Rev limiter or fuel cutoff before A10 shifts

[MidLifeManifustang]

I noticed on a recent road trip when flooring the throttle to pass (and then keeping it pinned a bit for fun) that my automatic transmission will downshift as expected, then shift nicely at close to redline for the next couple of gears up, then NOT shift until after the engine power is suddenly cut for a second or so. The car noticeably slows as this is happening and it’s disconcerting. I haven’t yet had a safe-ish opportunity to keep my foot in it to find out if the same thing would happen near redline in the next gear.

It feels like the transmission is forgetting to shift until it’s too late.

To be clear, I’m not touching the paddles at any point and the shifter is in D.

It’s going pretty fast when this happens so I’m watching the road, not my gauges, but I think it’s occurring at 95-100 mph, well short of the speed limiter. It does continue to accelerate after the cutoff and subsequent (delayed?) upshift.

It happened at least 3 times in normal mode and another time in Track mode.

Has this happened to anyone else? If so, did you figure out which gear it was happening in? Did you find a fix? I’d like as much data as possible if the dealer has to get involved because I’d rather they not have to replicate the problem with a road test.

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[24grabbergt]

this happens for me daily, my work is in the middle of nowhere on a long straight highway. speed limit at 65 but 18 wheelers run 80 so you have to pin it and the same thing happens exactly as you described.

 

[roadpilot]

I’d rather they not have to replicate the problem with a road test.

You think they are going to work on an issue without replicating the problem? Under warranty? Lol. That's not how the process works.

Regardless ... call me crazy, but I would simply tap the upshift paddle.

 

[Q6543]

What you're noticing is most likely the throttle bodies closing in the upper rpm, it’s programmed into the GT, less so on DH.
So either upshift or feel it rollover.

 

[MidLifeManifustang]

What you're noticing is most likely the throttle bodies closing in the upper rpm, it’s programmed into the GT, less so on DH.
So either upshift or feel it rollover.

No kidding? What would be the point of this? And why only in that gear?

 

[Q6543]

No kidding? What would be the point of this? And why only in that gear?

to prevent the GT from having the same HP as a DH.

 

[Sf22giants]

to prevent the GT from having the same HP as a DH.

There is significantly more going on than just “make less power cuz it’s a GT”. Yes, the GT is programmed to make less power but it’s also programmed to do a bunch of different things than the DH and even the S550 GT. For what it’s worth, the DH does not have the same shifting issue in any gear or any mode while in D, but it will let you rev to red line in M and the transmission will hang at the top of the gear of you don’t manually shift. While hanging at red line, the car will modulate the throttle, as if you’re in neutral, until the shift occurs. This isn’t OP’s problem but it’s the only way to force the DH to do something weird via the transmission.

Take a glimps into some of the things that are different between the DH, GT, and the S550 here:

Credit to Palm Beach Dyno for walking through the S650 data as best as possible in a video format.

To address OPs question: there is absolutely some type of modulation happening. It’s possible that the issue rests with throttle position, transmission speed, timing, something totally different, and/or a combination of all of the above. To actually know what it is, the vehicle has to be data logged and then reviewed. Without a data log, you can’t really see what’s happening, as it’s happening.

I don’t know what Ford would do other than pull codes. If there aren’t any, they may just send you on your way and not do anything about it.

 

[MidLifeManifustang]

to prevent the GT from having the same HP as a DH.

Thanks, but what you’re describing isn’t the explanation for what my car is doing. It’s not just a subtle rolloff to keep 486hp from becoming 500hp— the engine is literally having its fuel or spark cut entirely for about a second, going from 486hp to zero.

 

[Q6543]

Yes. The throttle bodies are closing.
https://www.facebook.com/share/r/4SPVJAH3GaPFfejd/?mibextid=xCPwDs
Lidio explains it better than me.

 

[drive_55_not]

Thanks, but what you’re describing isn’t the explanation for what my car is doing. It’s not just a subtle rolloff to keep 486hp from becoming 500hp— the engine is literally having its fuel or spark cut entirely for about a second, going from 486hp to zero.

I captured that happening on a data log last week, In my case It feels like it's hitting a soft limiter, Just get a milli-second power cut at the shift., Not a full-on nose over like you hit the hard limiter.

Log shows timing going negative and fuel pump is also being cut.

I presume it's some kinda torque management kicking in.

I was testing an E40 mix and it was a balmy 65 at 4am when I made that run.

I've logged Ethanol Free 89 and had no issues with it, but it was in the low 90's when I made that run.

That video looks like they have something else going on.

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[Q6543]

@drive_55_not

what software or device do i need to datalog mine please?

 

[drive_55_not]

@drive_55_not

what software or device do i need to datalog mine please?

SCT BDX or HP Tuner MPvI3

I have both but like the SCT LiveLink display better.

With the LiveLink the channels are listed and you just select or deselect from there.

You can borrow one and log with either, My BDX is still married to my 2018, I can log with it but it wont load a tune without being unmarried.

The HP Tuner VCM Scanner will log without needing to buy credits.

If you're buying one I'd get the HP Tuner, If they ever unlock the PCM HP Tuners will have more tuning cells available.


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[robvas]

@drive_55_not

what software or device do i need to datalog mine please?

edit: beaten!

His screenshot is SCT livelink and Lidios looked like HPT VCM scanner

 

[Sf22giants]

HP Tuner also has some good user guide YouTube videos on how to use it with mustangs. I’m not a tuner but I can understand the HP interface

 

[revinto7]

my 2018 A10 performance pack does this 50% of the time on the 1-2 shift its not as common or as bad but the 2-3 shift it is like it forgets to shift then noses over and then shifts ..no ryhme or reason for it .its much less in drag mode but it happens mostly on a dig run from a stop .. im thinking the rev limiter and shift point are to close ...

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