Hey guys, I am a new owner of a 3rd Gen 04 TL Base model. I've only had the car for about 3 days. Within these days, I have noticed a bit of a jerk when shifting or at low RPM's when accelerating. As I drive, I could feel the car jerk back and forth. At low RPM's, I would get it up to 2K RPM's, before it shifts, it would drop to 1800 or 1900, and then go back up and then shift into it's next gear. Weird I know. At 45+ MPH, I won't feel the jerking as much, but at speeds under that, it's pretty noticeable. Any suggestions on what it might be?

- According to the owner, the 3rd and 4th gear sensors have been replaced already.

 

Whoops, bad grammar, I meant "According to the previous owner.."

 

How many miles on your car? And when were the sensors replaced?

 

112.5k miles. They were replaced around 90-95k miles when he took it in to get the major service repair done.

 

I had the same problem with my TL last year. I felt it jerking and it was weird shifting gears for a while. After ignoring it for a few months it got worse and I would end up gassing it without moving (RPM would shoot up but I would go no where) as if I was in neutral. It turns out my gears were broken and they were slipping off each other. Long story short, I had to get my whole transmission rebuilt. So if I were you I would go and get that checked before you spend $5000 fixing it. I mean better not then later. At least that's my story.

 

It's normal, especially under light acceleration to have the rpms drop slightly, rise again, then shift. The torque converter has slip. When the road speed gets high enough for the gear you're in, the converter clutch locks up, giving 100% couplilng like a manual and the rpms drop. This is done for gas mileage.

That part is normal. What isn't normal is feeling a jerk when it happens. At least one of the switches have some control in the TCC lockup but you said those have been replaced already. The fluid can have a big effect on how it locks. I would start with changing the fluid out. Any Dex III fluid will work well or stock DW-1.

So you're not feeling a shudder, just a jerk before it shifts gears?

 

Yup, just jerks, no shudders.