Low idle after battery removed/replaced.

**Linz** · 09-07-2009, 04:07 AM

Hey all, had to change the drivers side headlight bulb last night so had to remove/replace the battery so I could get to the thing (big hands).
Anywhooo, when driving it today, when you put it into reverse or drive, the idle speed drops right down to almost stall speed and then picks up again. The car has been driven about 40 kms since the battery was out but it still has the low idle after changing gears. I've done the disconnect battery thing heaps of times in different Falcons (AU, BA's etc.) with no problems like this afterwards

: ...anyone have some clues as to what is wrong??
Thanks in advance...Linz.

crakrz · 09-07-2009, 05:58 AM

Pretty normal, give it a few days for the ecu to re-learn. Or to speed the process up a bit, let it sit there idling in park for about 10mins, the idle should improve as time passes, as the ecu is relearning. Then put it in drive with your foot on the brake and sit there for 10mins again. This works for me, see if it works for you.

whiskers · 09-07-2009, 09:22 AM

or you could try this to "re learn the ecu" it's quicker

http://www.aufalcon.com/cgi-bin/inde...f=techdocs/ECU

bodes-sh · 09-07-2009, 10:01 AM

might be worth cleaning out the throttle body and isc too if you haven't recently. seems to help a bit

**Linz** · 09-07-2009, 12:12 PM

Thanks a lot guys...I'll give it a go

:

gtfpv · 10-07-2009, 05:25 PM

was the car tuned in the past ?

The Monty · 10-07-2009, 05:33 PM

Just drive it around for a day or two, it will be fine. Its just that the ECU has reset. Nothing wrong with it, just give it time.

GK · 10-07-2009, 05:44 PM

Quote:

Originally Posted by linz

Did this last night but still no good. I'm just wondering if the battery may be on it's last legs, getting it checked out this afternoon.

Did the battery check out okay, or was it cactus?

GK

mik · 10-07-2009, 09:55 PM

i`ve disconnected my battery a few times now to do variouse jobs and it seems to run exactly the same after reconnected, am i just lucky? are the battery posts/terminals clean?

Dave_Obsession · 10-07-2009, 10:28 PM

Quote:

Originally Posted by mik

i`ve disconnected my battery a few times now to do variouse jobs and it seems to run exactly the same after reconnected, am i just lucky? are the battery posts/terminals clean?

Depends on how long the battery is disconnected for - give it about 45 mins to an hour....then the ECU has definately reset itself.......

I did the same thing a while ago - took a couple of days driving (about 100kms) and everything was fine after...........felt like it had a little more grunt as well!!!

Probably should do it again soon I reckon!

**Linz** · 11-07-2009, 09:30 AM

Quote:

Originally Posted by whiskers

or you could try this to "re learn the ecu" it's quicker

http://www.aufalcon.com/cgi-bin/inde...f=techdocs/ECU

Did this last night but still no good. I'm just wondering if the battery may be on it's last legs, getting it checked out this afternoon.

**Stav** · 11-07-2009, 10:25 AM

Quote:

Originally Posted by linz

Hey all, had to change the drivers side headlight bulb last night so had to remove/replace the battery so I could get to the thing (big hands).
Anywhooo, when driving it today, when you put it into reverse or drive, the idle speed drops right down to almost stall speed and then picks up again. The car has been driven about 40 kms since the battery was out but it still has the low idle after changing gears. I've done the disconnect battery thing heaps of times in different Falcons (AU, BA's etc.) with no problems like this afterwards

: ...anyone have some clues as to what is wrong??
Thanks in advance...Linz.

Yes the ecu has many startup maps which tend to go rich on battery reset and the idle speed is also altered.This is due to the fact that the ecu has adjusted over time to wear and tear in the cars engine to keep it good.Unfortunately it does not hold the memory on battery reset and starts from base maps hence the problems.Id recomend resetting it a few times until it finally comes good.Then do not reset it again

**Linz** · 11-07-2009, 06:42 PM

Thanks again for the replies everyone...battery tested up fine, the car is gradually getting a bit better, it's ok with no a/c running but as soon as you turn it back on, it starts stalling or very low idle so we'll just keep driving it over the next few days until it comes good. Don't know whether it's BS or not, but Southside Fraud service guy reckons the ISC is a bit of a problem sometimes on the AU's after battery disconnection...time will tell.
It's strange that this should happen as I've disconnected batteries lots of times without a backup power source on EB's, EF's, EL's, AU's and BA's without the hint of a problem...I guess there's a first time for everything.
P.S. Guess what I bought today? Yes, that's right...a backup power supply :hihi:

lofty · 11-07-2009, 07:30 PM

Quote:

Originally Posted by linz

P.S. Guess what I bought today? Yes, that's right...a backup power supply :hihi:

Please show & tell. I'm scared to disconnect my batt to fit cruise cos so many ppl have problems.

**Linz** · 11-07-2009, 10:49 PM

Quote:

Originally Posted by lofty

Please show & tell. I'm scared to disconnect my batt to fit cruise cos so many ppl have problems.

It's a very simple thing that I got from Autobarn...a cigarette lighter plug with a couple of leads attached and a 9v battery connector on the end. Clip on a new 9v battery and fit it into the power source socket and it's SUPPOSED to hold memory. Not sure for how long, but it'd be good enough to change the likes of headlight bulbs or fit a new car battery.