Idle problem with new battery

My battery just died yesterday when leaving work. I got the car jump started and drove thru stop and go traffic for an hour and stop at a NTB store where they checked the battery and verified it was dead. They replaced the battery and after some pounding on wrenches to get the positive terminal off they had it finished. They came in and asked if the engine ran that slow and did it always stall in gear. I told them it never had that problem and that it was running fine. They went and hooked up a meter to the battery and told me that the alternator was bad and that is what caused the dead battery. I told them if the alternator was bad and the battery dead then how did I drive it that far with the drl's on and the AC running. They kept repeating the same thing over about the bad alternator and that caused the dead battery.

 

When I got home my dad and his neighbor came over and brought a meter. They tested the battery and alternator and it was reading 14volts.

 

The car keeps throwing the code P0506 Idle Control System RPM Low. The engine seems to idle at 100-200 rpm and after sometime it will idle between 500-750prms. It idles so low that when you come to a stop the engine sometimes dies. The car also seems to hesitate when you give it some gas.

 

I don't know if they shorted out the positive connection from pound on the wrench or if they hit something. But they sure wanted to sell me an alternator.

 

Does anyone know or come across what could be wrong?

I can't see an alternator being bad if it is putting out 14 volts. Now if it was in excess of 16, then that is bad.

I have an update. I stopped by advanced auto parts and told them what happened and they did a full array of test on the alternator and battery and everything came back good. While I was there I bought some card cleaner. When I got home I took apart the the intake piping from the air filter to the throttle body. When I sprayed into the throttle body the cleaner came out black. I open the butterfly and put a finger in along the top and it came out black. I took the throttle body completely off and cleaned everything. I put everything back together and now it is running smooth. It still is acting weird when you slow down i can see the tach going up and down.

 

I just don't know how changing the battery would cause the idle problem unless they shorted the positive and it zapped one of the sensors.

Carb cleaner can destroy the lining in the throttle body.

Carb cleaner can destroy the lining in the throttle body.

+1

You may need to clean/replace the Idle Air Control valve. I had similar symptoms and found that the valve movement was pretty stiff. Dousing it with WD-40, especially under the flange on the shaft made it move pore freely. When I reinstalled the valve, the idle was normal and the RPMs didn't hunt around any more.

If the + terminal was so corroded they had to wrench it off..... was it properly cleaned before being put back on?

Everything is working properly now. After cleaning the throttle body the started to idle a lot better. I went from 22.2 to 26.4 mpg on the gauge.

 

OhBe1 I also noticed I was low on blinker fluid so I filled that up also