Rough idle when stopped

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

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?

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.

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.