| The Problem | Is Caused By | What To Do |
|---|---|---|
| Intake backfire | Improper ignition timing | Adjust timing |
| Defective EGR component | Repair as necessary | |
| Defective TAC vacuum motor or valve | Repair as necessary | |
| Exhaust backfire | Air leak into manifold vacuum | Check manifold vacuum and repair as necessary |
| Faulty air injection diverter valve | Test diverter valve and replace as necessary | |
| Exhaust leak | Locate and eliminate leak | |
| Ping or spark knock | Incorrect ignition timing | Adjust timing |
| Distributor advance malfunction | Inspect advance mechanism and repair as necessary (Distributor systems only) | |
| Excessive combustion chamber deposits | Remove with combustion chamber cleaner | |
| Air leak into manifold vacuum | Check manifold vacuum and repair as necessary | |
| Excessively high compression | Test compression and repair as necessary | |
| Fuel octane rating excessively low | Try alternate fuel source | |
| Sharp edges in combustion chamber | Grind smooth | |
| EGR valve not functioning properly | Test EGR system and replace as necessary | |
| Surging (at cruising to top speeds) | Low fuel pump pressure or volume | Replace fuel pump |
| Improper PCV valve air flow | Test PCV valve and replace as necessary | |
| Air leak into manifold vacuum | Check manifold vacuum and repair as necessary | |
| Incorrect spark advance | Test and replace as necessary | |
| Restricted fuel filter | Replace fuel filter | |
| Restricted air cleaner | Clean or replace air cleaner filter element | |
| EGR valve not functioning properly | Test EGR system and replace as necessary | |