Disconnect battery for ECU reset...

23rd December 2008, 21:34

Basically, I want to reset my ECU by disconnecting the battery. My questions are;
1.) Will my immoboliser key be reset?
2.) Do i need to completely remove both NEG and POS leads off the battery or can i just leave NEG off?

Thanks for help

23rd December 2008, 22:07

23rd December 2008, 22:48

Immobilizer will not need to be reset

Take the cables off both battery terminals

23rd December 2008, 23:24

Thanks for the reply.

23rd December 2008, 23:46

what's the benefits off resering the ECU?

24th December 2008, 09:41

Quote:

Originally Posted by jdizzy

what's the benefits off resering the ECU?

resets clock and sensors.
Can and has been proven by personal use to get rid of rough idling and flat spots in my case.

As a note.
I always leave the car to idle for a good few minutes, then take it for a sensible 15minute drive for all the sensors etc and ecu to find its settings.

24th December 2008, 09:51

How long do you have to leave it DC'd for to the ECU to reset.

24th December 2008, 09:58

I leave it off all night, im going to disconnect mine tonight tbh as its a tad dodgy

, does anybody leave it disconnected for the same amount of time ??

24th December 2008, 10:14

I dont want to leave mine over night without the alarm tbh. Would rather leave it DC'd whilst im working on other stuff in the garage. Just a bit paranoid when it comes to my baby!.

24th December 2008, 10:24

Quote:

Originally Posted by Ste

How long do you have to leave it DC'd for to the ECU to reset.

i always left mine around an hour, people say 30minutes but doesnt seem long enough to me.
Usually fitting gearboxes etc when i re set mine.

24th December 2008, 10:35

I've left my battery disconnected for 24 hours and it made no impact on the ECU. I was with a mechanic who had one of those very fancy ECU machines which allow them access to a vast majority of makes and models, and he reset my ECU (I've had my ECU mapped by Wayne Chipwizards, so bare this in mind) and when we started the ignition, the car chocked and spluttered, and it reeked of petrol, but after about a minute of idling, it was all back to normal.

24th December 2008, 13:30

Hey, this may sound a bit daft. But i can't seem to undo my battery leads. I'll post an image below. I've tried twisting them... pretty hard and they seem like they're welded! lol

If anyone has the same kind of "powerpak", how did you remove yours?

24th December 2008, 13:50

Do they not twist off if you get me lol, (anticlockwise iirc)

24th December 2008, 15:01

If theyre really tight you need to get a big pair of grips on those mate, and twist anti-clockwise

24th December 2008, 16:52

Don't worry, got it off in the end XD Got a hammer and screwdriver at it

So now ECU has reset (reeked of petrol and didn't take a second to get going. While battery was off, cleaned out Air Induct kit (Does anyone know the company with a logo of 'P'?) and installed a new rocker cam oil seal.
Drove around for 15mins or so and now one happy chap

Thanks for all your help

28th December 2008, 21:30

its been proven that if you disconnect your battery for about a hour and then refit the battery then go out and drive the car fast the ecu will change the parameters to your driving style and can make it a little more responsive, if other mods are done maybe a little more can be gained.

28th December 2008, 22:18

definately true about only half hour and no probs after as had ecu light come on fixed the sensor and reconected and it cleared it

28th December 2008, 23:17

ive got a clifford alarm... its unlikely for this to be affected when i disconnect the battery for half hour right?

also would engine degreaser be ok for cleaning a sensor

lol?

29th December 2008, 20:35

the degreaser should be fine just make sure its dried well but it would depend on what sensor it was.

8th June 2009, 13:12

is there any problems that can occur when resetting the ECU? i had a fiesta before and i reset the ecu as i was having some problems, and the car never drove right again. had to scrap it in the end.

i have just fitted a K&N induction kit and i have read that if you reset the ecu after installation the car can then re-configure itself to the new device. so wanted to do it, but was just wondering whether it could cause any damage as i had on the fezzy?

also, i the induction kit i had on the fiesta was mega loud (it was a pipercross). but since putting the K&N on my saxo i havent really noticed much difference in power or sound... any ideas?

Also, are there any sensors that have to fit into the kit? coz on the fiesta it has an Air sensor that slotted into the housing of the filter, but all i have found for the saxo is vreather pipes, which arnt long enough to fit in.

any help would be greatly appreciated.

20th November 2009, 04:29

i have got a vtr and i have a pipercross full induction kit on it and that has 2 pipes one to oil and one to the air injectors and its great i have had no trouble just need to clean it inside once every 6 month but runs perfect.

3rd April 2016, 16:00

When you disconnect the battery, remember that your central locking system will not work, so you have to manually check and lock the doors. Do not leave your car open over night

3rd April 2016, 16:26

Wow, 7 years later you post that? Random.