Got a couple codes from the diag. citing misfiring cylinders and leakage ( specificaly p0300 and p0171, p0500(?)) I have identified the general location of the leak in the rear of the engine bay, i was wondering if there were specific methods( like steam or smoke) to do detect a specific leak?

2003 a4Q 1.8t
Thanks!

 

look at the lines first......... spray them down with carb cleaner..... if the engine smooths out you've found it.

What you want to check for is for broken plastic check valves, there are a few in the back on the 1.8

 

and dont buy them from the stealership, they bilked me $46 for one check valve cuz i couldn't wait... on-line they are $12, and probably cost $1 TO make.

 

The pro's use a smoke machine to find leaks.

 

Pro don't use smoke machines to find vacuum leaks. You use smoke machines to find leaks in closed systems where lines are obstructed from view, like evap systems.

If you were to smoke a vacuum line the smoke would enter the intake manifold and trickle its way thru the whatever valves were open and out the exhaust

 

Yep, I was thinking evap and misspoke. Thanks for clarifying.