1997 Explorer XLT Late Shift in 1 st

[bud4ya]

I have a 1997 Ford Explorer AWD, Auto with od, V8. The problem that just started happening is when I start off from a stop the RPM’s will go up to 3,200 RPMs before it shifts to 2nd. Note this problem is under light acceleration. Typical when it is running right I step on it normal it goes up to about 2K RPMs and then shifts to 2nd and the RPM’s go down to 1.5K.

Last time I brought it to the mechanic and left it they called back and said it was not doing what I said. I picked it up and it ran fine for weeks until now.

Do you think it is the tranny, vacuum line for tranny or is there a speed module or something that needs to be replaced? I am far from a mechanic so these are just guesses.

I tried searching to see if other have had this prob and the fix and cannot find anything like my exact isuue.

Like I said I will have this problem and then it will go a way for sometimes a day and sometimes weeks.

The fluid is full and was changed within the last 10K miles.

Any suggestion would be appreciated

Thanks

 

[Glacier991]

Well, it could be a few things. 2nd gear in the 5R55E is created by "overdriving" 1st gear. This is accomplished by applying the OD band (Bent Bolt will tease me because FORD calls it the "Coast Clutch" and the "Coast Clutch band") The PCM turns ON the SSC solenoid (this same solenoid is also used in 5th gear, which is also an OD band application gear). You could have something "sticking" in the Valve Body intermittently, or your EPC could be getting weak. I'm thinking it you have more than 100K on your tranny you have an EPC that is slow or weak to respond.... which might explain why you are not getting a MIL or Check Engine light. A bad SSC *should* throw a code.

If you have not done the 5R55E Valve Body Rebuild Diary, you might consider doing so, and replacing the EPC in the process.

One question, how is 5th gear ?

 

[bud4ya]

It is an auto so do I have 5th? I have 120K miles. The only issue seems just going from 1st gear to second under light acceleration. It acts like I am flooring it and the RPMs climb up to 3k or so before it shifts
to 2nd. Then it goes away for sometimes days or weeks and runs fine.

Also what is EPC?

No check engine light oon

Well, it could be a few things. 2nd gear in the 5R55E is created by "overdriving" 1st gear. This is accomplished by applying the OD band (Bent Bolt will tease me because FORD calls it the "Coast Clutch" and the "Coast Clutch band") The PCM turns ON the SSC solenoid (this same solenoid is also used in 5th gear, which is also an OD band application gear). You could have something "sticking" in the Valve Body intermittently, or your EPC could be getting weak. I'm thinking it you have more than 100K on your tranny you have an EPC that is slow or weak to respond.... which might explain why you are not getting a MIL or Check Engine light. A bad SSC *should* throw a code.

If you have not done the 5R55E Valve Body Rebuild Diary, you might consider doing so, and replacing the EPC in the process.

One question, how is 5th gear ?

 

[Glacier991]

EPC = electronic pressure control solenoid. It controls hydraulic pressures within the transmission via the car's computer. A problem child in these transmissions... NOT long lived on average. There is a ton of info on here if you care to take the time to read up on it... but it rather sounds like you will have a shop do what you decide do anyway? (which is fine).

 

[bud4ya]

I have narrowed it down a little more. It is back to doing it again today. It seems like when it is really cold out side it acts up everytime. From 1st to 2nd it goes up to 3100 RPMs and the same from 2nd to 3rd. I have not tried to get on the highway with it. If I manually put it in 1st gear and shift to 2nd around 2K RPM's it does fine. Then when I am going out of second I put it back into drive and the same prob is there.

With these added items you still think it is the pressure solnoid?

Thanks

EPC = electronic pressure control solenoid. It controls hydraulic pressures within the transmission via the car's computer. A problem child in these transmissions... NOT long lived on average. There is a ton of info on here if you care to take the time to read up on it... but it rather sounds like you will have a shop do what you decide do anyway? (which is fine).

 

[BrooklynBay]

A lot of times when there is a temperature related issue, it points to the valve body gaskets. The gasket usually blows out near the EPC solenoid. The low frequency vibrations emitted from the EPC solenoid cause the bolts to get loose, then the pressure starts to flake apart the gasket. Drop the pan, inspect the gasket, and check the torque of the valve body bolts. Connect a 0-300 PSI pressure gauge on the EPC port to test the pressure before starting this, then compare the pressure after you do this. It should be a little higher unless the EPC is starting to go bad as Glacier991 previously suggested.

 

[bud4ya]

Thanks for the reply sounds like I will replace both depending on the cost of each.

A lot of times when there is a temperature related issue, it points to the valve body gaskets. The gasket usually blows out near the EPC solenoid. The low frequency vibrations emitted from the EPC solenoid cause the bolts to get loose, then the pressure starts to flake apart the gasket. Drop the pan, inspect the gasket, and check the torque of the valve body bolts. Connect a 0-300 PSI pressure gauge on the EPC port to test the pressure before starting this, then compare the pressure after you do this. It should be a little higher unless the EPC is starting to go bad as Glacier991 previously suggested.

