RPM Hangs very hard?

Tiny
LUCAB_17
  • MEMBER
  • 2015 FORD FIESTA
  • 1.6L
  • 4 CYL
  • TURBO
  • 2WD
  • MANUAL
  • 120,000 MILES
The car listed above is a ST model with a 1.6 EcoBoost.

When the engine is hot after a rev in neutral the RPMs drop very slowly, they even stuck around 2,000 RPMs for some seconds (while the foot is completely off the gas pedal).
Tuesday, May 20th, 2025 AT 11:20 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,404 POSTS
Yep, this can happen when the turbo is leaking internally. I other words the exhaust gases are getting into the intake, or you have a vacuum leak, let follow these two guides to find the leak or the reason for the high idle.

https://www.youtube.com/watch?v=LRKWV4Are5c&t

and

https://www.2carpros.com/articles/engine-idles-too-high

Can I ask if you have a check engine light on? If so, we should run the codes. also did you notice if the engine is down on power? If so, this can be a sign the turbo is bad. If you can remove the intake or exhaust side of the turbo to check the main shaft endplay. Please go over these guides and get back to us.
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Tuesday, May 20th, 2025 AT 6:27 PM
Tiny
LUCAB_17
  • MEMBER
  • 2 POSTS
I had a check engine light: "P2187: System too lean at idle".

I don't really think the engine is down on power, but it could be, I don't really have the tools to check the turbo since it is not a really easy access.

I would love to check for vacuum leaks but I don't really have a smoke machine, I saw that it can be done with soapy water too but unfortunately I don't really know where the vacuum lines are and where should I spray the water? Can you guys help me out by indicating them for me?
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Wednesday, May 21st, 2025 AT 5:10 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 52,404 POSTS
Yep, it seems like you have a vacuum leak. I would use a smoke machine because it is difficult to find the leak on a turbo engine. I would inspect the turbo tubes and look for cracks or tears, the smoke machine is $70.00 on Amazon. Go back to the video and there will be a link. Let me know what happens.
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Thursday, May 22nd, 2025 AT 10:04 AM

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