Hi Everyone!

Can a super weak battery cause the engine to stall as soon as it starts?

Well mine does, and the weaker its getting the more often its doing it. However the next turn of key seems to be ok.

Im just surprised how the car even manages to start with such a slow and weak starter action.

i think i may be that its supplying enough powee to the starter to crank it over but the coil is not recieving enough to create a spark.... just a guess, but a weak battery should be continous and shouldn't start perfect next time over... have u tested the battery with a multimeter to confirm that it is weak? my dads TE use to do the same thing till we determined the coil was stuffed

This was covered several times. Check all the fuses under the driver footwell and make sure everything is ok. Also, I had the same issue with my TH years ago, and I bought a new battery which fixed the problem for me.

First start, ran for about a second, then I heard a click under behind the console, and car stalls, then start engine again, and it remains running... new battery fixed it for me.

Yeah i hear a click too before it stalls.. The battery was good while the car was in regular use but its been in the car for more than its suggested life.. a few days ago i left the car in the garage for about a week and since then the battery has become weak. The changeover is definitely due but the way the car stalls kinda worried me abit so I was just making sure nothing else has decided to die in the meanwhile.

The reference voltage post start up us falling below what the relay needs to stay active, the click is the relay switching power to the ecu off thus the stall. Many efi cars will behave this way. Later e series falcons will crank all day but not even fire

These cars must have some awesome relay or something. It picks up even on the deadest of the dead battery at times!

These cars must have some awesome relay or something. It picks up even on the deadest of the dead battery at times!
Because the engine relay is controlled by the ECU which runs on 5V rather than 12V, it has a 5V drive circuit. The ECU gets 5V from 12V via a voltage regulator, so even a quite sick battery has enough to drive the ECU and therefore the relay.

Correct but not how it works unfortunately, a sick battery will have a voltage drop after the crank cycle and thus drops the relay, this is a very common issue with many cars, with ford for example if the voltage is below about 12.4v or something like that (would need to look it up) it will not even try and fire. We often get 380's in here from the auctions where they will crank all day but will not fire, put on a jumper pack to give them a little boost and start straight off the key

Correct but not how it works unfortunately, a sick battery will have a voltage drop after the crank cycle and thus drops the relay, this is a very common issue with many cars, with ford for example if the voltage is below about 12.4v or something like that (would need to look it up) it will not even try and fire. We often get 380's in here from the auctions where they will crank all day but will not fire, put on a jumper pack to give them a little boost and start straight off the key

I was leaving a lot out, just to make the point that the ECU can function and is in control even when the battery is severely degraded and other things don't function well or at all...

It isn't hard to do the "check battery voltage before start" thing in ECU code, and it doesn't surprise me that more modern ECUs do this. That the 380 ECU permits cranking but won't supply fuel/spark as you mention seems odd though, almost as though the minimum voltage during cranking to enable fuel/spark was set slightly too pessimistically... perhaps something not addressed during development testing.

I got a new battery today so one thing is sorted. However once the new battery was connected, the car kept stalling straight away. The battery guy said I have to keep the engine running for about 15 to 20 mins before the ECU gets retuned. So I took the car straight to the freeway and drove for about 20 mins. Now it seems to start nice and perfect but when the car was started a few hours later and the engine had cooled down, the RPMs kept dropping to pretty much zero until the car came to the normal running temperature. Any remedy for this? maybe I need to unplug the battery and do it all again with a parked car under some acceleration? whats the best way around this?

After a battery disconnection, your idle speed control (ISC) settings are lost as are the fuel trims. To re-establish the ISC settings (and the idle fuel trim), the quickest way is simply to start the engine and let it idle - at least 12-15 minutes if the engine is cold, at least 7-10 minutes if the engine is warm. The ECU will eventually re-establish the settings even if you don't do this, but it will take much longer.

The ECU seems to have finally worked it out on the 3rd reset

Just put a new battery in mine after experiencing the "start then stall, then start then OK" symptom for a while - thanks everyone for the advice re: the battery -

I put a Century higher spec battery (http://www.centurybatteries.com.au/search/index.php/batteries/ID-49-1373) in which I got for $165 from SC Auto. Car seems to have a bit more go as well (to me anyway). Didn't have any probs with idling although trip computer was blank (ie dashes) for about 10 mins of driving).

its supposed to take all that time before it fully comes to its senses :)

it might seem unlikely, but if your coolant temperature sensor has failed, the car will not start easy until its warm. Especially on a really cold day.

Without the coolant temp sensor connected, i had to pump the throttle gently (with EFI) just to stop it stalling. After about 10 seconds, it would not stall by itself anymore.

@ 05-02-2013 10:42 PM #11
WytWun
thanks thats what i was looking for .