 

[Glacier991]

I was reading this thread again and it struck me that you don';t have a 5R55E since you have a V-8 you have a 4R70W. Different tranny. I'll reanswer your question this evening when I have a little more time - this time I'll be talking about the right tranny.

 

[bud4ya]

I look forward to your response. Thanks for taking the time

I was reading this thread again and it struck me that you don';t have a 5R55E since you have a V-8 you have a 4R70W. Different tranny. I'll reanswer your question this evening when I have a little more time - this time I'll be talking about the right tranny.

 

[bud4ya]

Just another update. It acted up all the way to work like I described. I let it sit the whole day till 5:00. Let it warm up 15 mins then got in and drove and it is back to shifting fine.

I was reading this thread again and it struck me that you don';t have a 5R55E since you have a V-8 you have a 4R70W. Different tranny. I'll reanswer your question this evening when I have a little more time - this time I'll be talking about the right tranny.

 

[Glacier991]

Ok... let's start by looking at what causes the 1-2 shift in the 4R70W to start with.... and then we can work from there. The fact you have an intermittent is actually a good thing because it rules out certain mechanical failures that once happened would not ever be right again without a rebuild.

In the A4LD and 4R44 and 5R44 series the 1-2 shift is caused by applying the intermediate band (in the 5R55 2nd gear is nothing more than an overdriven 1st gear). But you have the 4R70W. It gets 2nd gear by applying the intermediate clutch, located directly behind the pump and using the case as its housing. Your intermediate clutch is applying late, sometimes. Why? is the question.

If you did not get a 1-2 shift at all or if it was always screwed up we could be looking at a myriad of things, but the fact that it works fine *sometimes* means we can look past those things... So let's look at the hydraulics, as it is likely something somewhere in the hydraulic circuitry not always supplying the force to apply the intermediate piston and locking up the intermediate clutch and effecting the 1-2 shift.

First off, this transmission has 2 shift solenoids, housed together on the main control unit (valve body) and easy to replace by merely dropping the pan. When the PCM sesnse the conditions are right for the 1-2 shift (more on this later) it turns off the SS11 solenoid off, and the SS2 will (or should) remain off. By turning off the SS1 solenoid, pressure on one side of the 1-2 shift valve is removed and so the other side overpowers it and it starts to move. The movement allows fluid to start to energize the Intermediate clutch circuit. This circuit applies the intermediate clutch and causes the 1-2 accumulator to become active. Important in all this is that there is a check ball involved which seals the circuit and allows it to pressurize. A stuck or sticky check ball wouldnot allow the circuit to pressurize, and you would not have a intermediate engagement due to that fact. There is also fluid flow to the OD servo regulator, but I think for our analysis at this point we can put that in the back of our minds.

One of several things is likely happening. First, the PCM is not getting the inputs it needs to command the shift. These inputs come from the output shaft speed sensor (as well as others but that is the main one) for this shift. Possible intermittent OSS problem? On the list of possibles. Cost to replace? $20 plus labor, on the outside of the case near the rear.

If the PCM is telling SS1 to turn off, is SS1 hanging up? Another possible. Cost to replace? A bath in ATF when you remove the pan and about $35 for the solenoid pair. Add a pan drain plug.

If the PCM is doing its job, and SS1 is doing its job, is the 1-2 shift valve sticking in the VB? Is the 1-2 accumulator causing a problem? Is the check ball grunged up in the main control unit and not seating causing a problem? The 1-2 accumulator is under the main control unit, and if you remove it SHOULD be replaced for under $10. The main control unit should be gone through to check for any debris or other problems that might cause either the 1-2 shift valve to hang up, or the #8 checkball not to seat properly. Add new gaskets when you replace and torque it properly using an inch lb torque wrench.

Obviously these things MAY not fix your problem, but these are the items that I sense are involved, either ONE of them, or a combination. Good luck.

 

[bud4ya]

Glacier wow you really know you stuff. Thanks so much. This is what I come up with from reading your post of the possible items causing the prob. Can you review the list and let me know if I read it correctly?

1) 2 Solenoids (If this is it replace both solenoids?)

2) Valve Body (If this is it replace Valve Body?)

3) PCM not getting command to shift from speed sensor (If this is it replace speed sensor?)

4) PCM is telling SS1 to turn off and SS1 is hanging up. Is SS2 and solenoid? (If this is it replace PCM?)

5)1st to 2nd shift valve is sticking (If this is it replace shift valve?)

6) Check ball grunged up in main control unit (If this clean up control unit?)

7) Control Unit (If this is it replace Control unit?)

If some of these are the same item let me know.

Thanks again I REALLY appreciate this

Ok... let's start by looking at what causes the 1-2 shift in the 4R70W to start with.... and then we can work from there. The fact you have an intermittent is actually a good thing because it rules out certain mechanical failures that once happened would not ever be right again without a rebuild.

