I have 1992 Ranger with the 4 speed w/OD transmission. When the unit is cold and you are driving down the road and come to a stop. Trans will act like it has gone into netrual. Shut the engine off and it will work just find. Once it is warmed no issues. Temp sensor changed, has no MAP, and ideas where to look next. TPS is new as well.
GE

 

Welcome to FTE.

How many miles on this tranny????

How is the tranny fluid level & fluid condition????

When last was the tranny filter changed & a complete tranny fluid pump out done & what fluid was used????

 

1. Miles on unit 129K
2. Filter and full fluid change out every 30K (not just the pan but full fluid changes with flush)
3. Unit is lossing and electrical signal. Don't know where or why.

I have onwed this truck from new. Maintenance on the unit has been done on a very regular schedule. I normally see mileages on my units in excess on 200K without major repairs. Last car was a ford and it went 300K no repairs. Maintenance is key!

 

You get an "attaboy" for tranny mainenance to Fords severe service schedule!!!!! Way to go!!!

Your right, scheduled maintenance is key to long & reliable vehicle service.

I too, have always serviced my trannies at or before Fords severe service call outs & Still I've had up & down hang shift problems, that were apparently deposit related, as they favorably responded to a detergent additive, driving it until the problem abated, then doing the pan drop, filter change & full fluid pump out, all with Motorcraft filters & fluids!!!!

My problems return on a regular basis, usually around the two year mark, after a service & another shot of detergent, drive it until it stops acting out & another filter & fluid pump out, will square it away for a while!!!!

My fluid has always looked fine, the tranny pans always had very light clutch deposits, as did the magnets, the filters have always been clean, no signs of sludge, gum, or varnish anywhere, but Still I've had up & down hang shift problems.

I've come to suspect maybe Motorcrafts fluids, or ad pack recipe aren't up to the task????

So don't dismiss it being a deposit related problem, just because it's had regular maintenance.

Could be a sticking shift solenoid, from a little gum, varnish, or sludge, or something in the valve body, ect, mucking & hanging things up & causing problems.

Tolerances in our trannies are close, so it doesn't take much in the way of deposits, to cause mischief.

If you know for sure it's electrical, inspect the wiring to the tranny, for loose or corroded connections to the TRS & solenoids & measure the shift solenoids resistance.

if you come to suspect deposits, maybe consider trying 1/2 to 1 can of Seafoam Trans Tune (don't over fill the tranny) drive it as you normally would & see if you get positive results.

If so, it's likey deposit related, so drive it until the problem clears, then change the tranny filter & do a full fluid pump out.

The Trans Tune is just a detergent, no seal swell agents to get after gaskets, seals, plastic, or metal parts.

Others have had good luck with Auto-Rx for trannies. It's an ester based product, that gets after deposits, to slowly dissolve & hold them in suspension for the tranny filter to grab, or until we change the fluid at the prescribed time, which now is 3K miles, after adding the Auto-Rx.

It's more expensive than the Seafoam Trans Tune, but may do a more thorough cleaning on gum & varnish deposits & I'm about to use some on my 94 Taurus AXODE tranny, because of recurring hang shifts over time.

Also about to try another brand of Tranny fluid, like Texaco Multi-Vehicle, that meets Fords Mercon-V/Mercon specs & has a higher vicosity index.

A whole bunch more thoughts to ponder, let us know how it goes.

 

With that much age, even with the low miles, the seals may have shrunk or hardened. I would follow Pawpaws recommendation. If you are using Mercon III, try Mercon V. The newer fluid has more friction modifiers and has a stronger detergent add pack. It is fully compatible with trannies that use Merc III.

 

I may have miss stated the problem. The trans act as though it was placed into natural. Only when it is cold and only when you are letting off the accelerator peddle. Now having said that, it only does this once in a blue moon. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
I have inspected the valve body (I might add here that I have 40 plus years designing & repairing all types of mechanical apparatuses from A-Z. I hold several journeymen’s cards in various trades and an engineering degree) and all valves appear to be free and correct. There is no layers or film that would be consistent with dirt of any kind. I have even checked the fluids coming out of the unit after a flushing, by running through a 5-micron filter and see nothing in oil. <o></o>
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So with that any ideas, I read where there seems to be some issues with brake systems and ECM modules as well with some of these problems, thoughts on this?<o></o>
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Ok, if you have a bad MAF sensor, it can cause some issues, however, the computer does not have the ability to shift the trans into neutral, those are all internal hydraulic functions. What the computer does have control over is the 3-OD shift and the torque converter lockup.

 

I agree with Khan Tyranitar that it sounds like an internal tranny problem.

Could be the torque converter acting out, or the forward clutch piston hanging up, a solenoid problem, or electrical connecion to it, or a line pressure problem from a valve hanging up, ect.

So maybe if your of a mind to, do some pressure checks, although with the problem being intermittent, like mine are, trying to trouble shoot the danged thing will likely be hit, or miss.

Thats why I finally bit the bullet & decided do something I rarely do & that was to try an after market tranny detergent (SeaFoam Trans Tune).
I did first ask a long time tranny Tech to review it's recipe & he blessed it with the comment that he didn't see anything in it that would get after the clutch material, seals, gaskets, hoses, plastic, or composit parts, or metals.

Even then I was so hesitant I only added 1/2 a can!!!! BUT I got some positive results in three days & the hanging up/neutral feeling down shifts when coming to a stop, completely cleared up in about three weeks, so thats when I did my pan drop, filter change & first full tranny fluid pump out. All that was in 98, on my 94 Taurus AXODE tranny!!!!

I know your not of a mind to accept that deposits could be a problem, but gum, varnish or sludge can form on heated parts, hang them up & still not show as particulates in the fluid, or after the fluid has been filtered.
So imo, don't take that possibility off your suspect list yet.

But with the vintage of your tranny, it could be electrical, mechanical, hydraulic, seal, or gasket related.

Will the tranny hold back firmly in 1st gear when coming down a grade????

 

Yes, all is normal, until it is cold or other wise in one of the stated conditions. For the cost of the materials suggested, I will try this. But given the nature of the conditions inside the unit I doubt this will do anything. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
Having some very complex aircraft hydraulic systems apart that were using 5605 hydraulic oil, which can be gummy and seeing more dirt & film in them then I saw in this unit and they were still working, we will see. Might make a believer out of me about after market cleaners etc:<o></o>
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If I find the issue on this in the mean time I will pass along any resolution I find. <o></o>

 

On a '92 the electronics only control overdrive and torque converter lockup. Your problems lie inside the trans.