Shift to P Then Desired Gear and Throttle Body

[229Ready]

Vehicle: 2019 Ram 1500 Rebel Crew 4x4
Millage: 67,xxx
Issue: Shift to P Then Desired Gear and cold high idle and rough transmission down shifting after cold start.

Vehicle has a 5yr/75K MOPAR Vehicle Protection plan so is heading into the dealer for the Shift to P Then Desired Gear issue next week. Not having faith in the dealer, I decided to research potential causes. One potential cause was a dirty throttle body so I decided to inspect the throttle body.

To my surprise two of the four mounting screws were loose and hand tight. The loose screws were the ones in the front of the throttle body. After removal and inspection, there was a lot of carbon build-up. I used CRC Throttle Body cleaner and was easily able to clean it throughly. I reinstalled the throttle body and torqued all four screws.

I then completed a cold start 1.3mile 5 minute test drive to a complete stop. Max speed was 35mph. This drive when cold normally causes a high idle, rough down shift and then Shift to P failure, this time however the downshift was smooth and no Shift to P. I then drove an additional 5 miles with 5 complete stops and no issues.

It’s only a small sample but thus far I’m convinced the carbon build-up and loose throttle body was potentially the cause of the above mentioned issues that began at about 36k miles.

Picture is of temperatures during cold test drive. My recommendation is to check the throttle body’s. Hope this helps.

 

[BowDown]

Vehicle: 2019 Ram 1500 Rebel Crew 4x4
Millage: 67,xxx
Issue: Shift to P Then Desired Gear and rough idle and transmission down shifting after cold start.

Vehicle has a 5yr/75K MOPAR Vehicle Protection plan so is heading into the dealer for the Shift to P Then Desired Gear issue next week. Not having faith in the dealer, I decided to research potential causes. One potential cause was a dirty throttle body so I decided to inspect the throttle body.

To my surprise two of the four mounting screws were loose and hand tight. The loose screws were the ones in the front of the throttle body. After removal and inspection, there was a lot of carbon build-up. I used CRC Throttle Body cleaner and was easily able to clean it throughly. I reinstalled the throttle body and torqued all four screws and opted to add a little blue loctite. Not a fan of oil and gas additives but decided since there was carbon build-up in the throttle body, so I added a small bottle of Lucas Oil Injector Cleaner to the fuel.

I then completed a cold start 1.3mile 5 minute test drive to a complete stop. Max speed was 35mph. This drive when cold normally causes a high idle, rough down shift and then Shift to P failure, this time however the downshift was smooth and no Shift to P. I then drove an additional 5 miles with 5 complete stops and no issues.

It’s only a small sample but thus far I’m convinced the carbon build-up and loose throttle body was potentially the cause of the above mentioned issues that began at about 36k miles.

Picture is of temperatures during cold test drive. My recommendation is to check the throttle body’s. Hope this helps.

More than likely it was the unmetered air entering the intake manifold due to the loose TB, that will always cause rough idling because the engine is receiving air without any TPS input

 

[229Ready]

More than likely it was the unmetered air entering the intake manifold due to the loose TB, that will always cause rough idling because the engine is receiving air without any TPS input

Agreed. Was really surprised to find 2 of 4 screws not just loose but backed out and the throttle body as loose as it was. Hopefully this solved the issue.

 

[Scram1500]

Did you remove the loose screws all the way? May not have had enough thread locker or any applied at the factory

 

[229Ready]

Did you remove the loose screws all the way? May not have had enough thread locker or any applied at the factory

I did because I cleaned the throttle body. When I reinstalled it I torqued them all in a crisscross pattern. The manifold is plastic so you have to be careful over tightening the screws and shouldn’t use thread locker for metal. Also the screws are completely coating in some type of green paint I assume for keeping them secure.

 

[bigwidge]

I did because I cleaned the throttle body. When I reinstalled it I torqued them all in a crisscross pattern. The manifold is plastic so you have to be careful over tightening the screws and shouldn’t use thread locker for metal. Also the screws are completely coating in some type of green paint I assume for keeping them secure.

I'm having the same issue. Did this completely fix the problem?

Also, would you mind elaborating on the steps you took to clean the throttle body?

 

[sparker417417]

I'm having the same issue. Did this completely fix the problem?

Also, would you mind elaborating on the steps you took to clean the throttle body?

I'm in the same boat. 19 Laramie with 100k and did it twice today and been occuring more and more.

 

[bigwidge]

Sorry to revive an old thread- but this issue is still ongoing for me. Cleaning the throttle body makes my truck run GREAT for a day, but the issue quickly returns. Since February 6th, I have cleaned the throttle body a total of 5 times. I remove the hose coming from the air filter, clean the butterfly valve with Throttle Body Cleaner and wiping all areas with a towel and working the valve back and forth, and then put it all back together. Are there any other suggestions I can try? Should I be looking at replacing the throttle body itself? It seems to be happening more frequently now. I'm talking 1-3 times for each daily commute (20 min drive), when I am approaching a stop - typically one that's at an incline.