Idle speed adjustments have not existed since the late 1980's. It is computer-controlled based on various sensor data and operating conditions. Some throttle bodies do indeed have adjustment screws that are hard to get to, but they are only for setting the starting point. When people monkey with them, the computer is unable to adjust idle speed properly and surging or "hunting" can result. That can drive people nuts trying to figure out the elusive cause of erratic idle speed.
Low idle speed is real common on Chrysler products after disconnecting the battery. It can occur on other brands too, but typically it takes care of itself. My strong recommendation is to not mess with anything in an attempt to solve the concern as you will just be inserting a whole bunch of new variables, and none of them will fix the idle speed. No mechanical problem developed from disconnecting the battery.
Disconnecting the battery caused the engine computer to lose its memory, just like happened to the station presets and clock on your radio. Professionals usually use a "memory saver" which is a fancy name for a small temporary battery connected to keep the memories alive while the battery is being replaced. Failure to use one on some newer imports can have really catastrophic results. The computers on some VW's, for example, can lock up and can only be unlocked with a tow to the dealer, often for a cost of over $900.00.
In your case, it sounds like your computer still needs to relearn what Chrysler calls, "minimum throttle". All the other fuel trim numbers and sensor characteristics will be relearned as soon as you start the engine, but minimum throttle can require a very specific set of conditions to initiate the relearn. On Chrysler's, this is real complicated so I hope you are sitting down. Drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
Until that is done, the computer will not know when it has to be in control of idle speed. The engine may not start unless the accelerator pedal is held don 1/4". You will not get the nice idle flare-up to 1500 rpm at start-up, and it will tend to stall at stop signs.
I rarely read about the need for the driver to manually force the relearn by performing certain steps while driving for other car brands, so whatever is required is usually easily met. You might ask a mechanic at the dealership if there are conditions you have to meet. One other thing to keep in mind is it is real common for multiple fuses to blow when reconnecting a battery or when connecting jumper cables. That is from the current surges when the numerous computer memories are charging up. Do not overlook a blown fuse inside and under the hood, but those usually involve additional symptoms or dead circuits. Look for anything else that is not working since the battery was replaced.
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Friday, December 15th, 2017 AT 12:51 PM
