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Myth Busters - Fuse #2, Adaptive Throttle, Key Trick, ESP, Oh My!

25K views 50 replies 39 participants last post by  Matman 
#1 ·
I went on a test drive with a VERY knowledgeable mechanic (30+years) at my local Dodge dealer during a recent visit. He was very open for discussion regarding our Challengers. Here's what I learned: First, the Challenger is a great car, there are very few repair issues with the engine, tranny, and in general. He mentioned there was a problem with the 09s regarding a whining sound, but that's about it. I started talking about the mods I did so far. He said the exhaust sounded great, and definately provides a less restrictive path for exhaust gasses, and the CAI really does get more air into the engine, as the intake tube is much larger than the stock setup. So better breathing in and breathing out are a good thing for the Hemi. He mentioned that the Mopar CAI was designed specifically for this car to allow for significantly better air flow to the engine, and testing has shown increases in gas mileage of 2=3 MPG. Said he could feel a diifference, and he did get on it as we were on a freeway on ramp. So then I asked about the #2 fuse thing. He said that fuse does NOT reset the PCM settings for learning where the idle and WOT are, that could only be done with dealer tools (Star something??). He then stated there is no such thing as "adaptive throttle", the car never changes it's shift points based on how we drive, again, it only "learns" where idle and WOT are. And the "key trick" where you calibrate the pedal does nothing at all, you are wasting your time. So then I asked about predators. Absolutely these units can reset the shift points in fully automatic mode, but why would you want to when you can do that with the AutoStick, that is, shift when you want. I asked about warranty issues when using a predator, and he said generaly the dealer doesn't even care if you are using one, unless something is damaged, and the dealer can point to the programming as the cause. Ok, then we talked about ESP mode. He flat out asked me if I wondered why it's so hard to spin the tires on my R/T. So I'm like yes! Please tell me more! Well, it's hard coded into the PCM for safety reasons, and government regulations, and pressing the ESP button only changes the sensitivity a little. Same with the "trick" where you are rolling, and turn the key to start, lighting up the BAS and ESP indicators. I have verified this. No matter what combo of things you have set, the R/T is reluctant to spin her tires. Some pavements will let you, but in general, if you punch it from a standstill, you are not gonna spin the tires. My mechanic said it would take some serious mods to be able to do this. Doing a wheelstand is a sure way to light em up however.
I present this info as informational only, YMMV, I like all of you, want to separate fact from fiction.
 
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#2 · (Edited)
I don't know that I agree. 30+ years of experience on lots of cars doesn't mean as much as 2 years experience on the right car. These are pretty different compared to cars from 30 years ago, or even 10 years ago.

The transmission is adaptive, its a MB transmission that has these features. Thats a fact.

Tube length in a CAI doesn't seem like it would increase airflow... just the size of the tube around. Larger more free flowing filters do more than a CAI tube.

As far as ESP, I've only ever used the button off, and the Predator off. There was a difference for sure, and my SE with light mods will spin the tires a little on heavy take off with the ESP button half off mode. I'm not sure why you're having problems. if i want to tap the breaks I can smoke them, but due to the weight of our cars you wont get that kind of behavior off the stock cars. Need some serious power to kill a set of tires on a 4,000+ lbs well balanced car.

The fuse i'm not sure about, but enough people say it works, as well as disconnecting the battery and using the predator to reset it. This is the same for Chargers and all the other LX platform cars. If it really did absolutely nothing I'd think it would have been proven before.
 
#3 ·
On rainy days my 09 6-speed sounds like it's hitting a governor when tires start to lose traction. When I hit the esp button it is very easy to bring the ass around with full tire spin and full smile.

Every time I get in the car I hit the esp button. 25k miles in 13 months, daily driver even in the snow and I drive it like I stole it! Only reason I say wet roads, still have original tires on her and they still have a few more months life in em. Even with a few nice smoky burnouts on dry roads:bigthumb:
 
#4 ·
as far as esp off and the predator and not being able to light up the tires, even the throttle cal...........your (or your mechanic) is way off. Like left field in mexico way off. If you can tell and feel the diffrence.........well, I will leave it at that
 
#5 ·
If the mechanic thinks the Mopar CAI alone (or any CAI) is gonna give you an extra 2-3MPG he needs to go back for some refresher courses. I'd stay away from that garage.
 
