damage, corrosion, or loose connections.
4. Professional Diagnosis: If you're not comfortable with automotive diagnostics, it's best to take your car to a qualified mechanic. They have the tools and expertise to diagnose the problem accurately and efficiently. Improperly replacing parts can be costly and may not solve the issue.
In short: There's no "ignition modulator" to replace. You need to find the actual failing component through diagnostics. Replacing parts randomly is inefficient and expensive.
