Changed battery, now odd starting problems

[mark pruett]

So I finally had to change my battery in my pickup (2005 Dodge Dakota, 3.7L V6, auto transmission). Through some quirk of manufacturing, this particular battery lasted six years, rather than the usual 3 or so that they seem to last here in Texas. For the past few months it had been starting harder than usual, but I figured it was just the battery getting old.

I took the old battery in, got it tested, it was definitely bad, and got a new one at Autozone. A Durastart Platinum EFB, size 65, if that makes a difference.

I installed the new battery, and now it doesn't want to start unless I give it a bump of the gas pedal. It turns over just fine- the battery is definitely good. But it's acting like it's not getting gas or air- when I give it a tap of the gas pedal, it starts right up and stays running. It idles a bit rough from time to time, but that's getting better as the ECU relearns it settings (or so I surmise).

What could be the issue here? I'm at a loss for what would be fine for starting with a mostly dead battery, and then NOT work with a brand new one with a lot more oomph.

 

[circuitsmith]

I suggest you clean the throttle body and IACV, if it has one.
When you changed the battery the ECU reset the idle parameters (among other things).

 

[Rand]

I dont know your specific application but generally it has to relearn all the idle parameters etc. might be something sticking or crudded up that it was compensating for previously.

 

[henni]

This is why we always use an OBD2 connector powering the computer when swapping batteries

 

[PimTac]

All your settings were erased. Get the truck started and run it for a while so the computer can relearn.

 

[MNgopher]

As noted by others, you likely lost the preset conditions the computer had learned over time...

Check your manual - there may be an idle relearn proceedure... As I recall my vehicles typically were let it idle for a few minutes, then let it idle with the A/C on max for a few minutes more. Otherwise it will just take it a while to get better.

 

[mark pruett]

Sure enough, that did the trick. I let it idle for a while, and drove it around on all the errands for the past few days, and it's starting up just fine without needing to touch the gas pedal now.