In the A4LD and 4R44 and 5R44 series the 1-2 shift is caused by applying the intermediate band (in the 5R55 2nd gear is nothing more than an overdriven 1st gear). But you have the 4R70W. It gets 2nd gear by applying the intermediate clutch, located directly behind the pump and using the case as its housing. Your intermediate clutch is applying late, sometimes. Why? is the question.

If you did not get a 1-2 shift at all or if it was always screwed up we could be looking at a myriad of things, but the fact that it works fine *sometimes* means we can look past those things... So let's look at the hydraulics, as it is likely something somewhere in the hydraulic circuitry not always supplying the force to apply the intermediate piston and locking up the intermediate clutch and effecting the 1-2 shift.

First off, this transmission has 2 shift solenoids, housed together on the main control unit (valve body) and easy to replace by merely dropping the pan. When the PCM sesnse the conditions are right for the 1-2 shift (more on this later) it turns off the SS1 solenoid off, and the SS2 will (or should remain off). By turning off the SS1 solenoid, pressure on one side of the 1-2 shift valve is removed and so the other side overpowers it and it starts to move. The movement allows fluid to start to energize the Intermediate clutch circuit. This circuit applies the intermediate clutch and causes the 1-2 accumulator to become active. Important in all this is that there is a check ball involved which seals the circuit and allows it to pressurize. A stuck or sticky check ball wouldnot allow the circuit to pressurize, and you would not have a intermediate engagement due to that fact. There is also fluid flow to the OD servo regulator, but I think for our analysis at this point we can put that in the back of our minds.

One of several things is likely happening. First, the PCM is not getting the inputs it needs to command the shift. These inputs come from the output shaft speed sensor (as well as others but that is the main one) for this shift. Possible intermittent OSS problem? On the list of possibles. Cost to replace? $20 plus labor, on the outside of the case near the rear.

If the PCM is telling SS1 to turn off, is SS1 hanging up? Another possible. Cost to replace? A bath in ATF when you remove the pan and about $35 for the solenoid pair. Add a pan drain plug.

If the PCM is doing its job, and SSS1 is doing its job, is the 1-2 shift valve sticking in the VB? Is the 1-2 accumulator causing a problem? Is the check ball grunged up in the main control unit and not seating causing a problem? The 1-2 accumulator is under the main control unit, and if you remove it SHOULD be replaced for under $10. The main control unit should be gone through to check for any debris or other problems that might cause either the 1-2 shift valve to hang up, or the #8 checkball not to seat properly. Add new gaskets when you replace and torque it properly using an inch lb torque wrench.

Obviously these things MAY not fix your problem, but these are the items that I sense are involved, either ONE of them, or a combination. Good luck.

 

[BrooklynBay]

Unless a valve body is badly warped, or scoured up, it could be rebuilt.

 

[Glacier991]

Well.... in order of ease, check out the OSS and the wiring to it. While I am doubtful it is the root cause, you can replace it without getting messy with ATF removing the pan. You'll be out about $20. It *could* fix your problem. (though as I said I am a little doubtful this IS the problem).

Next up, I'd remove the pan and remove the valve body. While I had it out I would replace the 1-2 accumulator, which lives in the case under the valve body. Cost ya about $10. Then I would inspect the 1-2 shift valve for freedom of movement or any binding. I'd also remove the separator plate and visually make sure no check balls were gunked up or in some way not able to seat due to debris, etc.

If I found nothing at all wrong, I might be tempted to just go ahead and buy the shift solenoids (they come as one unit, with 2 solenoids in it) and replace them at this time. That will set you back about $35.

Then I'd add new gaskets and reinstall the valve body and properly torque it using an inch pound torque wrench.

That would pretty much cover the things I discussed above.

 

[bud4ya]

Excately what I needed. I will get those things looked at in the next week or two and post my results.

Again Thanks

Thanks To Everyone

Well.... in order of ease, check out the OSS and the wiring to it. While I am doubtful it is the root cause, you can replace it without getting messy with ATF removing the pan. You'll be out about $20. It *could* fix your problem. (though as I said I am a little doubtful this IS the problem).

Next up, I'd remove the pan and remove the valve body. While I had it out I would replace the 1-2 accumulator, which lives in the case under the valve body. Cost ya about $10. Then I would inspect the 1-2 shift valve for freedom of movement or any binding. I'd also remove the separator plate and visually make sure no check balls were gunked up or in some way not able to seat due to debris, etc.

If I found nothing at all wrong, I might be tempted to just go ahead and buy the shift solenoids (they come as one unit, with 2 solenoids in it) and replace them at this time. That will set you back about $35.

Then I'd add new gaskets and reinstall the valve body and properly torque it using an inch pound torque wrench.

That would pretty much cover the things I discussed above.

 

[Varsity]

Any updates? My trans surged to about 2500 RPM before shifting into 2nd but everything else seems fine. Sounds ALOT like my problem.

 

[rhinder]

I'm having the same issues. I've replaced transmission and a week later its doing the same thing. Checked cooler lines and both coolers there clear. In process of checking all wiring to transmission. It's starting to look like the problem is the computer is the issue. But it only does it after driving long distance.