Managing or tuning out - "Rev-Hang"

759-OR

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So just pulled the car out of storage, getting it ready for this season.

Driving it around I am remembering all this things I was supposed to fix over the winter. The most annoying being the fact that it holds onto revs when I take my foot off the throttle. I mean REALLY holds onto revs. Manual trans 2012 BTW... :)

My research shows that this is normal for this car, and that it's an emission thing. Fine, but it was damn near dangerous at the track, not having the compression braking I was expecting.

Around town, I can take my foot off of it and coast seemingly forever. RPMs drop VERY, very, sloooooowly.

Anyway, I have a Steeda tune, which is great. I wrote those dudes a note, and I haven't heard back, but I am sure I will. No difference between stock and Steeda in terms of the rev hang going back and forth. No stored codes or anything weird. Car is stock except for sound tube delete and mufflers.

Wanted to reach out to the hive mind and see how you all are managing this. And if what I am describing is normal.

Thank much!
 

stkjock

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It’s the dashpot setting
 

MrAwesome987

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My 09 does the same thing with a bama tune. I complained to bama and they had me datalog the car. They responded to the datalog telling me it looked fine.

It's really annoying, and even more annoying with the AC on for some reason.
 

759-OR

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Had a nice chat with Steeda today.

I sent them a data file with some throttle chops and 3k, 4K, and 5k RPM.

I told them I wanted it to engine brake like a carbureted motor. And they seem to think they could accomplish that.

Will keep you all posted.

:)
 

nyuk98GT

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759-OR,

I'm keen to see the response from Steeda.

Not much help other than a little personal experience to share.

It’s the dashpot setting

Fearless Leader is quite correct. Dashpot adjustment will do the trick.

I used SCT's ProRacer program to tune my '98 GT and took care of things like: adjusting the dashpot to get rid of "rev hang", dropping the RPM adder at cold start, dropping most of the idle clips, and widening the active range of coasting fuel shut-off for engine braking. Little things like this make a big difference in improving the time behind the wheel, imo. (I took care of 268H cams, a PI intake, and the 4R70W shift and lock schedules, too, but they were bigger stuff, lol.)

I am certain that Steeda can do whatever you want - maybe at a nominal cost. They're in business and ought to respond to market demand with some nice features in their tune to differentiate theirs from others. (They frequent the forums and see posts like yours.)

HTH,

Chris
 

759-OR

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I sent a datalog to them earlier this week so they could see what was happening.

It seems to be with their Lead Tuner at the moment.

They are a busy group, and this is an old car, so I can't see them rushing right on it.

But they seemed pretty confident they could fix it. And I'll just keep you all posted.
 

1950StangJump$

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When I had a 2011, it didn't do this NA. Then, with the Roush blower and VMP tune, it did. At that time, VMP told me it was not a tune issue. Sold the car (for other reasons) before I really addressed it.

My current daily driver is a stock 2017 Fiesta ST. It has the ecoboost and it hangs EVERY SINGLE TIME since brand new. I always assumed it was tuned that way either to act as almost a rev matching feature, or it was to mitigate shock to components.
 

Norm Peterson

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Far as I'm aware, rev hang is always done for emissions reasons, to reduce or eliminate an emission spike (HC?) that happens when the throttle is sharply closed.


Norm
 

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