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Discussion Starter #1
I have read many post/threads about pulling fuses 29 & 31 to improve the performance of my 2017 Scat Pack. There are several responses that advised against doing this as it may store false codes, could cause a static short on the fuse box board and other issues. One person ( an auto tech from a dealer if memory serves) had a lengthy post with a long list of the reasons why not to pull the fuse, but I am unable to locate his post to ask these questions. Is the problem just with pulling the fuse? Would disconnecting the battery to cause a reset be a safe alternative to pulling the fuse? Do neither and just drive the car hard and let it learn a new driving "profile" over an extended period of time? Thanks for any information on this subject.
 

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The Bacon Hauler (‘12 Cop Charger)
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I would advise against pulling the fuses in an attempt to "improve performance" of the car. All it is doing is resetting the fuel trims and transmission adaptives, both of which should improve performance on their own if given enough time.

Resetting them only makes the PCM start over from scratch trying to figure out where they should be set to provide the most optimum performance for your engine, the fuel you run, and the way in which you drive.

Why are you wanting to do this anyway, do you feel the car is lacking in performance lately? Can you literally feel it not accelerating as quickly as it used to?

If the answer is yes, you're likely feeling the effects of the PCM pulling spark timing in response to knock (KR, aka Knock Retard) in the combustion chambers. There can be many reasons for knock, but the most common is inadequate octane for the conditions in which the car is being operated.

The easiest way to check for something like this to use a handheld tuner to datalog a WOT run and look for KR spikes, but if you do not have a hand-held tuner, I would say just fill up with some 93 octane and go do some 0-60 and 55-100 mph runs.

If the original problem was due to KR, you should hopefully not feel that anymore (and you can definitely it when the PCM is pulling spark, it's as if something is holding the car back from accelerating even though it's really, really trying). If you still feel it, the problem is either not KR or the knock is being caused by something besides insufficient octane.
 

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Discussion Starter #3
The car performance is fine. I am the second owner, so I was wondering if the previous owner driving habits were preventing me from seeing what the car's full potential could be. Based on what many have posted here and on video they seemed ( placebo effect possibly ) to notice a performance improved when pulling the fuse. Thanks for the reply.
 

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The Bacon Hauler (‘12 Cop Charger)
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Pulling the fuses will reset the fuel trims, which means the engine will run a little rich at first while it relearns the engine's necessary air/fuel mixture adjustments. So in a vacuum, that time spent running a little richer while it relearns everything might seem like the engine has perked up, but in reality it not running any better than it did; only different. I think that difference is what most people mistake for running better.

Once the PCM has the fuel trims pretty well figured out, that is theoretically the best the engine will run; period. Resetting them at that point just means it must spend time running less efficient to figure them out all over again.

Plus, everything you reset by pulling the fuses is all non-WOT operation of the engine. WOT of the engine depends upon preset tables of values in the computer which will not be reset or modified at all without a custom tune. And since you're probably going to be going WOT any time you are judging how the engine is running, the whole fuse-pulling thing won't even affect that time spent driving the car.

I'm not saying you cannot do the fuse pull thing; I'm just saying you will not get a 'better' running engine by doing it. Different? Sure, but not better. In fact, it's likely to run a little less efficient for the time being, which could even translate to 'worse' running in some cases...
 

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Pulling the #31 fuse just at the track, for a few minutes, works in that it now only seeing WOT and corrects...That and putting in some higher octane fuel does seem to help my car there...Just me...Not saying you all should...
 
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