Here's the procedure:
1. Safety First: Disconnect the negative (-) battery cable before starting any work on the ignition system.
2. Gather Tools: You'll need a timing light, a socket wrench set, a shop manual (highly recommended!), and possibly a helper. A dial-back timing light is ideal, offering a more precise reading.
3. Locate Timing Mark: Consult your shop manual to locate the timing marks on the harmonic balancer (vibration damper) and the timing pointer on the engine block. The marks will typically be a notch or arrow on the balancer and a pointer on the engine.
4. Access the Timing Mark: You might need to remove some components (e.g., the air cleaner housing, etc.) to get a clear view of the timing mark on the harmonic balancer.
5. Find TDC on #1 Cylinder: This is critical. The shop manual will specify how to do this accurately. Usually, it involves removing a spark plug, inserting a long screwdriver or feeler gauge through the spark plug hole, and rotating the engine by hand until you feel the piston reach the top of its stroke (TDC). Then, carefully double-check to confirm that #1 cylinder is indeed at the compression stroke (both valves closed). Incorrect TDC will give completely inaccurate timing readings.
6. Connect the Timing Light: Clip the timing light's inductive clamp around the #1 spark plug wire. Connect the timing light's power leads to the battery.
7. Start the Engine: Have a helper crank the engine, making sure it's running smoothly at idle (the shop manual should specify the correct idle RPM).
8. Read the Timing: Aim the timing light at the timing marks on the harmonic balancer. The timing mark should align with the timing pointer. Your shop manual will specify the correct timing value (degrees BTDC - Before Top Dead Center) for your '85 Fiero V6 at idle.
9. Interpret the Results: If the timing mark is significantly off from the specified value, there might be issues with the ignition control module (ICM), crankshaft position sensor (CKP), camshaft position sensor (CMP), or other related components. The shop manual should provide troubleshooting steps to identify these potential failures.
Important Considerations for the '85 Fiero V6:
* Electronic Ignition: Remember, you're *not* adjusting the timing; you're only checking it. There's no distributor to adjust. Any adjustment needs to be done through the ECM (Engine Control Module) reprogramming, which is usually beyond DIY scope.
* Computer Control: The timing is controlled by the onboard computer. The system accounts for various parameters like engine temperature and load.
* Shop Manual: A factory service manual for your specific year and model is invaluable. It will provide detailed diagrams and specifications crucial for accurate timing verification.
If the timing is significantly off, further diagnosis is needed. It's best to consult a qualified mechanic familiar with these electronic ignition systems to avoid damaging your engine. Attempting advanced troubleshooting without proper understanding can lead to more serious problems.
