They should all be around 15-17 inches of vacuum at idle. Tony On Sat, Jul 24, 2010 at 3:52 PM, Radek <radek at istar.ca> wrote: > Anybody know what should be the value of vacum at idle on a 5-cyl Audi engine? Is it similar for all normally aspirated engines? > Thanks. > Radek > 88 90Q > 91 V8Q 5-sp.