How do you adjust 2001 Chevy S-10 timing?

You cannot adjust the timing on a 2001 Chevy S-10 (or most modern vehicles) in the same way you could on older cars with distributor-based ignition systems. The 2001 S-10 uses an electronically controlled ignition system. The timing is controlled by the Engine Control Module (ECM) and is continuously adjusted based on various engine sensors. There's no distributor to rotate or timing marks to adjust.

Trying to manually adjust the timing on this engine will likely damage the engine and/or the ECM.

If you're experiencing timing-related issues (rough running, poor performance, etc.), you need to address the underlying problem, which could include:

* Faulty Crankshaft Position Sensor (CKP): This sensor tells the ECM where the crankshaft is in its rotation. A bad CKP sensor will lead to erratic timing.

* Faulty Cam Position Sensor (CMP): Similar to the CKP sensor, but for the camshaft.

* ECM Problems: The ECM itself could be malfunctioning.

* Vacuum Leaks: Vacuum leaks can affect engine performance and potentially lead to perceived timing issues.

* Ignition System Problems: Issues with ignition coils, spark plugs, or wires can also mimic timing problems.

Instead of trying to adjust the timing, you should:

1. Have the vehicle diagnosed by a qualified mechanic: They have the tools (scanners) to read diagnostic trouble codes (DTCs) from the ECM, which can pinpoint the source of the problem.

2. Inspect the obvious: Check for any obvious vacuum leaks, damaged wires, or loose connections.

Trying to "adjust" the timing on a modern vehicle's ECM-controlled system without specialized tools and knowledge is extremely risky and will likely cause more harm than good. Always take your vehicle to a qualified mechanic if you suspect a timing-related issue.