Car Breaking Up After Sitting For 10 Days

[savattguy]

So I went out of town for about 8 days and when I got back my battery was completely dead, long story short we eventually got into the car. When I finally got to start the car up it was idling rough right off the bat, sounded like it was misfiring at idle. I went to drive the car and when I would give it WOT it was completely breaking up (stuttering, cutting power, misfiring, etc.). After about maybe 30 minutes of running we went to drive the car again and it was totally fine, not misfiring, breaking up, or idling weird. Its been like a day since this happened and the car is totally fine still. I was thinking maybe it was just because of how dead the battery was, maybe it wasn't at the right voltage and that may have been what have caused it. Also I have the 2JR cowl intake and I was thinking possibly water got into the intake which caused it go get into the fuel? The car only has 26000 miles so I was thinking it wouldnt be spark plugs. If anyone has some insight I would appreciate it greatly.

 

[powermatt]

Low voltage can cause all sorts of weird ignition problems, and bad sensor readings. Combined with the ECU trying to re-learn the various non-persistent values, that could definitely explain why it wasn't running well.

 

[TyphoonFiST]

Test the battery * thats where I would start!

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[SteveS]

Probably like what would happen with my wife's Scion tC every time you disconnected the battery to change it or do work on the car. It would take 15-20 minutes of driving and several on/off engine cycles for the ecu to relearn things and settle everything down. Until then it would die at idle, idle erratically, stumble on acceleration.

 

[Philld_with_donuts]

I've had this happen as well. Happens after I have the car sitting for awhile, or unhook the battery immediately after shutting the car down.

I've assumed it has to do with the ECU memory being cleared, as well as slightly fouled injectors needing to clear out. After a few short drives everything returns to normal and it runs great.
I wouldn't lose any sleep over it.