will taking neg battery terminal off make my stereo not work

[cj_sx_2011]

hey all ive been told to take the negative battery terminal off to re calibrate the computer, but will it make a code come up on the headunit and need to put a code in for it to work again?

im only asking coz when u took the battery terminal off in my old car u had to put a code back int to make the radio work again,

someone please let me know thanx.

[feral]

No radio code but you will have to set stations clock and Bluetooth when you reconnect

[cj_sx_2011]

thanx man, um how long for to keep it off? 5 mins?

[The X]

I think the manual says 15 mins, should be more than ample.
Enough to reset the ECU to "re-learn" your driving style and adjust the maps/profiles accordingly.

[cj_sx_2011]

oh okies, thanx pete, i only done it for 5 mins

ill re do it again, but for 15 mins.

so what do i do after the 15 mins? do i just turn the car back on, and how long do i leave it to idle for? or do i go for a drive?

thanx

[LZY_EYE]

Just drive it... the ECU will learn regardless of taking the battery terminal off... Taking it off might speed up the process a bit

[cj_sx_2011]

thanx Lindsay, and thankyou for that shane

[Cammo00]

no code all set to chassie number im pritty sure.

[The X]

oh okies, thanx pete, i only done it for 5 mins ill re do it again, but for 15 mins. so what do i do after the 15 mins? do i just turn the car back on, and how long do i leave it to idle for? or do i go for a drive? thanx

Our cars apparently "learn" and "adapt" to the driver's "driving style" - so "resetting" the ECU, puts it back to factory defaults and it will learn and adapt all over again from scratch.
After the 15mins, connect the terminals, and leave the car there for a week if you want. It won't learn anything.
If you want it to learn your driving style, take it for a spirited drive somewhere appropriate.

I guess for us to get a clear idea of what you're trying to achieve, why are you trying to re-calibrate the computer? someone's told you something, what is the goal you are chasing? We might be able to help or dispell some myths for you.

[cj_sx_2011]

ppl say different things,

i have an exhaust right, so im thinking, im getting the stock amount of air in, but exhaust gas is going out quicker then the stock exhaust, so i thought it wouldnt be working aswell as it would as stock,

so me thinking, by doing the battery thing, it would re calibrate but letting more air in to match the exhaust going out quicker

so that was my thinking behind it. im probably wrong

[Dirtee]

I think the manual says 15 mins, should be more than ample. Enough to reset the ECU to re-learn your driving style and adjust the maps/profiles accordingly.

Doesn't affect the MAPS that were put in by a tune right..?

[sleeper]

no, it doesnt change the "tuned" maps

[LZY_EYE]

ppl say different things, i have an exhaust right, so im thinking, im getting the stock amount of air in, but exhaust gas is going out quicker then the stock exhaust, so i thought it wouldnt be working aswell as it would as stock, so me thinking, by doing the battery thing, it would re calibrate but letting more air in to match the exhaust going out quicker so that was my thinking behind it. im probably wrong

You can only get at much air in as you get. The engine does not suck air in as such. That is why you have a snorkel etc to force the air in when driving. The car will adjust the fuel according to what is detected on the air flow meter.

The car should perform a little better after the exhaust is done because it is freer flowing. To be honest, if you left the car over night after having the exhaust done and took it for a drive you will get the same result as removing the battery...

[debonaire]

Of course the engine sucks air in... the piston moves down, a vacuum is created, and air is sucked in to fill it.

I've seen studies that show having a forward facing intake to 'force' the air in made no difference, all that matters is that you aren't taking in hot air.

[Glenn]

[quote:cafe6a0914=VRX_Pete]I think the manual says 15 mins, should be more than ample. Enough to reset the ECU to re-learn your driving style and adjust the maps/profiles accordingly.[/quote:cafe6a0914] Doesnt affect the MAPS that were put in by a tune right..?

disconnecting the battery will reset the long term and mid term fuel trims which are used in closed loop operation - normal driving - the closed loop AFR for example is 14.7 so regardless of whats in your map, tuned or other wise, its going to tell the injectors to "add" x% so that you hit 14.7 when driving in closed loop, cruising etc - which is determined by the mass airflow sensor.

Now for the stock ecu/tune, LT fuel trims do affect wot afr - so when you punch it, the car will use your maps but will also adjust fueling based on what it had to do to keep things happy while cruising.

So if you got tuned and your fuel trims where +/- 5%, you then reset the ecu, you'd see a bit of difference (either rich or lean) for i think its 20-40min before the fuel trims returned to where they were. which they should assuming you didn't modify anything in between. So you wont be losing your Merlin tune Tim!

Simpler way to reset the ECU is to pull the ecu battery backup fuse


I agree though, if you change the exhaust, either resetting the ecu or driving the car for a day, you'll end up in the same place ecu wise. Yes the car will adapt to it for closed loop idle and cruise, but its not going to tune itself for the rest of time when your accelerating etc.

To the point about exhaust/intake flow,
Stock amount of air in is lower than it could be due to the stock exhaust.
You could have the biggest fanforced turbocharged soup'd up intake but if that same air cant leave the engine via the exhaust, the whole thing backs up. By opening up the exhaust, you unlock the potential air that could be going through the stock intake. Since the stock tune (fuel maps) are typically super rich (more fuel than air) by you opening up the exhaust which inturn opens up the intake/overall air flow, when ecu gives its instructions to all the mechanical systems (injectors etc) to get a AFR of say 9, its going to get that extra little bit of air so the actual AFR will be more like 10. This is why most intake/exhaust upgrades give that power benefit without really even needing a tune! Sounds pretty good! But imagine if the car was/is tuned at the limit and you then added on a exhuast!