HELP! Tranny Prob.

[Fender5]

Hope you guys can help shed some light on this. I have 2 problems with my 96 ex 4.0, 99,000 miles. First, it
seems to have a miss or surge when in drive at an idle, I assumed it may be the IAC which I have not replaced yet.
It does not do this all the time but, when it does it seemed to affect the take off from a stop -- it would sorta jerk
some as the engine missed. As I said, it does not do this all the time. My second problem I noticed big time today.
I was making a trip through some very hilly terrain and the tranny started jerking like it was searching out a gear
from 45 - 55 mph when going up steep hills. It did this for the entire trip when hitting the hills (30miles). It was
not noticeable once I got back to less hilly terrain. It was a fairly violent jerking action - kinda like it was
downshifting but then going back into a higher gear quickly. I don’t know if the 2 are related but, thought I would
throw in the first problem to be sure they weren’t. It does downshift OK on strait roads and shifts seem OK but,
obviously when going up hills their is something not right. I appreciate any advice on this as I am clueless about
the tranny.

 

[Opera House]

Doubt its the transmission

At first I thought I had a transmission shudder in my '97. It was only a bad plug, even though it was put in only 4K earlier. It will occur under load when the engine is typically under 2K rpm. This is when it takes the highest voltage to fire. In my case #4 plug is bad because of a lower intake manifold leak.

 

[Fender5]

Hmmm, that is somthing to check, thanks. Anybody else got any suggestions, I did a search before I posted but, the only thing I could find like it had problems at low speeds like slipping from first to second which mine does not do. Could this be a computer problem -- like the computer is not letting the tranny downshift properly. As I said, I am not a tranny person and the Hanes manual is useless on this problem. I am concerned since my wife drives this one to work. I am debating on taking it to Ford but do not know how much good that will do. I had my truck at the local one for some work several times and ended up fixing it myself.

 

[Mbrooks420]

Did you try taking it out of OD? When your trans shifts too much on hills you are supposed to turn off the OD.

 

[Fender5]

No, I did not try that. Might be the problem. Would that cause it to have a sort of violent jerking action? Don't want to sound dumb, but I have never had this problem with my truck, which also has overdrive. I really appreciate all your help. If it gets to bad and I have to take it in, I like to be armed with as much info. as possible.

 

[Runnin'OnEmpty]

It could be the TPS (throttle position sensor). If you have a multimeter, it is easy to check.

 

[Mbrooks420]

The shifting shouldn't have been violent, just too often. The TPS could be at fault like Runnin'OnEmpty suggested.

 

[Fender5]

It was very noticeable I'll put it that way. Like if you had a bad miss in the engine and was trying to drive anyway. Like I said, it was only doing this uphill. The more I drove in this hilly terrain the worse it got. I went to the mountains this past April and it never did this. That is why I was concerned about it. I do have a multimeter, does any one know what it (TPS) should read? I thought it might be a computer problem - not telling it to downshift properly.

 

[elguapodh]

your haynes manual covers what to check for with respect to the position sensor. it will tell you to remove the plug, then check continuity between different pins depending on what gear you are in.

 

[Fender5]

Thanks for all the help. If anyone has anthing to add, I more than welcome the info. I will have to wait until the weekend to check this stuff so far and will post my results in case anyone has a similar prob. Once again thanks, I was kinda feeling my tranny was going but, now feel like I may luck out.

 

[Runnin'OnEmpty]

Fender, I suggested a bad TPS because the trouble happened while you were going uphill. The throttle would be opened more, and the TPS would be at a different position than at cruise.

TPSs' do wear out. They are basically a variable resistor and the most wear occurs where the throttle moves the most; at part throttle settings.

Like egula says, the Haynes manual has a procedure for checking the TPS. In your case, pay close attention to the signal wire voltage. It should increase from about 1v to 5v SMOOTHLY, as you open the throttle. If your's is bad, the voltage reading will be erratic.

Good luck.

 

[Fender5]

Thanks again. I was thinking that the TPS was easy to get to on the 96 4.0, haven't been able to check due to long hours at work right know. With the miles on it, I may just replace it. I hope that and/or the IAC will cure my problems. I have cleaned the IAC out once about a month ago so, would it be cheaper to replace the TPS first? The cheapest I have found the IAC is $78.

 

[Mbrooks420]

You may want to contact Ford parts network who advertises thru this site. I think I paid 50 for mine.

 

[Fender5]

Thanks, I'll try that.

 

[Fender5]

Well, I replaced the TSP this past Sunday, cleaned the MAF and IAC. No good, still has the problem. It has had a tune-up in the last 6 months with plugs, fuel filter, etc. I am at a loss. I have also replaced the EGR valve and the DPFE sensor in the last four months due to what I thought was a rough idle. The only other thing that I have thought of would be the O2 sensors. Any other advice before I break down and carry it to a shop?

 

[TPLYNCH]

Just a shot in the dark.... Have your alternator tested. If it is going south, it can cause tranny shifting problems.

 

[Rocket250]

Fender5 have you had any resolution to this? My Eddie Bauer is having the same problem, when crusing at 40-45 under light throttle it has the same violent jerk you are describing. Mine happens on any incline be it large or small. Turn the O/D off and no problems. I changed the fluid/filter and it did not help. Truck has 40k on it. Any help would be appreciated. Thanks

 

[dogfriend]

I am having the same symptoms that are being described here. I first noticed the problem on a sustained climb uphill for about 25 miles. Every so often there would be a small jerk, like the trans was downshifting but immediately back up again. It happens both with O/D engaged and with O/D locked out. I don't see any rev change on the tach when it occurs.

Now the problem is sometimes happening on flat ground at crusing speeds.

Please update progress and/or elimination of causes and I will do the same as I try to diagnose this.