Can you adjust the timing on a 1998 Chevy Silverado?

You can't adjust the timing on a 1998 Chevy Silverado (or most modern vehicles) in the same way you could on older cars with distributors. The 1998 Silverado's ignition timing is controlled by the engine control module (ECM), also known as the PCM (powertrain control module). It's a computer that constantly adjusts the timing based on various sensor inputs. There's no external timing mechanism to adjust manually.

Any attempt to "adjust" the timing would likely involve:

* Replacing the ECM: If the ECM is malfunctioning and causing poor timing, it would need to be replaced. This is not a DIY task for most people; specialized tools and knowledge are required.

* Addressing sensor issues: Faulty sensors (like the crankshaft position sensor, camshaft position sensor, etc.) can affect the ECM's ability to accurately control timing. These sensors would need to be diagnosed and replaced if faulty.

* Repairs to the ignition system: Problems with the ignition coil, spark plug wires, or spark plugs can affect ignition timing indirectly, so those should be checked.

In short, if you're experiencing timing-related issues (poor performance, misfires, etc.), you need to have a professional mechanic diagnose the problem. Trying to adjust the timing yourself on this type of vehicle is extremely unlikely to work and could potentially damage the engine or other components.