I am new to the board and not really mechanical but here goes. Driving home, I tried to pass a tractor and while accelerating rpm went up but the speed did not. Got home and checked fluid (recently flushed and changed) level was good. This morning I started up, put it in drive, it rolled forward but would not accelerate, rpm up but no increase in speed. I shifted to reverse to back in the driveway and it would not back up. I shifted back and forth and finally it pulled in 1st, then shifted to reverse and backed into the driveway and drove the Nissan to work. What should I check or what recommendation to proceed from here. BTW 3.0 with an auto trans. Thanks for any advice.

 

Welcome to the forum

Not sure what BTW 3.0l means?

What YEAR is the Ranger
3.0l was used from 1991 to 2008

All automatics run on Fluid Pressure, the ATF goes thru a pump driven by the engine/torque converter, and is pressurized to 175psi
This pressure is what engages the "gears"
Reverse requires highest pressure, 150+psi is needed
Forward needs 125psi at least

So you have a Pressure problem
The Valve Body routes this pressure to engage and disengage clutches and Brakes(bands)
It could be a major pressure leak or a mechanical issue, there are pressure test points on the transmission, you need gauges that can read up to 300psi just in case
Pressure test will tell you more


Why did you service transmission?
" recently flushed and changed"

Was it just time or did you notice a problem that caused you to get it serviced sooner than later?

 

 

 

2006 3.0l will have a 5R44E automatic

Best bet is to tow it to trans shop and have them test pressure.
Some OBD2 reader can get Transmission Codes, P07xx codes, but its not a solenoid issue which is all computer can really see, although it can detect wrong ratios in 2006

The transmission has full electronic shift control, but that doesn't mean an electrical problem will prevent transmission from working, even if you unplugged all the wires on transmission it would still get you down the road and shift into all "gears" except Overdrive.
Shifting would be harsh/hard, not smooth, but it would shift and would have Reverse

You may have lost the front pump(main pump), what do you think the total miles are on the transmission?

With engine OFF check trans fluid level, should be very High
Then start engine and check level again, should drop quite a bit if pump is working as it should