Transmission erratically shifts from 6th to 5th on a slight uphill grade CX-9

bryanm2bryanm2 Member Posts: 2
edited February 2015 in Mazda
My 2008 Mazda CX 9 jerks when going up a slight incline. I have notice it seems to be shifting erratically from 6th to 5th. I am not 100% positive on this. Sometimes I see the gear indicator shifting and at other times it does not. This could be simply that it is shifting faster than the indicator will show. Not really sure.
I took it to the Mazda dealer I purchased it from. They told me it needed to have some updates and needed the transmission flushed. They did this. Now it seems like it might be a little better, maybe not so violent but still doing it. It may not have done anything, it is really hard to tell. I called them back and now they say the fuel injection may need to be cleaned. It seems as though they are just using the process of elimination, which can be expensive. Seems to me a dealer should be diagnose an issue with much process of elimination if none at all.


  • sharkman73sharkman73 Member Posts: 1
    I have a 2008 CX 9 that is doing the same darn thing. This morning is was doing that again a lot, so I quickly toss it into manuel and it stops! This has to do with the transmission controller some how. I am actively looking for a solution. I did read something about sensors it uses to tell if the car is on an uphill grade or downhill. This is something I am trying to find more information about. Maybe this sensor is the issue? If I fix it I will re-post. Don't let the dealer nickel and dime you with "could be this". I have had the fluid flushed 4 times in my CX-9 and It now has 108K on it. If it was fuel injection or something engine side it would not clear up by putting the transmission controls into manuel! I have verified putting the shifter in manuel several times stops the jerks. So now when I get to hills I just put it in manuel because I am afraid all this jerking may actually damage something.
  • stern2stern2 Member Posts: 3
    edited February 2015
    I had an issue with my 2008 CX-9 at 100k miles when shifting from 6th to 5th or 5th to 6th. Not a huge issue just a small jerk when shifting. I thought it was a transmission issue or throttle control issue but no it was a spark plug issue. The plugs had not been changed since new and after I had the dealer change them and I paid the 300 or so dollars to have it done I no longer had the shifting issue. Not sure why replacing the plugs solved the issue but the gaps on the plugs were at about 80 thousand when removed and maybe the engine was missing slightly when the car was down shifting.
  • bryanm2bryanm2 Member Posts: 2
    Sorry for the delay in response!!!
    Thanks Sharkman73! I would be interested to know what you find. I find it strange that it could be fuel related because it really feels like a transmission issue, but it doing research I have found a lot of talk about it being fuel or fire related. Stern2, that is interesting, I was actually probably going to try replacing the plugs after hearing this somewhere else. I generally do this type of maintenance on my own vehicles, I wonder how much trouble it is? I once enjoyed doing it, but as I have gotten older it seems to have lost some of the 'joy'! On another note, someone with a different make/model vehicle told my wife their car was experiencing the same issue. They replaced the fuel filter and solved their problem. In doing a little research I have become a little puzzled as to whether or not this can be done on a Mazda 2008 CX 9????
  • laxmanchiplaxmanchip Member Posts: 1
    I'm having the same exact problem described here with my recently purchased 2008 CX-9. The dealer has tried updating/re-flashing the transmission software, replaced the tires, and done an alignment, but the issue persists.

    Other than the spark plugs being replaced, are there any other repairs which have resolved the issue for any of you?

    In addition, a new issue arose last week. The transmission for the vehicle was "sticking" in 3rd and 4th gears when descending a hill, even with my foot pressing down on the gas, and not shifting into the next gear until around 3000-3500 RPMs. Has anyone else experienced this?
  • MazdaGearProblemMazdaGearProblem Member Posts: 1
    2008 Mazda CX9 140k miles 5th and 6th gear change with severe hesitation/shaking that manual option had to be used.
    Changed plugs - corrected the problem
Sign In or Register to comment.