Ford: 1996 Windstar transmission surge, friction modifier, automatic shift

Question
Hi Ragu,
Particulars: 1996 Windstar, 145,000 km., Non agressive and gentle driving style. 3.8 Litre with overdrive transmission activated by the elec. switch on the gear shift lever. I don't beleive the trans filter and oil has ever been changed.

While accelerating through 70 km/hr at 2000 rpm the automatic shift in gears from 2nd to 3rd shows a surge in the rpm to 2300 or so before settling back down to 1500 rpm for the 3rd gear engagement.  The harder the acceleration the more radical the tachometer dances.

In overdrive mode all is normal operation.

A month and a half ago a similar surge developed when the trans oil was cold and the fluid levels were below the low level mark.  Added 3/4 litre trans oil.  Problem rectified but similar gremlins have returned as described above... oil level O.K. still.

Thanks Ragu,  Look 4-ward to your reply.

Graham  

Answer
Graham, I suggest you perform a transmission service first, replacing the filter in the transmission and replace the fluid with dextron atf also try using a friction modifier see how this works if the problem continues you will need to have the transmission checked  and pressure tested.