E4OD Torque Converter Lock Up Behavior
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5th Wheeling
Joined: Mar 2021
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E4OD Torque Converter Lock Up Behavior
Hey guys, I'm hoping Mark Kovalsky sees this as I know he is the transmission guru here. My truck is a 1990 F250 with the E4OD/460.
This is more my curiosity than anything, but does the E4OD unlock the torque converter just before the shift to overdrive? I've always noticed a smaller RPM drop after the shift to overdrive, which I assume is the torque converter clutch locking up, but since it typically locks up right after it shifts to 3rd, that would indicate that it unlocked before the shift to overdrive. If this is the case, what would be the rationale for it? Would the shift to overdrive be harsher with the converter locked vs unlocked? Thank you!
This is more my curiosity than anything, but does the E4OD unlock the torque converter just before the shift to overdrive? I've always noticed a smaller RPM drop after the shift to overdrive, which I assume is the torque converter clutch locking up, but since it typically locks up right after it shifts to 3rd, that would indicate that it unlocked before the shift to overdrive. If this is the case, what would be the rationale for it? Would the shift to overdrive be harsher with the converter locked vs unlocked? Thank you!
Logistics Pro
Joined: Aug 2014
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See your next question.
You may notice when the vehicle is cold and engine running less than a few minutes that the converter does not loc until trans is at temperature.
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5th Wheeling
Joined: Mar 2021
Posts: 26
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That makes sense, and is what I suspected. Thank you, wwhite!
yes, I have noticed that about the converter being unlocked til the system warms up. I know there’s a sensor on the solenoid pack that reads the transmission fluid temp and that is an input into the computer’s decision to lock. Makes sense!
yes, I have noticed that about the converter being unlocked til the system warms up. I know there’s a sensor on the solenoid pack that reads the transmission fluid temp and that is an input into the computer’s decision to lock. Makes sense!
Tuned
Joined: Jan 2015
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Related question to continue the information flow....I got tired of hard shifts and installed a switch to disable the TCC solenoid. Off = No torque convertor clutch, On = Automatic/EEC controlled clutch. I tend to leave it Off when tooling around town since most driving is <50-55 MPH, then turn it On when I hit the highway. If I leave it On in town the shift from 1->2 and 2->3 can be an impossible-to-ignore kick. There's still a little bump when overdrive kicks in, but not much. Would this roughness be considered normal, or is there something that's maybe not disengaging the clutch during the shift like it should (if I read the above comments correctly)?
Logistics Pro
Joined: Aug 2014
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If you have hard shifts, there is something else going on, or there is a shift kit installed.
Does your truck stall if you leave the switch on when you come to a stop?
Does your truck stall if you leave the switch on when you come to a stop?
Tuned
Joined: Jan 2015
Posts: 476
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No, no stalling.
No shift kit. It's a remanufactured unit I put in several years ago. Replaced the MLPS at the same time. Also cleaned the connectors well and made a heat shield to protect them before plugging them back in.
I've also replaced the capacitors in my EEC. I do have a second one that's also been repaired that way. Might need to swap that in to see what happens.
I did have an occasional issue that started sometime last year where it would lurch and die when I put it into reverse, but this hard shift feeling has been there as long as I can remember. Ended up breaking the shift tube on the column trying to ensure I was getting full-range shifting. After I replaced the column parts and the shift cable it's back to brand new. I didn't take it apart, but the old cable must've unwound in the tube or something because it was really difficult compared to the new cable. So, note to others, if your shifter seems harder than it should be, and won't go into Reverse or Park properly, maybe your cable is bad.
Anyway, no stalling, and no other obvious transmission issues otherwise.
No shift kit. It's a remanufactured unit I put in several years ago. Replaced the MLPS at the same time. Also cleaned the connectors well and made a heat shield to protect them before plugging them back in.
I've also replaced the capacitors in my EEC. I do have a second one that's also been repaired that way. Might need to swap that in to see what happens.
I did have an occasional issue that started sometime last year where it would lurch and die when I put it into reverse, but this hard shift feeling has been there as long as I can remember. Ended up breaking the shift tube on the column trying to ensure I was getting full-range shifting. After I replaced the column parts and the shift cable it's back to brand new. I didn't take it apart, but the old cable must've unwound in the tube or something because it was really difficult compared to the new cable. So, note to others, if your shifter seems harder than it should be, and won't go into Reverse or Park properly, maybe your cable is bad.
