just got back from a job in Winston Salem, about a hundred mile ride. the truck ran great except for two little issues. thought i'd see if anyone had ideas:

after coasting around a right hand turn, ie rolling a stop sign , or merging on a down hill cloverleaf, when i begin to accelerate again the truck stutters and stumbles. i've only noticed this on rights, not lefts. it's like it's starved for fuel or the computer can't decide which gear it wants. and yes, i had full tank.

the other coasting issue i noticed was after running 75-80 in a school zone, er, i mean on the freeway, when i back all the way off the throttle the whole truck kinda shimmies and shakes for several seconds. runs like butta at any part-throttle, and I don't notice it a lower speeds. didn't have the urge to try higher speeds. thoughts?

Rooster said:

just got back from a job in Winston Salem, about a hundred mile ride. the truck ran great except for two little issues. thought i'd see if anyone had ideas:

after coasting around a right hand turn, ie rolling a stop sign , or merging on a down hill cloverleaf, when i begin to accelerate again the truck stutters and stumbles. i've only noticed this on rights, not lefts. it's like it's starved for fuel or the computer can't decide which gear it wants. and yes, i had full tank.

the other coasting issue i noticed was after running 75-80 in a school zone, er, i mean on the freeway, when i back all the way off the throttle the whole truck kinda shimmies and shakes for several seconds. runs like butta at any part-throttle, and I don't notice it a lower speeds. didn't have the urge to try higher speeds. thoughts?

Click to expand...

Any chance its around 45-55 mph?

try this

TSB
08-21-11 4 WHEEL DRIVE/ALL WHEEL DRIVE - WITH CONTROL TRAC - SHUDDER ON ACCELERATION/DECELERATION OR BINDING ON SLOW TURNS

Publication Date: October 10, 2008

FORD: 1997-2008 Expedition, Explorer
2006-2008 F-150
2007-2008 Explorer Sport Trac
2008 F-150
LINCOLN: 1998-2008 Navigator
2003-2005 Aviator
MERCURY: 2005 Mountaineer
2006-2008 Mountaineer


ISSUE:
Various 1997-2008 vehicles equipped with either 4 wheel drive or all wheel drive and equipped with control trac may exhibit a shudder on acceleration/deceleration, binding in slow speed turns or noise from the front driveline and/or transfer case. The shudder/binding will occur with the vehicle being operated in the awd/auto 4x4 mode. The shudder/binding may be due to incorrect tire circumference or improper tire inflation pressures.

ACTION:
Follow the Service Procedure steps to correct the condition.

SERVICE PROCEDURE

NOTE: THIS DOES NOT APPLY TO 2006-2008 MOUNTAINEER WITH A 4.0L ENGINE OR 2007-2008 EXPLORER AND SPORT TRAC WITH 20 INCH WHEELS.



NOTE: VEHICLES ON THE LIST MAY REQUIRE REPLACEMENT OF TIRE/S IF THE TIRE CIRCUMFERENCE AVERAGE BETWEEN THE FRONT AND REAR AXLES ARE OUTSIDE OF THE 1/2 INCH SPECIFICATION OR IF THE TIRE CIRCUMFERENCE FROM SIDE TO SIDE ON EITHER AXLE EXCEEDS 1/2 INCH DIFFERENCE, THE SMALLER TIRE(S) MUST BE REPLACED.



NOTE: REVIEW THE WARRANTY AND POLICY MANUAL FOR FORD MOTOR COMPANY TIRE REPLACEMENT WARRANTY BEFORE PERFORMING THE SERVICE PROCEDURE.



NOTE: ONLY USE REPLACEMENT TIRE AND WHEEL THAT ARE THE SAME SIZE, LOAD INDEX, SPEED RATING AND TYPE (SUCH AS P-METRIC VERSUS LT-METRIC OR ALL-SEASON VERSUS ALL-TERRAIN) AS THOSE ORIGINALLY PROVIDED BY FORD. THE RECOMMENDED TIRE AND WHEEL SIZE MAY BE FOUND ON EITHER THE SAFETY COMPLIANCE CERTIFICATION LABEL OR THE TIRE LABEL WHICH IS LOCATED ON THE B-PILLAR OR EDGE OF THE DRIVER'S DOOR.



NOTE: ON SOME 4WD MODELS, THE INITIAL SHIFT FROM 2WD TO 4WD WHILE THE VEHICLE IS MOVING CAN CAUSE A MOMENTARY CLUNK AND/OR BRIEF RATCHETING SOUND. THESE SOUNDS ARE NORMAL AS THE FRONT DRIVETRAIN COMES UP TO SPEED AND IS NOT CAUSE FOR CONCERN.



Review the tire label for correct tire size and tire inflation pressures located at the B-Pillar of the driver's door.
If the tire size does not match the label, this procedure does not apply, follow normal Workshop Manual (WSM) diagnostics.
If the tire size is correct, ensure tire pressures are within specifications.
Raise the vehicle on the hoist, refer to Workshop Manual, Section 100-02.
Disconnect all wiring going to the transfer case and road test.
Is the shudder/binding present?
If the shudder/binding is still present, do not contine with this procedure, continue with WSM normal diagnostic for 4X4.
If the shudder/binding is gone, proceed to Step 7.
Raise the vehicle on the hoist and reconnect all the wiring previously disconnected.
Using a tailor's tape or flexible measuring tape and measure the circumference of all four (4) tires and record the measurements.


Calculate the average of the circumference of the two (2) front tires and calculate the average of the circumference of the two (2) rear tires.


If the difference between these two averages is greater than 1/2" (12.7 mm), front to back or side to side, replace the smallest circumference tire(s) and remeasure the tire averages. Refer to WSM, Section 204-04 for tire replacement.

the shudder was in a straight line, taking my foot completely out of the throttle at 75-80 mph. the stutter was turning right at 0-5 mph and yeah, about 45-50 on the cloverleaf.

Stupid question number one: what is control track? i have the 2h; 4h; 4L knob on the dash. the wife's explorer has an "Auto" button along with 4h & 4L by comparison

Stupid question number two: is tire circumference measured under load or with the wheels in the air for this calculation or would it even matter?

Rooster said:

taking my foot completely out of the throttle at 75-80 mph.

Click to expand...

You could have a multitude of problems going on here. How new are your tires? Did they balance them correctly? The high speed shudder when you let out of the throttle sounds like a tire out of balance.

Ryan

Rooster said:

the shudder was in a straight line, taking my foot completely out of the throttle at 75-80 mph. the stutter was turning right at 0-5 mph and yeah, about 45-50 on the cloverleaf.

Stupid question number one: what is control track? i have the 2h; 4h; 4L knob on the dash. the wife's explorer has an "Auto" button along with 4h & 4L by comparison

Stupid question number two: is tire circumference measured under load or with the wheels in the air for this calculation or would it even matter?

Click to expand...

For the control track, look at your brake booster, if it has a solenoid mounted on the face of it, control track. Tire circumfrence would be the tires in the air with correct pressure. 45 or 50 is around the speed that your converter clutch locks and unlocks. The low speed stutter may be the 4x4 staying locked.

i had a problem similar to yours it only happen every once and a while. after months of worrying and cussing i figured it out. i had a rear brake caliper that was not releasing all the way and after hard run ie....75-80 it will overheat and start sticking to the rotor. replaced it and never had the problem again. finnaly noticed it because of the heat it was giving off one day when i was standing in front of it talking to someone