in both of my aero's I have had this "problem" so I dont know if its normal or not.

on the freeway, in overdrive, if I slowly accelerate, at a certian point the van slams back and forth into and out of O/D. RUMBLE WHAM WHAM WHAM.

but if I just give it a bunch of gas it shifts down "normally" "thunk".

my 91 3.0 did this, and I just learned to live with it. my 95 4.0 does it, but it has more power, so its way more violent!

whats wrong? normal, or not normal? cheap to fix?
thanks in advance!

 

It could just be a bad TPS. The TPS is just one of the things used to determine the shift into and out of OD as well as torque converter lockup.

 

heh, yup mine does it. ('91 w/ 4.0L)

 

I put in my tranny cooler, inline with the existing radiator, and auxillary one. overkill? i dunno, but the stock auxillary cooler is whimpy at best, only 2 pipes. like one U shape tube, how much cooling could that possibly do? the new cooler has 6 pipes in it, rated for 15,000 lbs.

today i also serviced the tranny... I changed the filter and gasket, and added "LUCAS stop slip". mine doesent slip, or leak, but I am planning on towing soon, so i got it as "insurance".

the tranny fluid was cherry red, and did not stink. and the innards of the tranny looked bright and shiny! not at all what I was expecting.

while i was under there I changed the oil and added dura-lube.

on my way home I tried my hardest to get the tranny to do its overdrive boogie, and it wouldnt. the worst i got was a little rumble, that no one would notice unless you told them to listen for it. also, you cant even feel it shift now.

if this "overdrive boogie" is normal, the LUCAS resolved it mostly. if its not normal, and something is wrong here, the lucas made it less evident for sure. either way it shifts much nicer now. and the dura-lube is like liquid horsepower.

lets see what happens to my mileage!

gas is $2.06 a gallon here today ARGH! is there such a thing as a "home refinery"?

 

I have a 88 XLT and it does the same thing. It seems to happen when I hit around 40 to 45mph and stay at that speed??? (It's like riding one of those horsey rides in front of the store.)

 

ok, update..

it still does it after all. my wife took the kids to WA 280 mile trip. she says it still bucks around when it decides to shift out of OD. it seems like it only happens when the tranny is warm. and now that I added the extra cooler, it takes a good 20 miles to get to that point.

I am going to see if its covered under my cheapo "internally lubricated parts" warranty. I doubt it, but its worth a shot.

any ideas??