95 Taurus trans hunting in drive

[0176]

 ???My son is driving my 95 Taurus 3.0 AXOD. Trans rebuilt with updates a little over a year ago. He told me it was slipping, but when I drove it it shifted fine until cruising at about 35 mph then it stsrted downshifting then upshifting back and forth  until you eased off of the gas. Fluid is clean and has no unusual odor. Any ideas.

Thanks, Bill

[0176]

If you accelerate very slowly there is no problem, but if you aggressively accelerate or push down on the gas it jumps in and out of passing gear.

[jasonn20]

When it is acting up is the speedometer erratic ??   Is the CEL on ?

[Transman]

It appears to be a "Control" problem from your description. A scan for codes would be helpful as well as any datastream info. It could be anything from a bad connection, poor ground to a bad sensor (TPS, MAF, Input speed or output speed). WAY too many possibilities to guess at. The majority of possibilities are minor in nature but can become very serious is allowed to continue. I am assuming there is no trans warranty left? Post any results as well as any recent work performed or additions to the vehicle, Transman

[0176]

BTW AX4N not AOXD. Speedometer is fine no CEL.

[0176]

Transman, No recent work, No warranty left but they are friends and will check it out. I am trying to decide if I should drive it to work and drop it off to be checked. Or, I will bring the scanner home from work and check it out tomorrow afternoon. I am not sure about driving it 45 miles to work.

Thanks, Bill

[Transman]

That's a tough call, if they will let you borrow the scanner, then I would probably recommend that as first option. You may be able to determine engine problem or trans problem from that information. Then the next step might just become obvious. I would check the "Basics" first, vacuum lines, connections (all that you can lay your hands on), including the battery. Check the alternator for "AC Ripple", pull a spark plug, check your plug wires for burn through or "Critters". These fords were well known for pcv vacuum lines sucking in also. ANY performance problem WILL manifest itself as a trans problem also. Post results, Transman

[0176]

Transman, I'll bring the scanner home and post tomorrow what I find.

Many Thanks, Bill

[0176]

Transman, Brought scanner home and had one KOEO code related to the VSS, I did not write it down and the number slipped my mind, but it went away and the car drives and shifts fine now. I hate intermittent problems. I now have a better idea what to do when it returns. Thanks for the help.

Bill

[0176]

Transman, Code 452 is intermittent. Car drove to store and back with no problems. Earlier it acted up and set the code. I think I kept the VSS from a core trans that I bought a while back.

Bill

[Transman]

That's a good start. Connections are always a problem, wire routing also an issue ( does the vss wire go near secondary ignition wires or coils?). Does this engine show any misfires? (Mode 6 may be necessary to find out)(should be test 53 or 54 in mode 6).
 The good thing here is when it IS working, it IS working well. This means the trans is capable of working well and it probably IS an electrical problem in nature. Post results, Transman

[0176]

Transman, The builder at the shop that rebuilt the trans gave me a VSS, which I installed today. It appears to have the problem. He also suggested inspecting the wires, which appeared to be ok.

Thanks, Bill

[Transman]

Good Job and thanks for posting your results. It's an obvious point that a very minor part can make a very serious problem, Transman