Quote:
Originally Posted by auc-05l
had this issue. its the hose connecting the pcv valve to the manifold. probably split. bastard of a job to fix as the inlet manifold has to come off. hows your fuel economy? |
Definitely this. Happened on my 05 Mondeo (apparently very similar to the Focus). And yes, it is a nasty job. You might be able to see the split if you know where you're looking and might even be able to feel it if you have small enough arms.
We found on the Mondeo that it only happened on start up when the engine wasn't warm. Leave the car for a few hours and it would do it again.
You could see what was happening once you get the hose out, on start up you get a massive vacuum leak until the hose sucks the cut part inside itself, basically making itself G-shaped. Once the wound is closed, you're back to metered air and it's like it never happened.
Here's a picture of my hose, with the new hose installed onto the manifold on the right:
https://drive.google.com/file/d/1iaR...ew?usp=sharing
Might also pay to get yourself a new
PCV valve while you're in there too.