Adamthepizzaguy

Jeeps been sitting with a dead battery for a few weeks. Now when I go to start it i have to use the throttle pedal to idle it at first then after i rev it a little bit it holds clean idle at 900 rpm. What's the likely cause of this?

97grand4.0

sticky idle air controller

Garrett S.

I think they just do that until the battery is charged up or they relearn or something. I have had 3 different ones that have done that when the battery goes dead. It usually clears up after a while.

Jeepwalker

Have you driven it much since then, or only started it a couple times? Leaving a vehicle with a totally drained battery for a period can allow the slow-drain (memory) capacitors in the ECM to also drain. Then when the vehicle is re-started it needs to run a bit and "re-learn". It'll usually stumble a little but smooth out more and more in 10-15 minutes.

But if you've been driving it, that's probably NOT the reason. Could be a number of things. I've had rodents move in when a car sits and chew through vacuum hoses, wires can become corroded (connections may need wiggling), You could have an injector leaking down. I'd do as suggested above and remove/clean the Idle Air Controller which is at the base of the throttle body. Remove the top rubber air intake and check your butterfly and throttle body for a build-up of gunk. Clean with carb cleaner and a soft brush if you notice any deposits., Sensor grounds can also go flaky when a vehicle sits. If you removed the battery, maybe check the connections ..just in case, and the engine /sensor grounds.

Did you look things over in the engine compartment CAREFULLY?

jordan96xj

Low voltage. If the battery has repeatedly been drained, it may need to be replaced. Once you get it idling, you can attempt to give it some time to see if charges back up successfully (or go on a nice long drive), though it is easier on the vehicle if you just find a charger and do it that way (slow charge, over night has the best chance of bringing the battery back to where it should be). Consider having the battery load tested at an auto parts store when you get the chance.

Jeepwalker

When a battery is competely dead, you may need to use a very small trickle charger on the "Maintain" setting to put like .6A in it for 15-30 min to get some juice in it to take a charge. Then you can go to 10A. Often completely dead batteries often won't take a charge ....and so-called "Smart Chargers" don't often recognize a completely flat battery and will indicate it's no good. But start with a small trickle and once you get it kick started, up the amps. Don't charge over 10A. Also, check the water if you can remove the cap/s. Add distilled water if needed.

I've had several completely flat batteries, including frozen batteries which I was able to bring back from the dead which lasted many years. In the summer, however, when a battery sits dead for a while the lead plates begin to coat with sulfide and that coating inhibits ion exchange ...basically a weaker battery. One or two times if recharged shortly afterwards won't cause a lot of permenant damage, but letting it sit dead a couple times, for a while can and probably will.

Also, it takes like 8-10 hours to fully re-charge a completely depleated battery. Just driving it down the street to the mini-mart for 3 cases of beer isn't going to charge it back up!!

BillyBoy

Dashboard solar panel. Kept mine alive for years of not driving. 20$.

Jeepwalker

Yes and no. The cheap solar panels 'could' overcharge your battery if they don't have a regulator to stop charging. Possibly boil off some water. I believe a solar charger shortened two of my batteries leaving it on full-time. Now I put it on periodically during the day and took it off at night. But maybe yours is 'smarter' than mine. Mine is a Harbor Freight (older version) solar charger. There's no way to know how full or empty the charge is either. It's just guesswork (with mine). But overall, they work great for things like tractors, machinery and other batteries which may not be near electricity.