Will changing the VIN stored in the PCM bypass "VIN locked" programs? more ››
What are bi-directional controls?
Bidirectional controls are a set of commands that can be sent to the PCM to cause it to perform ad-hoc tasks under the command of the Scan Tool. Bidirectional commands bypass the PCM’s factory settings and force the PCM to operate in a particular way.
The most common uses for bidirectional controls are:
Performing a CASE (Crank Angle Sensor Error) learn.
Performing a cylinder balance test
Temporarily altering the idle speed to determine the effect of different idle speeds
Switching transmission solenoids off/on for diagnosing faults
Engaging/disengaging the TCC.
Enabling/Disabling learning.
Altering spark advance.
Altering command AFR.
Why are bi-directional controls temporary?
GM built in safeguards to prevent bidirectional controls from corrupting or permanently altering the programmed calibrations. One such safeguard is that the PCM requires the scan tool to send a "keep alive" message to the PCM every 5 seconds. If the next "keep alive" message is not received within 5 seconds of the previous one, then the PCM automatically terminates ALL bidirectional control settings and returns control to the programmed calibrations.
That means whenever EFILive is unplugged or the vehicle's ignition is switched off, the PCM will always return to it's programmed calibrations.
Do any of EFILive's changes remain in the PCM once disconnected?
Yes. There are a number of changes that the Scan Tool can make to the PCM that are either permanent or residual.
Clear/Reset diagnostic trouble codes is residual.
Clear learned long term fuel trims is residual.
Changing the vehicle's VIN is permanent.
Crank position sensor relearn is permanent.
Can I override two or more controls at the same time?
Yes
Can overrides be used at the track or strip?
Depending on the number of overrides, the update frequency is between 5-10 times per second, which is not fast enough for racetrack or drag strip use. The spark and fuel settings would lag actual conditions by up to 1/2 a second.
The Spark and fuel maps are designed for altering only one or two parameters under the controlled conditions of a dynamometer - not for a 10 second blast down the 1/4 mile.
While it could be done, we do not recommend it nor do we believe it would be effective.
Can I change the VIN stored in the PCM?
Yes, use the menu option Bidirectional->Change VIN.
Will changing the VIN stored in the PCM bypass "VIN locked" programs?