Anyway, no stalling, and no other obvious transmission issues otherwise.
Logistics Pro
Joined: Aug 2014
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Maybe you have the incorrect computer.
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Frmr Ford Trans Engr
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Related question to continue the information flow....I got tired of hard shifts and installed a switch to disable the TCC solenoid. Off = No torque convertor clutch, On = Automatic/EEC controlled clutch. I tend to leave it Off when tooling around town since most driving is <50-55 MPH, then turn it On when I hit the highway. If I leave it On in town the shift from 1->2 and 2->3 can be an impossible-to-ignore kick. There's still a little bump when overdrive kicks in, but not much. Would this roughness be considered normal, or is there something that's maybe not disengaging the clutch during the shift like it should (if I read the above comments correctly)?
The only way that I can think of to keep this from happening is to not disable the converter clutch. Otherwise, you'll just have to live with it.
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What I think is happening is that when the converter is disabled the EEC knows that and sets codes. You should have codes for excessive slip and a TCC solenoid electrical fault. Either one of those codes will put the trans in FMEM (Failure Mode Effects Management.) Part of the FMEM is to set line pressure higher than normal to prevent transmission damage when things are not right.
The only way that I can think of to keep this from happening is to not disable the converter clutch. Otherwise, you'll just have to live with it.
The only way that I can think of to keep this from happening is to not disable the converter clutch. Otherwise, you'll just have to live with it.
Tuned
Joined: Jan 2015
Posts: 476
Likes: 93
I had run codes a few weeks ago to see about an engine hiccup that happens/is mostly noticeable when it's idling. There was one for the EGR and another I don't remember, but no transmission codes. I haven't found the time to get back on that problem yet.
I had heard that this switch might cause some code events, but I've never seen any codes about the transmission in the handful of times I've checked for them over the last few years.
Also, when I replaced the transmission a rebuilt torque converter came with it so I replaced both at the same time.
Is there somewhere that I can find a write-up of the theory of operation of the E4OD? And it would be nice to have the same for the PCM/EEC in these trucks. It would be interesting to understand what's really happening, and it might help with my occasional insomnia. lol
EDIT: Both computers are the same - HOG0 (F4TF-12A650-AAA). One was original, other was a purchase.
I had heard that this switch might cause some code events, but I've never seen any codes about the transmission in the handful of times I've checked for them over the last few years.
Also, when I replaced the transmission a rebuilt torque converter came with it so I replaced both at the same time.
Is there somewhere that I can find a write-up of the theory of operation of the E4OD? And it would be nice to have the same for the PCM/EEC in these trucks. It would be interesting to understand what's really happening, and it might help with my occasional insomnia. lol
EDIT: Both computers are the same - HOG0 (F4TF-12A650-AAA). One was original, other was a purchase.
Logistics Pro
Joined: Aug 2014
Posts: 3,570
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Is there somewhere that I can find a write-up of the theory of operation of the E4OD? And it would be nice to have the same for the PCM/EEC in these trucks. It would be interesting to understand what's really happening, and it might help with my occasional insomnia. lol
pm me for everything I know.
for E4OD information with exactly how it works, google the LHBH1 document , it’s all in there.
SD is easier for me, not so much the MAF.
Cargo Master
Joined: Mar 2007
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FYI. I am almost certain if the transmission was rebuilt the rebuilder put in a higher than stock pressure regulator for the line pressure. I believe it bumps up the pressure by about 20 psi. I know my E4OD will not go lower than 90 psi. Try and find a stock spring and you can't. Well, I could not. There are plenty of springs that are designed to raise the pressures slightly and I suspect all pumps and transmissions use that when they are being rebuilt.
Just a thought and worth researching.
Just a thought and worth researching.
Tuned
Joined: Jan 2015
Posts: 476
Likes: 93
FYI. I am almost certain if the transmission was rebuilt the rebuilder put in a higher than stock pressure regulator for the line pressure. I believe it bumps up the pressure by about 20 psi. I know my E4OD will not go lower than 90 psi. Try and find a stock spring and you can't. Well, I could not. There are plenty of springs that are designed to raise the pressures slightly and I suspect all pumps and transmissions use that when they are being rebuilt.
Just a thought and worth researching.
Just a thought and worth researching.