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Rough Idle after running the engine for an hour?

Tiny
JUAN GERA
  • MEMBER
  • 2015 MITSUBISHI OUTLANDER SPORT
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 73,000 MILES
Hello, mechanics and fellow car enthusiasts.

My car starts rough idle after running for an hour; it gets worse if I turn on the AC.

The things I did.
New sparkplugs
New fuel pump
Cleaned and test fuel injectors - fuel injectors are okay
Cleaned throttle body
Ignition coil test - coils are okay
New PCV Valve

By the way, there's no check engine light. I would appreciate it so much if someone could help me.
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Wednesday, December 11th, 2024 AT 9:16 PM

7 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,313 POSTS
There are a few things that can make it act this way, vacuum leaks, weak MAF sensor, low compression in one cylinder, bad timing chains, please go over this guide to see what the popular problem are, I would try a new MAF sensor because I have seen these sensors cause this problem.

https://www.2carpros.com/articles/repairing-engine-rough-idle-issues

Here is the location of the sensor if you want to swap it out. Also, can you tell me the fuel trims? Please go over this guide to read them:

https://youtu.be/u-4syLc-ifQ

Check out the images (below). Please let us know what happens.
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Thursday, December 12th, 2024 AT 1:05 PM
Tiny
JUAN GERA
  • MEMBER
  • 5 POSTS
Thank you for your response, Ken. This is the data stream when the engine just starts up.
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Thursday, December 12th, 2024 AT 5:32 PM
Tiny
JUAN GERA
  • MEMBER
  • 5 POSTS
And in the last 10 seconds of this video. That's where the engine acting up rough.
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Thursday, December 12th, 2024 AT 5:41 PM
Tiny
JUAN GERA
  • MEMBER
  • 5 POSTS
Hopefully that data helps. Thank you so much Ken.
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Thursday, December 12th, 2024 AT 5:42 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,313 POSTS
So what I see is the IAT sensor says it is over 100 degrees, is it this hot where you live? If not, I would replace the IAT sensor first, thanks for the videos they helped. Also, I see a bunch of erratic readings fuel trims, but the IAT might cause this so let's replace that first and clear any codes once competed, here is the location of the sensor which is part of the MAF sensor just to let you know.
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Friday, December 13th, 2024 AT 12:32 PM
Tiny
JUAN GERA
  • MEMBER
  • 5 POSTS
We are in a tropical area. But it was impossible to reach that temperature, especially since the engine had just started, and I recorded the video early in the morning. Thank you so much for the help, Ken. I highly appreciate it.
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Friday, December 13th, 2024 AT 3:11 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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You are welcome, lets swap out that sensor and clear the codes to see what happens.
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Saturday, December 14th, 2024 AT 10:15 AM

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