Vehicle lags when accelerating and transmission will not shift down when needed. When it does shift down it feels like the engine is revving very high but its going nowhere

Question edited for clarity and spelling.
Question moved to model category from 'Misc'.

Check for Diagnostic Trouble Codes. check clutch operation if manual. Check transmission fluid if automatic.

my RPMs would go up but my speed
that the transmission

• it fails to up shift
• or slips (or both)

why not get the PCM scanned first. any obd2 scan tool
rent, borrowed,loaned, buy, or get it scanned. in a shop.
they key to this questions is RPM and speed
the question is clear and so is the answer.

you did not say only on hills
so on flat ground I bet you forget to count the gears
from 1 to 4, , the 2.>3 shift or 3>4 shift fails.
count them.

check levels per the manual yet.
does dip stick engine trans, smell burnt or look like TAR.
it is checked
HOT engine fully
parked
at idle
Cold <<<X<<<HOT
never above hot or below cold.
do not overfill any transmission ever. (

transmission is 4L60E TCM brain shifted,. and MUST SCANNED
if lucky , only a bad OSS output speed sensor.

Corrupt adaptive shift memory. Try clear and relearn.

https://youtu.be/jWMliD_3s3o

Hi Sherri,what kind of vehicle you have,need year,make,model.

Your clutch needs to be replaced.

ENGINE HESITATES WHILE ACCELERATION

LOSS OF ACCELERATION

It can be fuel pressure issue or it's the problem with accelerator pedal or its clogged filters causing there.

There are many other possibilities. I suggest you to go through the list of help links mentioned below, these will help you to confirm where the actual fault lies: -------

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Acceleration lag problem?

http://repairhelpcenter.blogspot.com/2012/01/acceleration-lag-problem.html

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Jerks and Hesitates During Acceleration?

http://technoanswers.blogspot.in/2012/07/2004-dodge-town-country-jerks-and.html

-----------

Loss of acceleration?

http://technoanswers.blogspot.in/2012/02/loss-of-acceleration.html

---------

Headlights flickering and car hesitates to start?

http://howtobyme.blogspot.in/2012/02/headlights-flickering-and-car-hesitates.html

--------

How exactly the Vehicles Accelerator Cable works?

http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-cable.html

-------------

How exactly Vehicles Accelerator Pump Diaphragm Works?

http://repairhelpcenter.blogspot.com/2011/11/how-exactly-vehicles-accelerator-pump.html

--------

2000 Toyota Avalon: Engine Lean Codes and Knock Sound on Acceleration?

http://whatisbyme.blogspot.in/2012/05/2000-toyota-avalon-engine-lean-codes.html

---------

2004 Toyota Avensis: Acceleration And Deceleration makes noise on Front End?

http://whatisbyme.blogspot.in/2012/05/2004-toyota-avensis-acceleration-and.html

---------

Wheel hop under hard acceleration?

http://technoanswers.blogspot.in/2012/04/wheel-hop-under-hard-acceleration.html

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2009 Chevy impala accelerator pedal sensor?

http://technoanswers.blogspot.in/2012/02/2009-chevy-impala-accelerator-pedal.html

---------

Nissan Pathfinder stalls and bucks on Acceleration?

http://technoanswers.blogspot.in/2012/02/nissan-pathfinder-stalls-and-bucks-on.html

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These details will help.

Thanks.

If you are driving any front wheel drive vehicle, what you are feeling is called torque steer....sometimes it's from poor design but it can also be caused by a broken engine or transmission mount allowing the engine/trans assembly to shift under load or when removing load.
You can do a quick test by holding the brake down firmly and in gear, press down on the gas. have someone watch (from the side of the car ONLY) and see if the engine shifts. Do in both drive and reverse.
Be very careful when doing this that the car does not get away from you and do not hold power for more than about fifteen seconds at a time or it can overheat the transmission. This only works in automatic trans cars... for stickshift ones you need to move the engine with a long pry bar.

is this a 4cyl or V6...how many miles??sounds like the transmission isn't shifting to lower gears....is there any warning lights lit on your dash??

Your going to need a scanner hooked up to look at data. There is no other way without guessing.

Sorry to inform you that it sounds like your transmission needs servicing.
Check the fluid levels and replenish if level is down.
If after doing this,the car still wont shift properly or smoothly,,then you will have to take the car into a transmission mechanic.