99 SOHC 2WD 5R55E Upshift too quickly

[AtlantaViking]

Hi all. I seem to spend more time on this site and am always amazed at the folks on here. Very helpful bunch I have to say.

My Ex has 173K on it, still the factory tranny, no major issues with it. No codes or anything. What it has been doing over the last, maybe 25K miles in normal driving it doesn't seem to want to hold a gear very long and upshifts to a higher one. Once in the higher gear - it wants to stay there even when it starts to get hillier and I would think it would downshift and I actually need it to. If I remove my foot from the accelerator and then get back into it - it finds the appropriate lower gear but unless I stay in the go pedal it will upshift pretty quick.

Anyone else experience this? Any fixes? I've looked through so many posts but haven't found anything that seems to be similar to what I'm running into.

Thanks a bunch!

 

[PopRichie77]

Never heard of this problem before but I guess anything is possible. Here are a couple things which might and I say might cause this problem. Dirty or bad MAF sensor, TP sensor, Output shaft sensor, or bad PCM.

 

[2000StreetRod]

Good advice

Never heard of this problem before but I guess anything is possible. Here are a couple things which might and I say might cause this problem. Dirty or bad MAF sensor, TP sensor, Output shaft sensor, or bad PCM.

I assume that you have checked the fluid level.

Ford Explorer - Ranger TPS Test Procedure

MAF Sensor Test Procedure

You may also want to check the IAT sensor and the ECT sensor. If your sensors check out then you probably need to perform a line pressure test. Do the symptoms worsen after the transmission warms up? You could have low line pressure due to a blown out valve body gasket.

 

[AtlantaViking]

Some Good Thoughts

Thanks folks, I was focused maybe too much on the tranny itself, I never really though about the TPS or the MAF sensors primarily because the engine itself is as strong as it ever was and has no indications that it is running out of tune.

The fluid level is good, and I haven't ever re-torqued the OD band so that is where I was thinking, but I may walk the sensors and see.

And yes, it seems to get worse when the truck is completely warmed up. If it were the gasket in the VB, wouldn't it be consistent all the time (warm or cold?).

Thanks again.

 

[2000StreetRod]

. . . And yes, it seems to get worse when the truck is completely warmed up. If it were the gasket in the VB, wouldn't it be consistent all the time (warm or cold?).
Thanks again.

The warmer the ATF the more the gasket leaks. Also, the 5R55E has an internal thermostat that opens the external cooling loop when the torque converter temperature reaches 150 deg F. When the loop opens the line pressure can drop more.

 

[G33k_B0y]

Same Problem Here

I've had the exact same problem here for a couple of years now. I'm almost certain that it's something in the VB. It is definitely far worse when the transmission warms up. It's gotten even worse in the last several months; the transmission has begun to slip horribly. I'm pretty sure it's related. It will only slip at very low RPMs with high torque. However, when the transmission does shift, it still shifts firmly. Glad to hear I'm not the only one with this problem.

 

[AtlantaViking]

G33k_B0y - sorry you have the same issue...FWIW I did check the sensors and they are fine. I'm convinced the issue is in the tranny itself and, like you, am leaning to the valve body. I may just bite the bullet and get a reman VB. With all of the known issues in there, maybe its the EPC or some other item in there related to line pressure. Let me know if you do something that works!

 

[AtlantaViking]

Here's an update: I got the Torque app for my android just to play with and saw that it monitored the gear positions of the tranny. As I was driving I saw that my issue (upshifting too quickly and lugging the engine) corresponds to the tranny shifting from 2nd gear directly to 4th. It never goes into 3rd. It doesn't lag or hunt...just skips 3rd gear.

Does that give anyone an 'AH HAH' moment? Just hoping that someone can clue me in.

 

[PopRichie77]

Strange, there should be a trans code for this problem. Could be a bad PCM. Does manual second work and does it have engine braking?

 

[AtlantaViking]

I guess it could be the PCM but it has never had any dash alerts blinking (OD light) so I don't think thats the culprit. I have a rebuilt valve body on order so we'll see what that does...

Its pretty odd, I tend to drive with a light foot so I'm not usually in the gas heavy, but when I am in a hurry, it will shift through OK. But if I'm easy on it, and start going up a hill by our house (happens all the time) it will jump from 2nd directly to 4th and the rpms drop down to just above idle. I can feel the truck lugging so I take my foot of the accelerator and step back into it (not really heavy but enough) and it will find 3rd.

Its a real head scratcher...

 

[JK080]

I have seen a blown out valvebody gasket right above the EPC solenoid cause it them skip third gear.