This is a common problem after the battery has been disconnected. The Engine Computer will relearn fuel trim and sensor data as soon as you start driving, without you even noticing. The one big exception is "minimum throttle". That requires a very specific set of conditions to initiate the relearn. Until that is done, the engine will idle too slow. It may not start unless you hold the accelerator pedal down 1/4". It will tend to stall at stop signs, and you won't get the nice "idle flare-up" to 1500 rpm at start-up.
To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.
The computer needs to see high intake manifold vacuum to know your foot is off the accelerator pedal, and it needs to see that for seven seconds to know you're not holding the pedal steady with your foot. Once it knows that, it takes a voltage reading from the throttle position sensor and puts that in memory. From then on, any time it sees that voltage, it knows it has to be in control of idle speed.
Any movement of the accelerator pedal, or a tap on the brake pedal will abort the relearn. If this procedure doesn't work, do it again while holding the brake pedal up with your foot. In rare instances driving on bumpy roads can cause the brake pedal to bounce and turn on one part of an improperly adjusted brake light switch.
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Friday, July 22nd, 2022 AT 3:09 PM
