Saving memory when disconnecting battery?

86GTRag · May 12, 2007

I hadn't driven my 86 in about a year. It is still SD. I put a new battery in and have been driving it for a few weeks now and the more I've driven it the better it runs,at idle cruise and WOT. I guess the computers' memory is fine tuning the car as I drive.
Can you connect a 9V battery to the terminals when unhooking the battery to save the computers' memory? I'd hate to have to start all over again and make the car "relearn" everything.

stang&2Birds · May 12, 2007

That should work if you use a NEW 9V battery and do NOT turn the key on.

Fett · May 12, 2007

I have never tried it, but I don't think it will work. The entire electrical system is based on a 12v charge, I don't think a 9v will do anything. I could be wrong....I just don't see that working. Also, for how long are you talking? If you are talking about just changing a battery, then do it quickly. If you can reconnect power to the electrical system within a matter of seconds, then the memory should stay alive. I know that in the past (different car) I changed the battery out quickly and never experienced the typical "relearing curve" that I would normally get when disconnecting the battery for an extended period of time.

HISSIN50 · May 12, 2007

I used to do it and it worked fine for me. I did this for radio presets (I'm kinda old and it takes me an hour to reprogram what a 5 year old can do in 30 seconds).

For the KAM, the puter's capacitors should stay alive for a bit after you disconnect the battery (if it's going to be a quick disconnect).

Otherwise, I suppose you could use a quick-disconnect terminal. Some allow you to connect a circuit which circumvents the cut-off (for alarms, etc). You could add a power leg to the KAM from here (Leave the OEM wiring intact and simply add an aux power source. I see no issues with doing this. If someone does, speak up).

Good luck.

stang&2Birds · May 13, 2007

Fett said:
I have never tried it, but I don't think it will work. The entire electrical system is based on a 12v charge, I don't think a 9v will do anything. I could be wrong....I just don't see that working. Also, for how long are you talking? If you are talking about just changing a battery, then do it quickly. If you can reconnect power to the electrical system within a matter of seconds, then the memory should stay alive. I know that in the past (different car) I changed the battery out quickly and never experienced the typical "relearing curve" that I would normally get when disconnecting the battery for an extended period of time.

It works because the EEC and most Radios use 5V internally. All they need is ~9V to power the *non volatile memory* (KAM in the EEC).

BigDanTheMan · May 13, 2007

it takes a good 10 minutes at least for the memory to clear. i don't know much about speed density, but mt beat up pony with MAF goes from stalling once after re-connecting the battery to running like a champ within two minutes.

the poor performance you might have been experiencing after firing up your pony for the first time in a year might been more related to it sitting for a year than the EEC.

TomCat · May 13, 2007

http://www.easycarcovers.com/Computer-Memory-Saver.html
We used to sell a similar product at CSK, but I think it's been pulled from the shelves. Makes it nice and clean, though.

HISSIN50 · May 13, 2007

Tomcat's version look like what I use (I just made mine from 2 bucks worth of parts though. It's not as pretty but works fine).

I had to make a similar rig to power up my MAFtuner when uploading files (while at my PC). I think that one cost me 3 bucks because I needed a pair of goofy terminals.

Just alternatives if folks are poor like me.

vristang · May 13, 2007

TomCat said:
http://www.easycarcovers.com/Computer-Memory-Saver.html

That is sweet

With all the times I work on my car, I will be making something like this fairly soon...

:Word:

Fett · May 13, 2007

Interesting, I didn't think a 9v would work. I have a Tweecer and don't have to worry about it....but I have a friend who just got his car running again and needs to relocate his battery, so I will pass this info along.b

Fett · May 13, 2007

Actually, this brings up a question. I mentioned I have a Tweecer and don't have this problem. Since I put my Tweecer in, I have been able to remove my battery for hours and never had any issues. The more I think about it, I don't remember having to re-load my tune back into the Tweecer after the battery disconnect....but I might have.

Can the Tweecer hold it's tune with the battery disconnected? The last time I had my battery out, it was out pretty much the whole day. I reconnected it and the car idled and ran perfectly. Like I said, I don't remember having to reload my tune, I think it was still loaded in the Tweecer.

vristang · May 13, 2007

Fett said:
Can the Tweecer hold it's tune with the battery disconnected? The last time I had my battery out, it was out pretty much the whole day. I reconnected it and the car idled and ran perfectly. Like I said, I don't remember having to reload my tune, I think it was still loaded in the Tweecer.

The .bin or .ccf file is in the tweecer J3 module. This file is not lost, and you can pull the tweecer from the ecu for months and it will still be there.

If your tune has been dialed in well enough so that your KAMRF's don't reflect any change (close to 1.00), then you wouldn't see much difference by disconnecting the battery and losing the KAM.

In my datalogging the soonest I saw any adjustment of the KAMRF's was about 5 to 10 minutes of driving.
This is using the stock X3Z Adaptive Table. With some modification of the table I was able to get the adaptive to be nearly complete in 20 minutes. (this was with an injector issue and a C&L MAF, both of which preventing any accuracy in my tune)

No way the adaptive is complete in 2 minutes. I would say there is a cold start issue there. Might be worth looking into?

jason

Fett · May 13, 2007

I don't have all that "aggressive" of a tune, just basics. But prior to the Tweecer if I disconnected the battery for an extended period of time, I would get the typical issues. Wouldn't idle smoothly, surged, and chugged while driving in low RPMs. That would last for a day or so then begin to smooth out. Since the Tweecer install, after reinstalling the battery, the car would start up and idle perfectly...just as if I never disconnected the battery. I always just assumed the loaded calibration was enough to circumvent any "learning" issues.

vristang · May 13, 2007

It doesn't take a very 'aggressive' tune to get the KAMRF's near 1.00.
MAF Transfer and injector slopes can do a lot...

Odds are, your still utilizing the Adaptive Strategy, but it isn't very noticeable when only minor adaptations/corrections are needed.

jason

Is this a good candidate for the Tech Thread Index?

Shakerhood · May 14, 2007

TomCat said:
http://www.easycarcovers.com/Computer-Memory-Saver.html
We used to sell a similar product at CSK, but I think it's been pulled from the shelves. Makes it nice and clean, though.

I have one of those sitting around somewhere, I just have not looked for it or could not find it when I was about to unhook my Battery.

4G-KDMP · May 14, 2007

TomCat said:
http://www.easycarcovers.com/Computer-Memory-Saver.html

those work fantastic.

Saving memory when disconnecting battery?

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