I bought this 2007 Jeep Liberty off of my friend in Jan. 2019 at 95,600 mi. It now has 113,500 mi. Last week, the check engine light came on when I turned the engine on as I was leaving work. I noticed the car was shaking/vibrating a little but decided to take it across the street to see if anything changed. The vibration turned into a violent shaking every time I accelerated so I brought it into a well rated shop less than a mile away. They gave me a full diagnosis, see image:
So I asked them to do front drive shaft, two lower control arms, and transmission coolant pipes. At the time, I didn’t realize the shaking was probably from the misfiring fuel injector but I found out as soon as I drove away and had them replace third cylinder fuel injector the next day. They also threw in a free alignment, new wiper blades, and a tune up for me.
Driving home, everything felt fine/better until I got on the freeway. At about 60mph, I noticed the car start vibrating slightly again, and it worsens with an increase in speed from there. Could it just be that I need to replace the spark plugs? Or should I look for another fuel injector to replace? For reference, this vibration issue didn’t appear to exist two weeks ago.
ALSO, for the past 5-6 months I’ve noticed this slightly high pitched mechanical whirring noise that would emanate from the front center of the vehicle during acceleration at low speeds, but in particular, it happened during acceleration during turns. After some research, I thought this may have been due to a historically leaky differential pinion seal resulting in a bad differential pinion bearing, which I thought would get fixed by the new drive shaft assembly. This noise still occurs occasionally when I accelerate at low to medium speeds. Although it is much more quiet and infrequent now and it doesn’t seem to happen during turns.
Any guesses for either of these problems?