Blip in acceleration?

[PandaST]

So I’ve noticed something with my ST, and now that I can’t un-notice it, want to see if its normal. When I’m coming up to speed, somewhere around 30 MPH there’s a very brief hesitation in acceleration (the RPM drops for a split second too). It’s almost like a gear shift, but doesn’t seem pronounced enough to be that. I THINK it’s a little less noticeable if I’m driving agressive or the other way in Eco mode.

Is this normal? I’m not familiar with the 10spd transmission and haven’t had a turbocharger since my teens, so not sure if it’s a quirk with either of those.

Thanks for any help!

 

[F=MA]

I have not had any issues like that in three different 2020 ST's. Could be air, fuel or spark. Off to the dealer she goes for a 6 week vacation.

 

[GearHead_1]

I have no idea but I’d wonder if it isn’t really transmission strategy issues.

Sometimes it’s simply related to the owners driving pattern, sometimes the trans can be reflashed and help things out.

These 10 speeds take some getting used when skipping gears etc. If that happened to be it a good tuner that knows it stuff should be able to help you out.

I see lots of people on truck forums complain about how hard it is to get used to how these transmissions skip a gear on an up shift. The fact that your RPM’s drop when this happen would seem like it might be worth looking in to.

 

[kkriskal]

If it only happens at one particular speed, I feel it cannot be related to fuel pump/air etc. It might be just how the transmission is shifting at point. On the other hand, if you notice it randomly under various scenarios, then the pump/air etc. comes in to picture.

 

[mwinn]

So I’ve noticed something with my ST, and now that I can’t un-notice it, want to see if its normal. When I’m coming up to speed, somewhere around 30 MPH there’s a very brief hesitation in acceleration (the RPM drops for a split second too). It’s almost like a gear shift, but doesn’t seem pronounced enough to be that. I THINK it’s a little less noticeable if I’m driving agressive or the other way in Eco mode.

Is this normal? I’m not familiar with the 10spd transmission and haven’t had a turbocharger since my teens, so not sure if it’s a quirk with either of those.

Thanks for any help!

Have something similar. Around that speed, maybe lower, under light acceleration (normal mode) there is a slight hesitation and what sounds like a humming coming from the front. Quicker acceleration or in sport mode, don't notice it, FENG my drown it out. In shop now for other things as well. Will report findings once I get her back.

 

[jpm2988]

If I am not really into it the transmission will do a 1-3 and then a 3-5 shift. Power will be pulled out of the motor temporarily to make the shift smoother. I have the same 10 speed in my F-150 with the Coyote 5.0 in it and it also shifts that way. If I am into it, or in Sport Mode it doesn't pull the power.

 

[Lightning Struck]

If I am not really into it the transmission will do a 1-3 and then a 3-5 shift. Power will be pulled out of the motor temporarily to make the shift smoother. I have the same 10 speed in my F-150 with the Coyote 5.0 in it and it also shifts that way. If I am into it, or in Sport Mode it doesn't pull the power.

Your F150 has a 10r80, the ST has a 10r60.

The hesitation could be a couple different things. It could be the torque convertor locking up, or torque management pulling timing for the shift. I wouldn't really worry about it

 

[PandaST]

Thanks everyone! I'll keep watching it to see what happens. Hope it doesn't result in a trip to the shop, but sounds like it might be a somewhat normal thing.

As far as tuners go, do they void warranty? I was thinking about buying an extended one.

 

[kkriskal]

If I am not really into it the transmission will do a 1-3 and then a 3-5 shift. Power will be pulled out of the motor temporarily to make the shift smoother. I have the same 10 speed in my F-150 with the Coyote 5.0 in it and it also shifts that way. If I am into it, or in Sport Mode it doesn't pull the power.

mwinn, I have the exact same thing in my ST as well. The same light hum noise and that blip while it shifts gears, only under light acceleration ( I have this bad habit of babying my vehicles). Any acceleration over 2K RPM it is not noticeable while it shifts gears.


jpm2988 and Lightning Struck, Thank you so much for clarifying/explaining this. I have been breaking my head for a week now test driving my ST like a mad man on quiet roads replicating it and getting more and more worried. Your clarifications give me a lot of peace.

 

[mwinn]

KKRISTAL, thank you for the insight. Your explanation makes sense. The Explorer is quiet especially at cruising speed and below where the FENG kicks in. Mine is still in the shop awaiting parts for the other issues. I've found this site very insightful (and a little entertaining at times). I often use some of the information here to help communicate with the service advisor. I'll report back once she comes home.

 

[kkriskal]

KKRISTAL, thank you for the insight. Your explanation makes sense. The Explorer is quiet especially at cruising speed and below where the FENG kicks in. Mine is still in the shop awaiting parts for the other issues. I've found this site very insightful (and a little entertaining at times). I often use some of the information here to help communicate with the service advisor. I'll report back once she comes home.

Thanks mwinn. Yes, this forum is very helpful and the members are so knowledgeable (unlike me) that I have avoided so many trips to the dealer. Imagine, if this thread was Not there, I would have let my dealer test my vehicle for no reason by multiple techs there and creating a new problem.

I was originally discussing this in another thread but that thread was for a different issue. Luckily I found this thread which was the exact thing as what I was experiencing. Here is the detailed test result that I posted earlier in the other thread.

After extensive testing in isolated/quiet roads near my house (had to go do this in the night so there was no traffic).

1. First of all, to give a background, I generally baby my vehicles most of the time. I do open in up once in a while depending on the open road and my mood etc.
2. So I give very little gas when driving (because of my babying habit), which means that most of the initial gear shifts maybe upto 4th gear happens with the RPM less than 2000
3. Under the above conditions, I see that the engine is revving/increasing RPM to accommodate the gear change since it is too low (I can see the RPM go up and then down during the gear change). this automatic blip in RPM is the noise I hear which is basically the engine rev
4. So I decided to test it by driving like a normal human being and gave sufficient gas which made all the shifts at or over 2000 RPM, in this scenario, I do Not hear that noise (that hmmm kind of noise) so basically meaning that the engine has sufficient RPM to accommodate the gear shift without the software having to rev it any further.