My gts does a knocking sound every 5-10 sec while sitting in idle. While driving, when I let off the accelerator and the car is coasting, the car feels like it's trying to stop itself, especially at low speeds. When the car feels like it's trying to stop itself, I press the accelerator and it does the knock along with a little jerk. Happens a lot in parking lots. My gts has 192,000 miles and CVT transmission.

 

That could be a lot of things. I would guess something is worn in the drive line. Could be internal in the transmission or the CV joints. Do you get any popping noises when turning?

 

I don't believe I've experienced popping while turning. I'll have to check next time I drive. One thing I did notice is that when I start my car, sometimes it pops during the start up. When it does pop, the popping/knocking sound with the accelerator is more intense. When the start up is clean, it's almost nonexistent.

 

-Are you getting a check engine light?, Almost sounds like a spark plug blew out is cutting out. Could be rod knock/timing chain jump

-If you are saying it does this at start and idle then I don't think it's a transmission issue.

-If it's causing a loss of power or causing the car to slow down a bit than it sounds engine related.

-Get the car scanned to see if any codes pop up.

 

The only light that pops up is the service light, but it's because of a pressure sensor. Thanks for the help!