Rough idle when stopped

Tiny
ALEX19899
  • MEMBER
  • 2013 NISSAN SENTRA
  • 1.8L
  • 4 CYL
  • 2WD
  • 80,000 MILES
This car has low idle around 600 rpm and car will shake at idle. Took it to dealership and they had to perform a relearn procedure for the idle since I recently replace battery. So they said it was good to go and on the way home my idle went back to 600 rpm. They set the idle to 712 apparently. But I'm not sure what else to do about this idle problem. Once I am driving, it idles normal it only has a rough idle at stop lights.
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Thursday, April 25th, 2019 AT 5:59 PM

7 Replies

Tiny
KASEKENNY
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Hi Alex,

It looks like your idle should be at 700 RPM with no load. This means park or N.

Also, it looks like all the dealer did is run the relearn procedure which you can do as well if you like. I attached a video that explains how to do it.

If your issue presents itself while in gear, this would be considered under load. This is normal to have the idle drop while under load but if it is shaking the vehicle and it didn't do this before, I would question if something else is wrong.

There could be an issue with an engine mount or something along those lines but if the dealer has a way to raise the idle while in gear, I would request they do this. Based on the steps of this relearn procedure, they did not actually set the idle. The vehicle learns the pedal position and throttle plate position and then the computer sets the idle. This is not like the old days where they can move the distributor or idle adjustment screw on a carburetor and adjust it. This is set electronically.

The question you need to ask the dealer that did this is, can you set or raise the idle while in gear? I don't not see a procedure for this so my guess will be no.

Last thing I would suspect is that the idle air control actuator is the issue. Either dirty or faulty. Normally, these are called an IAC but in your vehicle it appears this is called an Intake Manifold Runner Control Valve Motor. If this is dirty then when the ECM is commanding the position, it is actually not open enough because it is dirty and it restricts air flow. This is something you want to them to clean with an induction cleaning procedure just to ensure its not the issue.

https://youtu.be/7RC5ofxBVBs

Let me know what you find and we can go from there. Thanks
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Friday, April 26th, 2019 AT 2:57 PM
Tiny
ALEX19899
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Hello I cleaned the Manifold Runner Control Valve Motor and I performed the idle relearn successfully but it still goes back to the low idle.
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Tuesday, April 30th, 2019 AT 2:29 PM
Tiny
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Hi Alex,

I just want to be sure we are talking about the same thing. When you put the vehicle in gear and hold the brake the idle drops to 600 RPM and you feel the engine vibrating. When you put it in P or N the RPM come up to 712 and it runs very smooth?

If this is the case, I don't see any way to raise the RPM when in gear. This is all electronically controlled by the PCM. If the MRCV is clean and you relearned the throttle plate with this being clean then to my knowledge that is all that can be done. It is not like the older vehicles where you can set timing to your liking. When you relearn that throttle control it is basically re-calibrating it to the components to their current condition.

Did this issue just start or has it been doing it for a while? Did you just buy this vehicle or has this progressively gotten worse?
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Tuesday, April 30th, 2019 AT 3:56 PM
Tiny
ALEX19899
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This started to happen after I replaced the battery. I had the car for about 4 months
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Tuesday, April 30th, 2019 AT 4:41 PM
Tiny
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I doubt the battery is causing this but I would load test it just to be sure. After that checks out, I would call the dealer back and ask if they have a way to raise the RPM while in gear because I am not finding a way and I don't think there is. This idle may just be a characteristic of this vehicle.

Since you just bought it, make sure you check the motor/trans mounts.
They may be causing excessive vibration, because if the idle is normal maybe the vibration is caused by a bad mount.
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Tuesday, April 30th, 2019 AT 7:38 PM
Tiny
ALEX19899
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Are you able to tell me the locations for the mounts
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Tuesday, April 30th, 2019 AT 7:55 PM
Tiny
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I cannot find a picture that shows the location. However, I attached a picture of what they look like. There will be one on the side of the engine and transmission and then one underneath just being the oil pan.

Sorry to make you search for them but they are not hard to find once you know what they look like.
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Wednesday, May 1st, 2019 AT 3:58 PM

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