99 Taurus odd shifting issue

I have a 99 Taurus. Had the car about 2 and a half years. When I bought it the previous owner said he had the transmission rebuilt a year before,(he did have the repair receipt). Some times, not all, after you’ve you had to accelerate hard (like getting in a highway),or after a long drive, the car starts to shift hard. It also seems to go from first then neutral then second when taking off from a stop. A quick hesitation,rpm’s go up a little,then shifts. I can park,turn the car off, sit a few minutes and it goes back to normal shifting. Anyone have any idea what this issue is? I thought about changing the filter and fluid,but I’ve known a few people that have done this while having issues, and the transmission went out soon after! I can’t afford a rebuild! What to do? What to do?

Doing a drain and filter will not hurt your tranny. A flush can hurt it. Forcing fluid aganst the pump and junk into the valve body is not good. Your friends trannies were probably dying and then they tried the fluid replacement as a last resort.

You might want to try to have the transmission fluid serviced. I had a Thunderbird come in with the same problem and a fluid exchange fixed the problem.

Contrary to what people believe, a fluid exchange machine doesn’t pump the new fluid thru the transmission. The engine is started and the pump within the transmission is what exchanges the fluid in the transmission.


I did have one person tell me the problem is with the speed shift sensor. The Tranny is the only part of a car I dont do,so I have no idea. Is this a possible reason?

The computer uses the information from the Vehicle Speed Sensor to determine shift points.

If there were a problem with this sensor the Check Engine light would be on. And the speedometer wouldn’t work or act erratic.


Changing the fluid and filter won’t cause the transmission to fail, unless it isn’t done correctly of course. For example, sometimes there’s a seal that needs to be replaced with a new one as part of the service, otherwise the new filter can fall out and drop into the pan, allowing dirt into the transmission internals. But if the job is a proper service and done correctly and the correct fluid is used and filled to the correct level, that can only help your transmission. But your transmission still may fail soon after. The reason folks report that they serviced their transmission, then it failed, is b/c they serviced it b/c it wasn’t working correctly, so it’s not that surprising in some cases the transmission will fail soon after that.

I think your best bet is a proper transmission service (and in the future repeated, spaced every 30 to 50K miles), including filter replacement. And start saving up a little money each week, as a transmission rebuild may be coming at some point.

So there are about 3.5 years on the rebuild. But how many miles? How many on the car in general too?

If it starts to shift hard after a while, and do other funky things, AND IF turning it off an back on returns it to normal - then the computer “knows” what is going on - or at least sees a problem. It is maxing out the line pressures and that usually comes from the detection of too much slippage on the shifts.

Is the check engine light on? If so you can get the codes read for free at many auto parts stores. If you do this write down the codes in their exact form like “P0123.” If the check engine light is not on then, it would be a good idea to have it scanned with better equipment than is found at most of the auto parts stores. Your best bet would be to have it scanned while it is acting oddly. This isn’t always easy.

My own off-hand guess is that you’re actually headed for another rebuild. If those transmissions aren’t serviced regularly (e.g. pan/filter service every 30K), they are not known to last a real long time.

There are 2 types of exchange machines, 1 that is a bladder that uses the tranny pump and 1 has a pump and forces fluid throught the tranny. I would not use the 1 that has a pump. http://mdhmotors.com/transmission-flush-when-and-when-not-to-flush-transmission/

Service engine light has never come on. I’ve checked for codes and there are none. It doesn’t happen very often. Maybe once a week. I’m hoping it’s just gunk getting into the valve body or something. It’s time for a filter, fluid change anyway. I’ve put just about 30,000 miles since buying it, so…otherwise it runs like a new one. Very well maintained.

How did you check for codes? Not all code readers are created equal.

Certainly drop the pan and all. That never hurts and can only help.

Automatics actually use the signals from a number of sensors to determine shifts, only one of which is the vehicle speed sensor. It also needs to know the engine speed, the throttle position, and a few others… .including the tranny fluid temperature.

I agree with the pan drop and fluid change. I agree that a “flush” is not a good idea.
Check the level of the fluid before the servicing and its condition after it’s removed. Post back with the results.