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Old 20-05-2021, 03:21 PM   #6
auc-05l
Starter Motor
 
Join Date: Feb 2021
Posts: 11
Default Re: RPM shooting up at start up

Quote:
Originally Posted by Metdevil View Post
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.
yep thats what mine looked like. i got my hose from overseas as ford wanted $120! pcv valve was a much more reasonable $24 from ford.
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