Chuggle Surge Or Shudder At 38-45 MPH - keywords 1 afm active chuggle drone exhaust fuel management moan shudder surge

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Some customers may comment about a slight chuggle, surge or shudder type condition that occurs when the vehicle is in ovedrive and traveling at a steady speed in the 38-45 mph range. The condition is most obvious when a very light throttle is applied. The very lightly applied throttle is not enough to cause a releasing of the torque converter clutch or a transmission downshift.

Set the Driver's Information Center (DIC) so that it displays the Instant Fuel Economy and Active Fuel Management™ Indicator. Drive the vehicle as described above while observing the Active Fuel Management Indicator. When the condition occurs you should observe that the vehicle is operating in the 3 cylinder mode and is not switching to the 6 cylinder mode when the very light throttle is applied.

The Manifold Absolute Pressure (MAP) Sensor may not be interpreting the engine vacuum signal correctly. If this is found, replace the MAP sensor.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.