93 Transport Not Shifting 1st to 2nd Then OK Again

[tinkering]

!993 Transport 3.8 L

Starting out from stop it seemed to get noisy and was very late shifting to 2nd. Slowed down and tried again; this time it did not want to shift to 2nd at all. Brought it home slowly.

Trans fluid was right up. I did another road test, running it manually through the gears so I could easily hear and feels the shifting. 1-2-D-OD perfect; did this twice of thrice. Starting out from stop on the highway a couple times, it shifted up perfectly. I did some kick-downs and manual shifting; everything is working fine.

Could this have been a linkage problem? Could running it manually through all the gears smarted up the linkage or something? Could it be related to the 'modulator valve'?

[LMP]

A loss of vacuum at the modulator is taken as full throttle...this might retard though probably not totally inhibit shifting ..
MOdulator at rest (engine stopped, no vacuum) takes the full throttle condition...may be it could have frozen in that position...?????
but anyway, it seems all is back to normal operation now.....
Yes, I've seen linkage problems with son's Grand Prix GT 2000..but then did not return to normal by itself....
report any sequel....

[tinkering]

Originally Posted by LMP

A loss of vacuum at the modulator is taken as full throttle...this might retard though probably not totally inhibit shifting ..
MOdulator at rest (engine stopped, no vacuum) takes the full throttle condition...may be it could have frozen in that position...?????
but anyway, it seems all is back to normal operation now.....
Yes, I've seen linkage problems with son's Grand Prix GT 2000..but then did not return to normal by itself....
report any sequel....

I am going to replace the mod valve; I will let you know if the problem returns.
It seems less likely to me too that it is the linkage when it returns to operational.
Maybe it is a sticky pop valve somewhere?
Thanks

[Headnsouth]

It wouldn't hurt to run a trans cleaner thru it and the change the fluid and filter. I've had good results Seafoam trans tune.

[tinkering]

Originally Posted by Headnsouth

It wouldn't hurt to run a trans cleaner thru it and the change the fluid and filter. I've had good results Seafoam trans tune.

That's a heck of an idea thanks for that.
I bought the vac mod but haven't put it on yet; it was snowing every time I had the chance.
It shifting hasn't been troubling lately but I am still going to change that vac mod, and clean/change the fluid. Thanks again.