Here's what you *should* do:
1. Diagnose the problem: Before adjusting anything, determine *why* you think the timing is off. Symptoms like poor performance, rough idle, or pinging could indicate other issues (like a vacuum leak, faulty sensor, or bad fuel pressure) that are unrelated to the timing.
2. Check for Diagnostic Trouble Codes (DTCs): Your Caprice likely has a system for storing diagnostic trouble codes. Retrieve these codes (usually involves a process of shorting two wires under the dash – consult your owner's manual or a repair manual for specifics). These codes can pinpoint faulty sensors or components that might be affecting ignition timing.
3. Use a scan tool: A scan tool capable of reading engine data (like a code reader or a more advanced OBD1 diagnostic tool) is crucial. It'll allow you to monitor the actual ignition timing the computer is commanding. This eliminates guesswork. You'll be able to see if the computer is commanding timing that's within the expected range. A faulty sensor can cause the computer to command incorrect timing.
4. Professional Assistance: If you don't have the appropriate diagnostic tools and experience, take your Caprice to a qualified mechanic. They have the tools and knowledge to properly diagnose and correct timing issues on this type of fuel injection system. Improperly adjusting the distributor can cause serious engine damage.
Why you shouldn't just adjust the distributor:
The distributor on your 1989 Caprice is likely only adjustable to a very limited degree, and even then, it's primarily for initial base timing. The computer takes over and makes constant adjustments based on:
* Engine Load: Timing changes depending on how much power the engine is producing.
* Engine Speed: Timing changes based on RPM.
* Temperature: Timing changes based on engine temperature.
* Sensor Inputs: Various sensors (like the oxygen sensor, coolant temperature sensor, etc.) feed information to the computer which affects the timing.
Simply moving the distributor will only temporarily adjust the *base* timing, and the computer will likely counteract this adjustment with its own corrections, potentially leading to inconsistent timing and problems. A misadjusted base timing might cause erratic behavior, though. In short, you need to deal with the issue through diagnostics rather than direct manipulation of the distributor itself.
