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As title states, it seems randomly when I go to floor it the car will suddenly lose power around 4-5k rpm. I cant repeat it consistently and it happens in all different conditions (weather, length of drive ect).

When I notice it happens let off the gas immediately by reflex and never get a chance to look at the boost gauge. If I floor it again right after the car goes like normal.

Only mods are a cat back exhaust. Any idea on what could be causing it? When it happens it feels like the car just stops revving up and gets pinned at whatever RPM it happens at
 

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Sounds like one of the cars nannies kicking in and pulling power. I'll get that randomly as well, typically when it's hot outside.
 

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As title states, it seems randomly when I go to floor it the car will suddenly lose power around 4-5k rpm. I cant repeat it consistently and it happens in all different conditions (weather, length of drive ect).

When I notice it happens let off the gas immediately by reflex and never get a chance to look at the boost gauge. If I floor it again right after the car goes like normal.

Only mods are a cat back exhaust. Any idea on what could be causing it? When it happens it feels like the car just stops revving up and gets pinned at whatever RPM it happens at
I have exactly the same issue on my (completely stock) RS. Yesterday for the first time I managed to not get scared and kept the pedal down, to see what happens: the power picks up again and you can rev to 6000 rpm without problems, but at 4000 you're like 'what in the world is happening'. Feels like a rev limiter.

It's definitely not the issue of post #34 in the link of @Bob Loblaw. It's much more severe than this and only happens on full load, usually in 2nd or 3rd gear in Sport mode.

Figured out what the issue is after 2,5 years @ajh1717 :p ?
 

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Are you guys referring to the flat spot in the factory tune usually around 3.5k to 4.5k rpm?
I've heard of this a lot and had it on mine, but a tune sorted it out for me
 

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Are you guys referring to the flat spot in the factory tune usually around 3.5k to 4.5k rpm?
I've heard of this a lot and had it on mine, but a tune sorted it out for me
No, this is not just a flat spot in the power band. This literally feels more like hitting a rev limiter or having a few misfires at around 4k rpm. It's so blunt that like @ajh1717 says you 'let off the gas immediately by reflex'. It only happens occasionally.
 

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No, this is not just a flat spot in the power band. This literally feels more like hitting a rev limiter or having a few misfires at around 4k rpm. It's so blunt that like @ajh1717 says you 'let off the gas immediately by reflex'. It only happens occasionally.
The factory tune did that on my car. It feels like the engine pulls power for no reason at random times, sometimes you'd get full power and others it would start to build and at 3.5k the power would fall off. It would happen nearly every drive with the stock tune, and I don't think it's happened once in the 2 years I've had the M380 tune on the car.

The factory tune is garbage, it's a shame that Ford pulled the FP375 for those who care about the warranty. My opinion is that Ford limited the power because you can't have a 4-banger family car with faster 0-60 times than your V8 pony car...
 

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It might be what Ford performance calls "conditional boost".
If that's what you are experiencing, only a tune will fix it
 

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For me, this tip from Stratified helped with 4k rpm stutter at wot:

"AVOID getting into boost right away after you have cruised on the highway for some time. Downshift, ease into boost, build it gradually and then get into it. After this initial time easing into it, have a blast going through the gears!"

Else, new plugs help
 

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I believe my car has a similar issue and I may have figured out what it is. My car is bone stock other then a drop in filter and the issue started as soon as I flashed the Mountune Stage 1 tune.

It would act as some kind of harsh limiter or some sort of fuel cut for a moment right around 3k. Very jarring. Going back to stock would fix the issue and vise versa.

I took some datalogs of both stock tune and Stage 1. Here you can see that the Stage 1 (blue) has some distortions when hitting around 2700 rpm as opposed to stock which is smooth:
340328


I then compared the Stage 1 RPM vs Vehicle speed based on time to see if I could see some wheel spin. But other then a very small flat spot at the 35mph mark, nothing is standing out on that graph. I find it surprising that the RPM can fluctuate that much without affecting wheel speed. Might be slop in the drive train/sprung clutch.
340329


I then compared the runs in Virtual Dyno. It is very sensitive to wheelspin so I was not surprised to see the spike in power at 2700 rpm for the Stage 1 run. It might be wheelspin afterall.
340331


When comparing vehicle speed vs RPM for both stock vs Stage 1 using virtual dyno you can clearly see a small dip at the 2700 mark. This also seems to show that Virtual Dyno might be doing some noise cleanup in the background by getting rid of all log entries that have decreasing RPM values.
340330


