Low transmission pressure

[oachs83]

I have a 02 ranger automatic 4spd 4x4 that has 187,000 on it. It will shift hard unless you are real easy on it. I flushed the tranmission because it needed it. When I hooked it up to the machine at idle the pressure gauge barely moved and was not pushing fluid out very fast. If I gave it gas the pressure gauge shot up around 15 -20 psi or so. Back at idle barely 1 psi. Does this mean I need a filter change? After the flush the first 5 miles or so it shifted very smoothly and the kickdown around 50mph was smooth. After that I tried the kickdown again and it started to shift hard again unless I am real easy on the gas. Anyone else have a similar issue or fix?

 

[Runnin'OnEmpty]

The low pressure could be caused by several things,
one of which would be a clogged filter.

To start with, I'd drop the pan, replace the filter,
replace the EPC solenoid, check for a torn valve
body gasket, and snug up the VB bolts.....

 

[bigcountry]

also when you take the pan off look and see if you find any thing thats not soppouesd to be there like clutch debris it will look like a film of sorts at the bottom of the pan and if it is an automatic the trans pump could be on the way out but i wouldnt go that far till you see whats in the pan but like runnin on empty said change the filter and see if that helps and if it does get some magnets to put in the pan and check the pan in about 40 to 50 thousand miles to see what they pick up

 

[McCormack]

Awhile back my auto trans started acting goofy, and it turned out to be the Vehicle Speed Sensor that was causing the trouble, so you might want to consider checking out or replacing your VSS to eliminate it as the cause of your trouble.

 

[bigcountry]

vss caused your trans to act funny that sounds weird but if its runnin better than it very well could have been but about the only thing th vss does is just tell the computer and speedo how fast to show. i had a vss go bad on a 97 f150 and it did nothing to the trans just made my speedo show 0 and 99 going like 45 or so. but thats a different story i could be wrong thou

 

[Bent Bolt]

When I hooked it up to the machine at idle the pressure gauge barely moved and was not pushing fluid out very fast. If I gave it gas the pressure gauge shot up around 15 -20 psi or so. Back at idle barely 1 psi. Does this mean I need a filter change?

This is very normal for these trannys. For whatever reason there is very little PSI in the cooler lines at idle. When flushing these trannys, I stick a small screwdriver in the throttle to bring up the idle speed a hair.

Your shifting problem is elsewhere.

 

[McCormack]

Yes, it very well could have been - my tranny was really screwed up - some of the time it would wind out and not shift when it was supposed to, and some of the time it would shift way before it was supposed to, and then it would lock up in third gear and not downshift until I almost came to a complete stop. Replacing the VSS returned everything to normal, so it would seem likely that the VSS had something to do with the problem.

 

[oachs83]

I bought the truck used so I wanted to change the filter anyways. It did not help but oh well. Yes a VSS or also TPS (throttle positioning sensor) could very well cause a tranny to shift funny. The tranny shifts at what the sensor tells it and if the sensor is goofy your tranny will be as well. I usually see a engine light on when these sensors go bad did you have a light? I scanned my truck and it is all clear of codes. but the ABS light is on once in awhile. The codes were C1230 and C1237. I replaced the rear speed sensor but it did not help at all. The code does not come on very much and usually shuts itself off shortly.

 

[Runnin'OnEmpty]

Ummmmm.....

Now that you mention the TPS...???

You can check it with a voltmeter; look
for a smooth transition from (about) 1v
to 5v on the signal wire when the throttle's
advanced.

These TPS' do wear out, and they won't
set a code as long as a signal (even a bad
one), is present.