Ran fine when parked now will not idle

BRANDON ANTHONY

MEMBER
2006 CHRYSLER 300
5.7L
V8
4WD
AUTOMATIC
163,970 MILES

Just had a motor replacement 4 months ago. The motor was put in and had 82xxx miles, but the body has 163xxx. Its sat parked for 2 months after the motor was replaced. And now I have been driving it for 2 months. I have been driving it rough to be honest and so far all I've noticed aside from suspension wear would be between 30 and 60 mph under light acceleration it would shake like driving down a rumble strip on the road, and the motor would make a sound like it is bogging down but if I press the gas to accelerate faster those problems would stop. Not sure if that is relevant. But last night I got off work and drive 40 minutes with no new problems to a friend's. Shut the car off. 20 minutes later left to my girlfriend's 15 minutes away and got there shut it off with no issues. 10 minutes later went to leave go to start the car and it starts and the motor immediately starts to sound like a lawnmower running over a tree stump would be my description and shuts off after 2 seconds. I kept trying to start it and to even idle I have to press the gas but as soon as I lift it does and still sounds the same. After about 6 times I stopped. Tried again the next day about 5 times and stopped. All the fluids look okay except the oil. It was really low. So thinking maybe it ran out of oil and did damage I changed the oil to check for metal shavings in the drain plus but it was clear of shavings. Still does the same thing when started even with the proper amount of oil. I have checked fuel pressure at the fuel rail and it's good no leaks on the motor or damage to the under carriage. No surface issues that I can see. The issue does sound like its inside the motor in person. The kicker is the only code I'm seeing and that has been on in the car is for the oil pressure sensor. It has read 99psi on the evic menu since I got the car 2 months ago and the plan was to fix it this weekend until all if this happened. I can't afford to miss work and don't have tons of money to throw at this car. Can anyone please give me insight as to what is happening or how to fix it. My ideas are maybe the oil pump failed, or maybe jumped timing, or some safety feature kicked in. My diagnosing skills are minimal at best but I'm at a lot as to what to do. Sorry about being so descriptive but I wanted to have it narrowed down as much as I could. Please help. Thank you.

3 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi,

Just to break down the couple different issues.

1. The noise of driving over rumble strips is one of two things. First, this engine has what is called MDS or valve deactivation when the conditions meet. This is to improve fuel mileage and it will cause a drone noise and could be felt. When you press the accelerator it removes it from the 4 cylinder mode and the drone will stop. The other thing it could be is since this vehicle is AWD it has a transfer case. However, when your tires are not the same circumference then the AWD system will engage and due to the different sizes in tires the clutch in the transfer case will vibrate. Normally pressing the accelerator does not make this go away. It stops when you get past the speed in which it vibrates. Due to having AWD you cannot replace one, two, or three tires at a time. You must replace all 4 or you will hurt the AWD system.

The way to figure this out is to remove overdrive or downshift while it is doing it if you have the manual shift option. If the vibration stops as soon as you do this then that means it is most likely the MDS system because you are manually removing from the system.

2. The noise when starting the engine sounds like an exhaust leak. However, can you get a video of this so I can hear it because I could be way off? Thanks