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Ok, I was just told of a possible way to "tune" or "learn" our ECU's to get the most power out of our mods:

Take your car out onto the highway or somewhere were you can really open up the engine. Stop on the side of the road, turn the car off, pop the hood, and then take out the positive on the battery, and then touch it to the negative. This drains the ECU of all power and "resets" it. Then put the positive terminal back in, close the hood. Get in the car, get settled, and then as soon as you start up the car, put the pedal to the floor. In theory, this gets the ECU to "think" that the mods (intake, exhaust, headers) are stock, and therefore it repograms itself to utilize them to their full effect.

This came from a retired mechanic (retired about last year). According to him, cars come "de-tuned" to help put out better MPG (his example was the 300C, as it is rated at 340hp, but he claims you do this little trick, and it will put out nearly 400hp stock).

Any ideas from those mechanics here on the forum?
 

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2006 STS V8 AWD, '95 Ford Ranger
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As another engineer remarked when a similar strategy was described to him. "That's the most rediculous goddamn thing I ever heard". The "reprograming" or adaption process for the ECU takes place continuously, automatically, and methodically as required for the life of the car.
 

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Never heard of that one! Sounds like a good ole time playing with the electrical system. Needless to say I would not try this! Newer vehicles are capable of more horsepower than the advertised number. The makers put in Rev limiters, Torque management, Speed limiters, etc.. to ensure the vehicle's reliability and avoid potential damage to the powertrain. Some of us see these just as a big PITA.
 

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FAQ is your Friend
CTS-V
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That sounds like a load of BS to me...

What is true in that is when the battery dies (or is disconnected), the fuel trims (long term minor adjustments made by the PCM taking measurements) are reset inside the pcm which is why your car may idle funny for a little while after a battery dies... It will relearn these values over time...

Some guy probably tried what you mentioned above and he thought it felt faster when the car was running rich (standard LTFTs)...

I claim BS... Nothing you can do will make the car think all your mods are stock (unless you reporgram the PCM)... The car's stock program will adjust as best it can for all your minor mods anyway (by adjusting the LTFTs)...

E-mail stealthv in you want more information. I am NOT the expert...

Reed
 

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Cadillac Technician
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While that procedure won't really hurt anything all it will do is clear the memory, reset the fuel trims and the shift adapts.
It might drive differently for a few mintues but within several hours of normal driving it will just "relearn" the stuff it learned before.
 

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No problem, there is a lot of stuff floating around out there.
Some true, some lies. Sometimes it's hard to tell the difference.
For that there is this place :D
 

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The Mighty Kael, 2004 Black CTS, Every Option
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well there is actually some truth to this and has been done before, but not, i dont think on our cars.
for one, NEVER touch the positive to the negative, thats just nuts, ask the koz about chucking a wrench onto the posts and watch the arc show, thats a bad idea.

i have used this technique before on other cars but it is very limited and usually only for track days.
what we normally do is remove the positive lead for about 30 min to let the car drain and then reattach, this will let the power control module (PCM) reset.
you know how our cars and a few pervious generations will "learn" mods you make and adjust back to factory norms? well it takes the computer some time to do this, in the meantime it will load the default tables which are a bit more generous and on the safe side (running you a bit rich and such) and will work off of the current modifications without adjusting to them. this pretty much just buys you a few hours of a few extra horses.
the other way that this might have been twisted into an urban myth is if a user added something major to the car, like an intercooler, headers or other such heat management device. this has to do with the wonderful world of Knock Retard (KR) the car has sensors that will detect pre detonation (knock) and will pull timing from the car till that knock is not present, thereby saving your car. now if a heat management modification is made this will usually help (sometimes a lot) with pre detonation, but if you have not reset the pcm (or in our case the ECM) it will still command the same amount of timing retard (in some cars, every degree is worth 2-4 HP, our cars can go +/- 50), a reset will sometimes net "amazing" gains.
this is probably what you have heard about that has been diluted and trickled down through word of mouth and some not so savy people on the net.

-KL
 

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2003 CTS Manual Trans., '93 STS
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I don't know the details how the Bosch ECU learns to modify it's tables but I do know that it does learn and adjust to the mods based on fuel flow and air/fuel ratios, knock, etc. If one makes the engine more efficient by putting headers, high flow exhaust, CAI, etc, more air DOES flow in and out of the engine. To compensate, using O2 sensor readings among others, more fuel is injected to keep the stoiciometric 14.7 air/fuel ratio for emissions purposes. While this is not overly rich, the engine WILL make more power, as witnessed by my dyno runs of 200 RWHP (~250 at the flywheel) and Marine's ~250 RWHP (~300 at the flywheel). My dyno runs were done AFTER about 5000 miles with the mods on. Resetting the ECU may make it learn faster, but in the end, it will balance everything out.
 
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