Hey everyone, curious about what went on with my car when I moved it out of the garage. It's been sitting for a while with the battery disconnected, car has not moved for about a month, anyways I reconnected the battery, started it and got a slow start and a low idle/surge.

I decided to drive it around my neighborhood a few times to get it warmed up to see if it got any better, ran normal under throttle but the RPM's dropped low and surged at idle. As soon as I pulled into my garage spot it would not start again, all I got was a *click*.

I believe it may need a battery, but wondering if this sounds like anything else to anyone? Alternator possibly?

Any opinions would be appreciated

 

if the car is stored over winter, sits for somewhat long periods in storage & not driven a lot and you don't have a battery float charger on it,
then i wouldn't do anything before

charging the battery properly at least overnight to get it back to or near 100% state of charge

or put a new battery in it, that has been fully charged. a new battery off the shelf isn't necessarily at 100%.

put a digital voltmeter across battery terminals, if you have below ~12.2 volts then it's basically dead and needs a charge. if measuring voltage across battery while engine running doesn't show higher than 13.0 volts then it may be an alternator problem- assuming the battery is good.

 

You're likely looking at a couple different issues here.

If the battery was disconnected, then you may have some minor idle weirdness until the PCM relearns the idle conditions. Some of these cars seem to be more affected by this than others (half of mine have been, even when stock.) There is an idle relearn procedure you can do to speed the process, otherwise it will eventually relearn on its own. Some surging and/or low idle moments are normal for the first little bit if you don't do the relearn.

Secondly, it sounds like you have a weak battery. If it was fully charged prior to being disconnected, then it shouldn't be seriously low on power just four weeks later. I have considerable experience with this as I've been storing cars for a long time and regularly watch/maintain the batteries. My '98 sits with the battery connected all winter, I hook up a smart charger every 3-4 weeks and let it charge to completion. I just did this on Friday, and the battery was still at 12.34 volts after sitting, connected, in a cold garage for three weeks untouched. This is more than enough voltage to get the engine started (in fact it will start even below 12.2 volts), but cranking will be a bit slow. If yours was disconnected, it should have held much better voltage than mine after just four weeks. For example, I disconnected the battery on my '71 back in mid-October and by mid-January the voltage had only dropped to 12.5 volts. A healthy battery that's been fully charged will hold strong voltage for much more than 4 weeks when not connected to a car.

So, as mentioned above, you'll want to make sure the charging system was working properly and left the battery with a good charge prior to storage. You can verify this using a multi-meter with the engine running as described above. If you're getting proper voltage with the engine running then the battery probably just isn't holding the charge, therefore time for a new battery.

 

Thanks for the fast replies guys, I appreciate it. This battery is an ACDelco from 2010 so I do think this could be the culprit, especially since this car has sat a lot over this time period. Along with the PCM relearning from me disconnecting the battery which is probably what probably caused the funky idle, I had forgotten these cars do that sometimes. I have to move it out of the garage later this week again (having work done on the door, not my choice) so I'll test it with a multi-meter then and I think my problem will become clear.

Thanks again guys.