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2010 cobalt downshifts when driving.....kind of


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x2jmorris
New User

Dec 18, 2016, 9:25 AM

Post #1 of 5 (383 views)
  post locked   2010 cobalt downshifts when driving.....kind of  

2010 Chevy Cobalt 2.2 I believe with about 50k miles. Front end salvage title too.

I noticed this every once in a while and have recently been paying more attention.

As I am driving around 75 mph and holding the speed. Sometimes as I get lazy and start to slow down it does like a surge almost. Like a downshift but quickly changes its mind and decides to stay in the current gear. I have only noticed it while going around that speed. It has also been cold lately here in MN but I want to say it did it time to time in the summer too.

Also, once in a while it will kind of surge while coming to a stop. Yesterday it did this and actually died. It is not every time.

I know this is hard to understand but I do not know what causes it. I don't think it does the surging at any other speed. It normally runs smooth.

I know very little about engines but I don't think it is transmission related. Maybe high idle for the stopping but why would it do it at 70 mph?

Is it normal? Any ideas?

Thanks for your time.


kev2
Veteran
kev2 profile image

Dec 18, 2016, 10:00 AM

Post #2 of 5 (379 views)
  post locked   Re: 2010 cobalt downshifts when driving.....kind of  

  Start simple easy
Scan for codes - yes even if light is off.
I bet we will see some codes... Let us know.


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Dec 18, 2016, 11:17 AM

Post #3 of 5 (374 views)
  post locked   Re: 2010 cobalt downshifts when driving.....kind of  

I would do as Kevin suggested and also monitor the transmission data stream to see if it is a TCC lock up issue.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


x2jmorris
New User

Dec 19, 2016, 5:50 AM

Post #4 of 5 (338 views)
  post locked   Re: 2010 cobalt downshifts when driving.....kind of  

I will let you know after I get it in.

Upon searching more it seems I am hoping for a vacuum leak in the fuel system or the Throttle position sensor. Hoping it isn't the TCC.


x2jmorris
New User

Dec 19, 2016, 5:59 AM

Post #5 of 5 (330 views)
  post locked   Re: 2010 cobalt downshifts when driving.....kind of  

Also noticed.

I have been getting low gas mileage for this car over the past year

It seems to only jerk when it is windy

By jerking I mean it seems like it is almost dying. I feel that when I wrote surge I was implying the PRM's went up. But it is actually the opposite.

And yes I will update when I get it in.

Thanks for the suggestions and ideas.






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