Erratic RPMs

Tiny
PAPET
  • MEMBER
  • 2014 DODGE CARAVAN
  • 3.6L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 97,000 MILES
Since the P0302 had been fixed, the RPMs are a little higher than before. At startup, the RPMs go to 1,400 and after 30 seconds it goes to down to 700. At 60 kph the RPMs used to be at 1,100, now it is around 1,300 to 1,500. One more thing, when I turn the key off and start the engine again the RPMs goes to 1,000 even after driving (engine is warm enough). Not like before that at startup the RPMs go down immediately at 600. I am suspecting that the idle speed control is causing this. Anyway thanks and hoping for your most appreciated reply.
Tuesday, June 29th, 2021 AT 7:09 AM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Couple clarifying questions to start. What was done to fix the misfire? It is unlikely that this is related but we may just have another issue.

Here is a guide that talks about high idle as it will get us started:

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

Next we need to check for codes again and just make sure we don't have any new codes that would point us in the right direction.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Also, this doesn't sound extremely abnormal so it may just take a few hundred miles to relearn the idle and RPM now that the engine is not misfiring.

Below is the info on idle control and you will see that it is PCM controlled based on these inputs. So if there is an issue, I would hope there is a code for one of these systems to point us in that direction.

Lastly we may need to just do an ETC relearn which can only be done with a scan tool so we may need to seek a shop to try this if you do not have a scan tool that can do this.

Let's start with this info and go from there. Thanks
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, June 30th, 2021 AT 4:27 PM
Tiny
PAPET
  • MEMBER
  • 105 POSTS
Prior to the misfire on cylinder #2 (P0302), the #2 spark plug and #2 ignition coil were replaced and the code error was gone. But before the error code went on, I was driving to work one morning and after driving 20 meters away from home the RPMs suddenly went up to 2,000. Since then the RPMs had gone up. But when I turn on the ECON button, the driving rpm is back to normal. The only thing that bothers me is when I turn off the the engine and start again, the RPMs go to 900 to 1,000 even when the engine is warm enough. As of now there is no error code. The drivability is good and good gas mileage. Thanks.
Was this
answer
helpful?
Yes
No
Wednesday, June 30th, 2021 AT 5:17 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. So when the ECON button is on, it drives like it always did?

If that is the case, is there a chance that you used to always drive with ECON on and then it just got turned off and you noticed the difference?

The only reason is, if this is only happening when ECON is off then that is expected. This button is going to change shift patterns and RPM to improve fuel mileage as much as possible.

Clearly you are driving the vehicle and would know if there is an issue but if it is driving normally and fuel mileage is the same, then I would not worry about it at this point.
Was this
answer
helpful?
Yes
No
Thursday, July 1st, 2021 AT 7:12 PM

Please login or register to post a reply.

Related Engine Revs Up Content

Idle Air Control Motor Replacement
GUIDE
Idle Air Control Motor Replacement
The idle air control motor or idle speed control motor is designed to adjust the air flow into the intake manifold at engine idle. Engine idle speed is monitored by the PCM...
VIEW MORE