[header] How to find a vacuum leak [title] Consult the vacuum diagram of your engine. [step] In order to understand where your engine's vacuum hoses are and what areas might be leaking, you can look at a diagram that details how the vacuum system works. These diagrams can typically be found in repair manuals made for your specific make, model, and year of car. 
[substeps] Many repair manuals can be bought from online retailers or can be found online in digital form. [title] Start the car and listen for a hissing sound.