#6 ·
The ESP off "Key Trick" does indeed work, at least on 6-speed cars. With ESP on my car will spin 'em for 10 or 15 feet and then engine power is abruptly cut off until it regains traction. With full off via the key trick it will spin 'em until it hits the rev-limiter.

I never noticed any difference with the throttle calibration reset either but then I drive mine aggressively. :thumbsup:
 
#7 ·
Can you do the "key trick" leaving the button in and holding it down? I'm too chicken to try.
 
#10 ·
I have the STP and no matter where I'm going, the first thing I do is disable the ESP. I wish it diddn't take 5 seconds to do so. In my GT, I can disable it instantly with the push of a button, even while on the fly.
 
#11 ·
Your mechanic is not well informed. The SRT engineers have stated on several chat sessions that the automatic has an adaptive transmission.

I have the MOPAR CAI on my SRT and fuel mileage has stayed the same.

Also, pulling the #2 fuse does the following:

All PCM DTCs erased.
All OBD2 monitor results erased.
All long term fuel trim adaptive values reset to Zero.

Your mechanic is "busted." :liar:


If you want a technical explanation about adaptives, read further:

In the case of the PCM, there are several types or "sets" of adaptive algorithms and the one
important one were are dealing with in this thread are "Fuel Table Adaptives".

The PCM has the ability to do some rudimentary fuel tuning (all modern OBD II vehicles now do this)
via "closed loop mode." Remember reading about how the PCM works?

It has two main modes of operation, closed loop and open loop. When the engine is Started and
heated up past 160 deg. F, the PCM now goes into "closed loop" control whereby it takes feedback
from sensors (i.e., IAT, MAP, O2, etc.) and looks at the fuel efficiency and attempts to tweak
out the current fuel tables to get the best MPG.

Tromping the accelerator to the floor puts the PCM into OPEN loop where it now goes to fixed
tables to do fuel mixture and O2 sensors are now bypassed while in WOT mode.

So where does this wind up over time? Well, there is a number of "learn cycles" that The PCM
goes into for fuel adaptives, normal 100 start cycles, or a "quick learn" of 50 start cycles.
During these times (cycles) fuel trim adaptive algorithms work on trying to get the best MPG.
After the 100 cycles, the MPG magic is pretty much done until something is done to initialize
another "learn cycle,"like clearing the memory by pulling the #2 fuse.

So if you have been driving around for a number of weeks, months "granny style" the
PCM has learned this and attempted to get the best MPG for you and tuned down (slowly)
performance. So, one day you tromp the gas hard or do some spirited driving and you notice the
car sluggish, or not quite as peppy as before.

Clearing out long term fuel table adaptives can help to make your car more responsive.

The PCM has a number of classes and types of internal memory. The fuel table adaptives are
stored in volatile memory and when the fuse (F2) is pulled for at least 20-30 seconds, this memory
is cleared and you can start over building a new set of Fuel Table Adaptive's for closed loop
control (next 100 start cycles).

The TCM (Transmission Control Module) for the NAG1 Automatic Transmission is another
animal however. It does nothing with fuel of course, but it does adapt somewhat to driver style
in how it shifts and operates. Look closely at the TCM write-up and note that driver adaptives
stored in the TCM are temporary and are written on a 10 min. sliding-window time period style.

Of Course, the standard transmission is manual control except for the skip-shift function, so I
guess you could say the only thing that would even might come close to being an adaptive there
would be its "skip shift solenoid function.

This would not be resettable as it uses a fixed set of reference points to operate.
 
#29 · (Edited)
The TCM (Transmission Control Module) for the NAG1 Automatic Transmission is another
animal however. It does nothing with fuel of course, but it does adapt somewhat to driver style
in how it shifts and operates. Look closely at the TCM write-up and note that driver adaptives
stored in the TCM are temporary and are written on a 10 min. sliding-window time period style.
Any links to elaborate on the above? I have been trying to figure out the programming on this for over a year so that I can 'trick' it to perform the way it should and the only way I have learned to trick it ends up costing me money in gas & tires and it must be performed in a safe area. :disgust:

IMOHO, this has been my biggest complaint as well as the throttle bog so any more info gained would be much appreciated! :thumbsup:
 
#45 ·
This was such a resourceful post..thanks for sharing your knowledge with us!!! Does it also help with the 6spds (fuse pull) I'd assume it does since its remapping fuel adaptive s and not tranny?
 
