Automatic Transmission Troubles

mrprotoplasm · #1 08-22-2013, 04:27 PM

Hello, I'm new, and I have joined your community as a man in need.

I have had this Ranger for 5 years, and this is the first real trouble I have run into, and I hope it isn't that "real."

1998 Ranger Extended Bed 2x4, Automatic 2.5 L 4cyl. Her name is Truckenstein.

So I am driving like normal, and after about 45 minutes of my hour commute, on the highway, the truck starts feeling like she is going in and out of gear around 65mph. Then I start to slow down, and it downshifts with no problems, until BOOM, it goes into first like I got rear-ended. Now just about every time I enter and leave first, it seems to drop it into gear with a vengeance, it does feel like I've been hit each time with a little love tap from the car behind.

Oddly enough, shortly thereafter the stupid P0171 code pops up, something I've struggled with in the past because of a stupid aftermarket CAI, which I have removed in pursuit of solving this problem. I replaced my MAF sensor and removed the aftermarket CAI for a stock system, with a plain ol' paper filter (no oiled filters).

This did nothing, so I changed the ATF fluid and filter, also, nothing.

Finally, swapped out the ABS sensor at the rear differential. Nothing.

I have heavily researched similar problems and I cannot find one exactly the same, it seems to shift okay occasionally, like 1 in 4 times, but I can't figure out what is different when it does this. It seems to get worse when it warms up, as each step I would go diagnose it and think it was fixed, until I kept driving for a few minutes. It doesn't send to shift as hard, but I haven't driven it to the extent I normally would to let it warm up either. I have NO problems if I just drive it in 1 or 2, as there is no shifting going on, the problems are only in and out of first and the strange slipping in the highest gear.

No codes are currently thrown or pending. I have not had a flashing O/D light. These are the two things that everyone else with tranny problems has that I don't have the luxury of having (thus helping to direct my solving this issue).

I have found this forum that speaks of replacing the O/D Servo, but he says it is on the Drivers side, and it's not, so who knows if anything he says is valid...

http://www.therangerstation.com/foru...ad.php?t=62415

Any thoughts on this predicament, my new friends?

Thanks for your time.

mrprotoplasm · #2 08-23-2013, 06:03 AM

RoberticusMaximus · #3 08-23-2013, 06:07 AM

i'm curious to know what the problem is. subscribed!
i wish i could help...

reconjb · #4 08-23-2013, 06:13 AM

when you changed the fluid did you notice any gasket material in the fluid?

these trans have a fairly common problem with blowing the valve body gaskets which can really screw with the shifting habits of the trans depending on where they blow

mrprotoplasm · #5 08-24-2013, 08:24 AM

The fluid was pretty clean upon changing, its been about 3 years and not even 30k miles since the last change. Nothing unusual about it and no debris to be found. Would there be more severe symptoms with something like a valve gasket issue?

mrprotoplasm · #6 08-26-2013, 05:44 AM

Any more advice? I guess I'll be heading to AAMCO this week...

Muscleford · #7 08-26-2013, 04:37 PM

I had similar problem with a '94 T-Bird. It shifted from high to low gear on the interstate on my wife at 50 mph. Long story short it turned out to be the trans range sensor. I don't know if your trans has that or not.

mrprotoplasm · #8 08-27-2013, 03:42 AM

And you didn't get any codes?

mrprotoplasm · #9 09-01-2013, 05:43 AM

AAMCO says its the PCM, they want 900 to replace it. I'm going to do it myself, it seems like an easy replacement, so long as I get a direct ECU replacement.

My question, and perhaps I need a new thread for this, is my car does not have the special PATS keys for the ignition, but it does have a weird second "key" that plugs in under the steering wheel, like a separate computer chip. Will this give me trouble?