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Discussion Starter #1 (Edited)
So I ran my car down to about a gallon of fuel, put in a full tank of 93 octane and pulled fuse 31. I left it out for about 10 minutes then did some spirited driving. The car felt stronger and faster. Is there anything to this or is it all in my head?
 

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It’s real. All the adaptive learning that the car does is erased when the fuse is pulled. The longer the period between pulls will give a greater sense of the difference. It has to re-learn your driving/throttle habits. If you drove it hard all the time, the perceived difference would be unnoticeable.
 

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Discussion Starter #3
I just read about possibly pulling fuse 29...transmission control module...at the same time as fuse 31. Anyone ever done this? If so, did it seem to improve the functionality of the transmission...faster shifts/holding gears longer....?
 

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As soon as you start driving again, it starts relearning your habits. It's a temporary thing. I suppose if you always drove at the limits it would stay there, but since most drive more "normal" most of the time, that's what it learns

A Guy
 
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So I ran my car down to about a gallon of fuel, put in a full tank of 93 octane and pulled fuse 31. I left it out for about 10 minutes then did some spirited driving. The car felt stronger and faster. Is there anything to this or is it all in my head?
Well, I'm in the minority but I'd say it is in your head. The engine controller constantly adapts to various inputs and seeks to deliver the torque demanded by the driver via the pedal at all times. This assumes there are no contradictory inputs for instance say from the knock sensors.

(Not that scientific but you can with an OBD2 code reader/data viewer connected and with short term fuel trims displaying remove the oil filler cap -- which is air intake leak -- and see the short term fuel trims immediately change under engine controller control as the engine controller adapts to the presence of un metered air. Then after a moment or two you can put the cap back on and observe the process again as the engine controller adapts to the absence of un metered air.)

In my experience with one of my cars I had a chance to fill up the tank with 93 rather than 91 which was only what was available to me in other areas and the engine showed a marked change -- for the better -- afterwards and I didn't have to pull a fuse first or disconnect the battery. In fact I have never pulled a fuse or disconnected the battery to force the engine controller to relearn.

But this is available to me by another method: Clearing an OBD2 error code, even if there is no active code, has the same effect. Among other things it resets the fuel trims to their factory default values and the engine controller will upon engine start, or if this is done while the engine is running -- though in some cases this is not advised, one can see the trims move +/- as the engine controller instantly begins adapting again.

AFAIK, for the transmission controller the OBD2 code clearing has no effect. There was a saying that the 1st run down the strip was for the "computer" to subject both the engine controller and transmission controller to the type of usage that was to follow so the 2nd and subsequent runs would (it was thought) not be burdened with the engine/transmission controller having to adapt during the run.

I know with my cars since OBD2 was present I never felt any engine or in the case of my Hellcat any automatic transmission needed any special treatment to adapt. When I put the gas pedal down in the Hellcat the engine is right now with the response and power. In automatic mode the transmission shifts appropriately. In manual mode Oh baby hang on. Likewise my JCW. I can putter around town then get to the freeway and have a nice long on ramp where i can open the engine up and the engine pulls like a beast right up to red line in as many gears as I can to use. I never felt the engine lacking in any regard.

Makes sense. The engine controller is there to with its population of sensors to constantly adapt to changing conditions to ensure as precise fueling of the engine as possible. It does this for every cylinder prior to every injector pulse and spark event.
 

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Discussion Starter #6
It very well could be all in my head.

It could be the pulling of fuses 31 & 29.

It could be the tank of 93 octane gas.

It could be the slightly lower air temperature.

It could be me getting better at getting the power to the rear wheels without significant tire spin.

It could be some combination of any or all of the above.

The bottom line is that I recorded a 5.2 0-60 (which is essentially a meaningless stat but it makes me happy) and I think a 5.0 is possible with more practice and the cooler temperatures of Fall fast approaching.
 

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I started a post about this years ago when I had my 2009 RT titled “pulling #2 fuse equals engine wake up call.” The before and after was palpable. Particularly in the throttle response arena. With a manual, shifting adaptives don’t apply. I would do this every few months. Curiously, with the 392 I’ve only pulled the fuse once or twice. I didn’t feel the same before and after effect as with the 5.7. I don’t drive my cars hard as a rule, so over time it “learns” to be civilized. I’m going to pull the adaptives fuse before my next ride and see what happens.
 

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This is definitely real! Pulling the fuse resets the "adaptaves" to maximum Factory settings. Drag Racers can see a half to a full tenth doing this depending on the way they drive normally. The idea is that if you drive less aggressive normally....the ECU rolls back things to a nice and smooth fuel efficient method. The other way to do it.....is to run it very hard several times in a row......this will "wake up" the settings to be more aggressive. Pulling the ECU fuse has been proven time and again both by 'seat of the pants" as well as detailed times. I have an unlocked computer that is tuned aggressively......both the Engine and Trans. I notice a difference pulling the fuse as well.
 
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It very well could be all in my head.

It could be the pulling of fuses 31 & 29.

It could be the tank of 93 octane gas.

It could be the slightly lower air temperature.

It could be me getting better at getting the power to the rear wheels without significant tire spin.

It could be some combination of any or all of the above.

The bottom line is that I recorded a 5.2 0-60 (which is essentially a meaningless stat but it makes me happy) and I think a 5.0 is possible with more practice and the cooler temperatures of Fall fast approaching.
LOL....nice post! Fall temps and air down to about 22 psi and u will see 5.0's! Pump up the fronts to max and have a 1/2 tank of fuel or less.
 
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I just read about possibly pulling fuse 29...transmission control module...at the same time as fuse 31. Anyone ever done this? If so, did it seem to improve the functionality of the transmission...faster shifts/holding gears longer....?
Where did you read this Rg21044 ? Interesting, Like when you activate the 'Sport Mode', the Torque converter locks up immediately in each of the gears ?
My Dodge Ram CTD does this in tow/haul node. It shifts to a new gear and almost immediately the torque converter locks up, in that gear. I dislike the 'squishy' feeling before the lock up.

Good information ! ( now I have to look for the fuse box,) Is it under the hood ?
Best regards
 

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The fuse box is under the hood, left side by the remote battery terminals


-2014 it's fuse #2

2015- it's fuse 29 for the TCM, and fuse 31 for the ECM

A Guy
 

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Same fuses for a 2016?
 

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yes, 2015 and up

2015-

it's fuse 29 for the TCM, and fuse 31 for the ECM

A Guy
 

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Discussion Starter #14
I believe I first read about fuse 29....tcu.....in a few older posts from this forum. It was also mentioned in some posts on "Challenger Forums" and referenced when others were describing similar fuse pulls with other makes and models like gen 5 Camaros with auto transmissions.
 

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Even with my unlocked computer and aggressive Tunes...this does not delete the "learning process" to your driving habits. The tunes just increase the maximum settings in areas that you tune. Driving easy for a while the Computer learns this and adapts and give you less aggressive settings...which makes sense.....cause they are not needed all the time. So...you can drive it hard a few times to "wake it up"....or just pull the fuse for about 10-20 minutes. I pull it when I arrive at the track while I am airing down the tires and blowing hot air with other racers.
 
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