Transmissiondude
New Member
- Joined
- August 6, 2014
- Messages
- 7
- Reaction score
- 0
- City, State
- Houston, TX
- Year, Model & Trim Level
- 2005 Explorer Sport Trac
I have a 2005 Explorer Sport Trac With 4.0L Engine & 5r55E.
I was having problems with the trans intermittently losing reverse when hot, and flaring on the 2-3 shift.
I pulled the trans to rebuild it and find that NOTHING inside the trans is burned, or damaged. I completely rebuilt the transmission to include lip seals, all clutches, all 3 bands, O-rings, gaskets, seals, servos, etc; I even installed a Trans-Go shift correction package. I checked the servo bores in the case very carefully to be sure there was no leakage at the case. There is no noticeable wear in the servo bores.
After rebuild the trans was still doing the same thing. When cold it would work okay, but when hot the trans would feel like it was not wanting to go into reverse and flaring on the 2-3 shift, and also slipping in any gear once it was hot.
I replaced the valve body with a used unit as it was available and I needed to see if I could get it running correctly. Reverse issue seems to be fixed however the trans will now slip in all gears when hot under heavy throttle. Light throttle it will hold all gears just fine. Works perfectly when cold. Not setting any codes & no O/D light flashing.
I hooked up a pressure gauge and have 225 @ idle in Reverse and pressure rises rapidly if you apply the gas. My gauge only goes to 300 and it will peg the gauge in reverse @ 1800+ RPM. In park & neutral I have 75 PSI @ idle. In Drive I have 125 PSI @ idle. Here's the odd part-the pressure WILL NOT rise when in D and I give it gas. It will stay steady at 125 until it shifts to 2nd then it drops to 75, then quickly rises back up again to 125 PSI on the 2-3 shift. However, in NO FORWARD gears will it exceed 125.
I then hooked up a voltmeter to the signal wire to the EPC. With the harness still attached to the transmission I could now see what the voltage to the EPC was doing. In reverse @ idle it was 1.9V pressure @ 225. Give it gas, and voltage drops lower to 1.4V & pressure rises very rapidly to 300+PSI. In drive @ idle voltage is 2.9V pressure @ 125 PSI. If I power brake it (press brakes to keep rear tires from spinning/vehicle moving-pressure STAYS @ 125 PSI but voltage actually increases. In my mind, this is a computer problem because the TCM should be commanding LOWER voltage to the EPC to raise pressure. But this is not happening. I have no voltage drop on acceleration nor does the pressure rise. Of course the vehicle runs normally under light throttle but once you stomp the pedal it will slip in all gears. I believe the problem is the TCM because the computer is not commanding a line pressure increase. Your thoughts?
Any other tests I can try? I'm doing the mod to bypass the trans cooler thermostat tomorrow just to see if it is a temperature related issue. However my tests are showing me that I have a pressure problem so I doubt this latest mod will help.
Lot of reading, but I'm trying to be as thorough as possible.
I was having problems with the trans intermittently losing reverse when hot, and flaring on the 2-3 shift.
I pulled the trans to rebuild it and find that NOTHING inside the trans is burned, or damaged. I completely rebuilt the transmission to include lip seals, all clutches, all 3 bands, O-rings, gaskets, seals, servos, etc; I even installed a Trans-Go shift correction package. I checked the servo bores in the case very carefully to be sure there was no leakage at the case. There is no noticeable wear in the servo bores.
After rebuild the trans was still doing the same thing. When cold it would work okay, but when hot the trans would feel like it was not wanting to go into reverse and flaring on the 2-3 shift, and also slipping in any gear once it was hot.
I replaced the valve body with a used unit as it was available and I needed to see if I could get it running correctly. Reverse issue seems to be fixed however the trans will now slip in all gears when hot under heavy throttle. Light throttle it will hold all gears just fine. Works perfectly when cold. Not setting any codes & no O/D light flashing.
I hooked up a pressure gauge and have 225 @ idle in Reverse and pressure rises rapidly if you apply the gas. My gauge only goes to 300 and it will peg the gauge in reverse @ 1800+ RPM. In park & neutral I have 75 PSI @ idle. In Drive I have 125 PSI @ idle. Here's the odd part-the pressure WILL NOT rise when in D and I give it gas. It will stay steady at 125 until it shifts to 2nd then it drops to 75, then quickly rises back up again to 125 PSI on the 2-3 shift. However, in NO FORWARD gears will it exceed 125.
I then hooked up a voltmeter to the signal wire to the EPC. With the harness still attached to the transmission I could now see what the voltage to the EPC was doing. In reverse @ idle it was 1.9V pressure @ 225. Give it gas, and voltage drops lower to 1.4V & pressure rises very rapidly to 300+PSI. In drive @ idle voltage is 2.9V pressure @ 125 PSI. If I power brake it (press brakes to keep rear tires from spinning/vehicle moving-pressure STAYS @ 125 PSI but voltage actually increases. In my mind, this is a computer problem because the TCM should be commanding LOWER voltage to the EPC to raise pressure. But this is not happening. I have no voltage drop on acceleration nor does the pressure rise. Of course the vehicle runs normally under light throttle but once you stomp the pedal it will slip in all gears. I believe the problem is the TCM because the computer is not commanding a line pressure increase. Your thoughts?
Any other tests I can try? I'm doing the mod to bypass the trans cooler thermostat tomorrow just to see if it is a temperature related issue. However my tests are showing me that I have a pressure problem so I doubt this latest mod will help.
Lot of reading, but I'm trying to be as thorough as possible.