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 Description of  Calibration AYBKG

Calibration description for AYBKG.  Version 5.

The calibration generally increases torque and horsepower by 10 respectively. It also reduces power fadeout associated with engine compartment heat. The engine will be more powerful and the output will be more consistent as the engine thoroughly warms up.

The original equipment calibration is designed to protect the engine when 87 octane regular grade fuel is used. This calibration optimizes the knock control for fuel with 91 octane or more. Premium grade fuel is required.

- The ignition spark advance is increased 10% at all engine speeds. As a result, the advance at wide open throttle is increased by 3 over the stock calibration to 28 degrees.

- Both of the cooling fans are turned on at 205 degrees. Both are turned off at 200 degrees.

- The fuel delivery at wide open throttle is about 6% rich in the stock calibration. The fueling is reduced by 3%.

- The stock calibration retards the ignition spark advance when the intake air temperature is over 90 degrees F. This is revised to 160 degrees and the amount of retard is decreased.

- The engine control system tends to sense false ignition spark knocks during fast throttle openings at lower engine speeds. This can result in a 10 hp power reduction for about a second after the throttle transition. To address this, the ignition spark timing knock retard is reduced by 50%.

- The CAGS (1 to 4 shift) is disabled. Also, the 1 to 4 shift lamp is turned off.

$275 + $8 shipping in the USA. The cost is $225 if a calibration package is sent to us for an exchange.

To purchase, refer to the bottom of our Home Page by clicking Here.

The calibration can be customized for specific requirements. For customization details click here.

The performance calibration AYBKG is based on GM's latest release of the calibration for '90 LT5 engines. GM calibration AYBK was released as a service part via Product Service Bulletin 476503, dated February, 1994. It was released to address problems with idle fluctuation after a hot restart, increase in idle speed after a hot restart and excessive engine speed during coast down to a stop with the clutch disengaged.

The factory installed '90 calibration controls the Up-Shift lamp on the cluster. I don't know why, but GM disabled the up-shift lamp on the Service Part calibration AYBK. Because of that, AYBKG does not use the up-shift lamp. The feature can be reactivated to flash the light at any specified engine speed up to 6400 rpm. This feature can be added for $50. There is no additional cost to add it to a customized calibration.

Installation procedure. Refer to pages 26 through 29 of the Calibration Presentation. It is very important to disconnect the power to the ECM for 10 seconds after installing a new calibration chip. As an alternative to the procedure in the Presentation, the negative battery cable can be removed for 10 seconds.