Hey, i'm a noob just joined but anyways hope you guys can help me out so here goes.

I got an 01 ranger 4.0 4x4 with the 4R55E. It's got about 120,000 miles and has always shifted firm with no sign of wear or slipping... Bout two months ago my overdrive and reverse started acting up. All forward gears work when shifting manually...1st...2nd...D...O/D. Overdrive only kicks in when you are going bout 50 down the highway. I can turn the o/d off and drive around town but i still have to do it manually if i want to get to drive and when i come to a stop drive will kick back out. It's never kicked out or slipped in 1st or 2nd. Reverse is real weak and not fully engaging. Just slips enough to back me up on flat ground. I don't drive it very often so i didn't worry bout it till recently. I looked around and noticed that the vacuum line coming from the PCV valve going to the inlet rught under the throttle body had a hole in it right at the elbow right by the front inlet. I replaced this elbow with a plastic elbow and two pieces of vacuum line. Once i did that it worked perfect. Had all gears no slipping or manuall shifting. I was obviously pretty damn happy thinking a $5 elbow fixed what i thought was a bad tranny but after about two days of driving fine it started acting up again only this time it will engage in every gear just when you put too much load on it it will fall out of gear. So i guess my question is how much vacuum actually controls the engagement of the gears. Like i stated above it shifted perfect until now so i was suprised to think that my tranny had just shelled out so abruptly. Another reason i suspect a vacuum leak is because in reverse i can hear a pretty loud hissing noise coming from under the truck like an air leak but only in reverse. Any help is greatly appreciated. I've done quite a bit of research on here and sounds like you guys really know your stuff and i'm too afraid to take it anywhere and have them tell me it needs rebuilt if it's something small. I'm pretty mechanically inclined just kind of declined when it comes to trannys lol. Thanks

 

Oh, also the o/d light has flashed since it started acting up but now it is doing it more often. I took it to Autozone but the code reader wouldn't connect with my truck...i'm thinking bad fuse but i gotta find it first.

 

For the no codes problem see if your cigarette lighter is working. The test port & lighter are probaly wired to the same fuse.

 

Thanks that makes sense because my cig lighter doesn't work...i'll check it out

 

The 5R55E (a 4.0L gets the 5R55E) is controlled electronically, not by vacuum. I suppose in theory, a large vacuum leak can throw off some MAF input signals to such an extent that it might possibly it might affect shifting. That would be because "load" is such an important variable used by the PCM to determine the best shift strategy. But I doubt that is what is going on in your case.

Have you checked the level of the tranny fluid? When is the last time the fluid was changed?

 

i changed the fluid about a couple months ago...and i have checked the level a few times now. It just seems really ironic that fixing that vacuum line immediatly had an effect on the tranny and made it shift fine for a while and even though it still isn't shifting like it should it is better than before i fixed the line.