I then had a aha moment when digging for the reason for the fuel cut feeling. I took a look at the ETC Angle Actual and saw that it was dipping drastically right at the right time or around 2700 rpm. However I was pretty shocked when I compared it with the stock tune that had an ever more drastic dip yet didn't show the symptoms.
340332

Finally one of my Stage 1 run, the 3rd back to back, managed to go all the way through without the hesitation. Maybe the tires warmed up. Here it is overlapped with the other stage 1 run along with the stock tune. You can see that the power doesn't shoot up like the blue line. You can also see that the vehicle speed line shadows the stock tune. Interestingly, that run saw the throttle closed even more drastically then the blue run yet didn't show the hesitation. I think it is safe to say it is not the source of the issue.
340333


In conclusion, I think this big hesitation might just be caused by wheel spin that the car less then gracefully try to keep at bay. I would like to see how it goes about it though. It is not evident by the PIDs I have went through yet. One more thing I need to try is to completely shut off traction control by holding the button for a few seconds. See if it helps. Unfortunatly I cracked the back of the engine block before I could diagnose any further.
 

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Great diagnositcs @Crazyced ! And thanks for the effort.

Although I'm quite (like, 99%) sure it's not wheelspin. It can happen at high speeds, and thus far I've never had in the rain.
 

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I believe my car has a similar issue and I may have figured out what it is. My car is bone stock other then a drop in filter and the issue started as soon as I flashed the Mountune Stage 1 tune.

It would act as some kind of harsh limiter or some sort of fuel cut for a moment right around 3k. Very jarring. Going back to stock would fix the issue and vise versa.

I took some datalogs of both stock tune and Stage 1. Here you can see that the Stage 1 (blue) has some distortions when hitting around 2700 rpm as opposed to stock which is smooth:
View attachment 340328

I then compared the Stage 1 RPM vs Vehicle speed based on time to see if I could see some wheel spin. But other then a very small flat spot at the 35mph mark, nothing is standing out on that graph. I find it surprising that the RPM can fluctuate that much without affecting wheel speed. Might be slop in the drive train/sprung clutch.
View attachment 340329

I then compared the runs in Virtual Dyno. It is very sensitive to wheelspin so I was not surprised to see the spike in power at 2700 rpm for the Stage 1 run. It might be wheelspin afterall.
View attachment 340331

When comparing vehicle speed vs RPM for both stock vs Stage 1 using virtual dyno you can clearly see a small dip at the 2700 mark. This also seems to show that Virtual Dyno might be doing some noise cleanup in the background by getting rid of all log entries that have decreasing RPM values. View attachment 340330

I then had a aha moment when digging for the reason for the fuel cut feeling. I took a look at the ETC Angle Actual and saw that it was dipping drastically right at the right time or around 2700 rpm. However I was pretty shocked when I compared it with the stock tune that had an ever more drastic dip yet didn't show the symptoms. View attachment 340332
Finally one of my Stage 1 run, the 3rd back to back, managed to go all the way through without the hesitation. Maybe the tires warmed up. Here it is overlapped with the other stage 1 run along with the stock tune. You can see that the power doesn't shoot up like the blue line. You can also see that the vehicle speed line shadows the stock tune. Interestingly, that run saw the throttle closed even more drastically then the blue run yet didn't show the hesitation. I think it is safe to say it is not the source of the issue. View attachment 340333

In conclusion, I think this big hesitation might just be caused by wheel spin that the car less then gracefully try to keep at bay. I would like to see how it goes about it though. It is not evident by the PIDs I have went through yet. One more thing I need to try is to completely shut off traction control by holding the button for a few seconds. See if it helps. Unfortunatly I cracked the back of the engine block before I could diagnose any further.
Check your plug gap too. I have been running out of car projects due to the stay at home order so I regapped the plugs (haven't touched them since new). 3 out of the 4 weren't that bad, but after regapping them there was a noticeable difference for sure, including a cleaner idle and smoother power delivery.
 

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Great diagnositcs @Crazyced ! And thanks for the effort.

Although I'm quite (like, 99%) sure it's not wheelspin. It can happen at high speeds, and thus far I've never had in the rain.
Could be, I'm still trying to spot the difference in the logs between the smooth runs and the rough ones.
Check your plug gap too. I have been running out of car projects due to the stay at home order so I regapped the plugs (haven't touched them since new). 3 out of the 4 weren't that bad, but after regapping them there was a noticeable difference for sure, including a cleaner idle and smoother power delivery.
Will do!
 

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Haven't had this issue since avoiding getting straight into boost after low RPM cruising, and renewing spark plugs every 15k

Here's a log with my 'hiccup'. Resolved with new plugs. Note I've had a better results with this issue on stock temp plugs.

340388
 
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