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#12 ·
great information there Cuda340. the good thing about the adaptives is they work both ways. if you drive like Mario Andretti all the time, the fuel/timing maps are set even higher. so if you reset the adaptive, it will feel slower. this is why i hate to disconnect the battery on my car. it has to relearn my lead foot driving style all over again.

i'm not 100% sure, but i believe that any time you flash the PCM, the adaptives are reset back to zero.
 
#23 ·
I don't think this is what it means... the adaptive fuel trim is basically the PCM learning how much gas the injectors flow per pulse, it already knows the "nominal" value hard-coded in the unit, but it looks at the O2 sensor and airflow into the engine to find exactly the flow characteristics of the injectors, which varies a little (manufacturing variance + any kind of deposits that form on the injectors)

I mean the PCM isn't going to give you a rich mixture or a lean mixture unless the engine is cold...
 
#13 ·
You can disable trac cont with the predator in dyno mode!!I will tell you it is alot different then just the button off.This week i was at the track and put it in dyno mode when i launched i lit up the tires right thru first gear(automatic).i have ran 10 times before and never once did that???You can also reset the adaptives with the predator???
 
#14 ·
As far as ESP, Just do your own test. Find a spot thats big, open, no cops. (warehouse truck yard). try to do a smokey burnout in normal TC on. Then try it with the button pressed once (try drifting you car this way) The comp will shut you down. Then try the key trick, If you have STP, hold the button down. Then try to drift it. I have a 09 with the NOESP mod. I think you will find the Key trick works fine. My mod showed the ABS was turnd off. I tryed both ways. With the TC off with the NOESP mod, I can flat-spot the tires at will. Can you say "OLD SCHOOL".
 
#15 · (Edited)
Re the ESP debate. For clarification, on the SRT the ESP button turns ESP completely off. On the R/T, the ESP button gives you a little more freedom but does not turn off completely. I believe the key trick is needed in order to turn it completely off. Just wanted to point that out.

Re the CAI. I lost 1 mpg after installing my Mopar CAI on my R/T. If you look at the factory airbox, it has a larger diameter tube than the Mopar CAI. The 6.1L CAI is a bit larger in diameter but still not as large as the stock box. Does the Mopar CAI help the car breathe better?? I dunno, I didn't buy it for that. I bought for the bling factor.
 
#18 ·
Re the ESP debate. For clarification, on the SRT the ESP button turns ESP completely off. On the R/T, the ESP button gives you a little more freedom but does not turn off completely. I believe the key trick is needed in order to turn it completely off. Just wanted to point that out.
....with the R/T, if you have the STP - Super Track Pack option, one push of the ESP button partially turns it off but depressing it for 5-10 seconds will disable it (you hear a chime and (those with EVIC) will show a message stating "ESP Disabled"). ....or (apparently) you can do the key trick.
 
#19 ·
I do know for fact that the key trick does work quite well on mine, and it will burn the tires at my right foots whim. I have never pulled fuse #2 as the car runs like a raped ape and has never felt "sluggish". I have not done the adaptive throttle trick as I am very happy with the cars throttle response. I did not experience any noticeable performance gain after installing the Mopar cold air intake. I am very aware of what is going on with my own car and how it responds to input. I don't hammer on my car and almost always I drive it at a normal level. On occasion I will jump on it of course and it is always ready and willing to tear one off. I love it! Get a new mechanic.
 
#20 ·
Your mechanic is BSing you.

I have had an SRT Engineer in my passenger seat, laptop hooked up to my car, running it HARD and can tell you that the fuse reset (on LX's it was Fuse 11) and Adaptive Learning are 100% valid.

Aside from that and the fact that the Engineers have talked about it openly in LXForums Roundtable discussions... any owners can tell you about fuse pull and adaptive learning.... why would he try to argue what we all already know to be true in our OWN experience???
 
#26 ·
This I find interesting. I had a custom dyno tune done by a well respected tuner known to many members here. I just inquired with him if the CMR tune he applied to mine blocks the adaptives and if not would mine benefit from pulling F2 ? His verbatim response: "Dont remove the fuse, adaptives are there for a reason". hmmmmmm
 
#32 ·
Which way are you turning it? You're supposed to turn it to the right, as if you were starting the car, and hold till the BAS/ESP lights come on. The radio and AC and such will shut off till you let go of the key.
 
#33 ·
Ohhh... to the right huh? For some reason I was turning it to the left, I think I read somewhere to turn it to the left :disgust: . Anyways! So turn it to the right and hold it while driving over 15 mph right? This doesn't hurt the car in anyway right? Thanks for the info!
 
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