Early shifting in OD

[JChrisMarion]

Hey guys, I have a 97 Explorer AWD and the last month this problem has started and becomes more frequent. Doesnt matter hot or cold, when you are driving under light acceleration/cruising it shifts into overdrive to soon. Well atleast it feels like it. I am not over 2000rpms and it shifts into OD making it feel like its struggling to go. Barely press the gas and it quickly downshifts back running smoothly and shifts about 2200rpms. This is ONLY in OverDrive. If I turn overdrive off, not a single problem. Perfect shifting. Thought it was a fluid/filter problem, but that did not fix it. I thought there was maybe a TSB for this and maybe it needed to be reprogrammed to shift later. I also searched and found this http://www.explorerforum.com/forums/showthread.php?t=174722 thread. Hence the fluid/filter change.

I honestly dont believe this to be a internal tranny problem. Its not your typical shudder, just feels like its struggling in OD to push this AWD pig at those rpms going MAYBE 40-45mph. If you drive normally, no problem. Drive like a grandma trying to conserve gas and here it comes. Easiest way to describe it is like driving a manual pickup towing something. Shift from 1-2 and then 5th. THAT type of "ohh crap I cant pull this thing".

Thanks,
Chris

 

[Glacier991]

Remember, the shift to OD is commanded by the computer (PCM). It,in turn, relies on inputs to tell what is going on in the real world. If it gets bad inputs, it sends bad outputs.

I am thinking you have a sensor issue, most likely speed sensor. (The MAF also comes to mind but because it is part of the emissions system it WILL usually set a flashing code most of the time). Sometimes you can set a code and the OD light will NOT flash (rare but can happen - speed sensors are notorious for this). Can you get a free code scan someplace?

Somehow our 'puter is commanding a "too soon" shift is my guess.

[ps. this is a case where the trans tester would be worth it's weight in gold... for those trans tester curious enthusiasts.]