Jerks hard into gear only at Extremely high RPMS
11-30-2021, 10:57 PM
#1
Jerks hard into gear only at Extremely high RPMS
I have a 1997 f150 5.4 l 4x4 with approx 120,000 miles Here is a list of what I've done so far, in order, and what the current problems that I'm having are that have me stumped
1. Spark plugs
2. Air filter (same time as plugs)
3. The back five lash adjuster lifters on driver side 4. Oil change and new oil filter
5. New fuel filter
6. Fuel system cleaning at jiffy lube
7. All eight coil packs replaced
8. New throttle position sensor
9. New transmission fluid and filter (DONE YESTERDAY)
10. Removed shifter bolts to add thread locker and tightened (couple hours ago today).
The current problem and the reason for the transmission fluid and filter change is because my truck will only shift at abnormal and extremely high RPMs and when it does shift it jerks hard into gear. (Every gear not reverse). It idles perfectly and is throwing no codes. We used mercon transmission fluid and have not changed it regularly, but have had zero issues for last 3+ years until now. Also since doing the transmission fluid and filter change yesterday now the shifter on the column is very loose hence why I removed the bolts put thread locker and tightened, however shifter still loose.
1. Spark plugs
2. Air filter (same time as plugs)
3. The back five lash adjuster lifters on driver side 4. Oil change and new oil filter
5. New fuel filter
6. Fuel system cleaning at jiffy lube
7. All eight coil packs replaced
8. New throttle position sensor
9. New transmission fluid and filter (DONE YESTERDAY)
10. Removed shifter bolts to add thread locker and tightened (couple hours ago today).
The current problem and the reason for the transmission fluid and filter change is because my truck will only shift at abnormal and extremely high RPMs and when it does shift it jerks hard into gear. (Every gear not reverse). It idles perfectly and is throwing no codes. We used mercon transmission fluid and have not changed it regularly, but have had zero issues for last 3+ years until now. Also since doing the transmission fluid and filter change yesterday now the shifter on the column is very loose hence why I removed the bolts put thread locker and tightened, however shifter still loose.
12-01-2021, 08:52 AM
#3
Smarter than most Racoons
Do you have a code reader that can look at current run values?
If so, Please look at the throttle position sensor output and verify that when the key is in run, the engine is not started or running, and the accel pedal is in the idle position, the readout value on the meter is low. Less than 12%. Now push the pedal to the floor. The readout value should be nearly 100%, anything over 90% is acceptable.
A throttle position sensor that is bad will still let the engine run quite well but it will screw the trans shifting up in just the manner you describe. Brand new sensors can be bad. Why did the old one get removed?
There can also be an internal failure of a solenoid or wiring in the trans but those issues should provide a code and the check engine light should illuminate. The check engine light is operating correctly at startup?
What type trans fluid was used during the change. There are Mercon, Mercon V, Mercon LV, and Mercon ULV. I have heard of issues with people using Mercon, and Mercon ULV, but Mercon V and Mercon LV seem to be acceptable.
If I'm incorrect, someone will come along and correct me.
If so, Please look at the throttle position sensor output and verify that when the key is in run, the engine is not started or running, and the accel pedal is in the idle position, the readout value on the meter is low. Less than 12%. Now push the pedal to the floor. The readout value should be nearly 100%, anything over 90% is acceptable.
A throttle position sensor that is bad will still let the engine run quite well but it will screw the trans shifting up in just the manner you describe. Brand new sensors can be bad. Why did the old one get removed?
There can also be an internal failure of a solenoid or wiring in the trans but those issues should provide a code and the check engine light should illuminate. The check engine light is operating correctly at startup?
What type trans fluid was used during the change. There are Mercon, Mercon V, Mercon LV, and Mercon ULV. I have heard of issues with people using Mercon, and Mercon ULV, but Mercon V and Mercon LV seem to be acceptable.
If I'm incorrect, someone will come along and correct me.
12-01-2021, 09:00 AM
#4
Smarter than most Racoons
Also,
I hate a sloppy shifter.
Loose shifter can be caused by the shifter tube bushings being worn or falling from the straps; or the bolts that connect the shifter tube to the shift lever and the far end of the shifter (near the drivers feet).
You didn't indicate which bolts you tightened so you may want to check both.
I don't have a video for the shift tube to shift lever bolts but they are easy to find if you look at the far end of the steering column. If needed I may be able to get you a picture later today.
Video for the shifter bushings
I hate a sloppy shifter.
Loose shifter can be caused by the shifter tube bushings being worn or falling from the straps; or the bolts that connect the shifter tube to the shift lever and the far end of the shifter (near the drivers feet).
You didn't indicate which bolts you tightened so you may want to check both.
I don't have a video for the shift tube to shift lever bolts but they are easy to find if you look at the far end of the steering column. If needed I may be able to get you a picture later today.
Video for the shifter bushings
Last edited by ultimatenoobie; 12-01-2021 at 09:03 AM.