Trans line pressure question
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Trans line pressure question
Hey guys, I'm working on a 96 powerstroke with an auto trans. . . E40 D I think? Going through the service manual. . .it says line pressure at idle is supposed to be between 75-99 psi in manual 1 and reverse. And between I think 55-65 in all other selections. When warmed up. . . manual 1 and reverse the pressure imediately is at 150 and quickly climbs to 180-200. When warmed up it nearly kills the engine every time these gears are selected. it feels like the torque converted is locking up. . . When its real warm it will almost every time kill the motor. all other idlepressures in the other gears are 100 psi. So everything seems high, and especially so, where I'm having the problem. If it doesn't kill the motor. . . it bogs down real hard for a few seconds then comes back to normal. Any thoughts? Thanks so much.
Timmy
Timmy
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From: Belair md
all "limp mode" means is the pcm saw something it did not like, whether it was a clutch slipping, the tc slipping, or a loss of signal. when that happens the pcm reverts to a default program which maxs line pressure to prevent any further damage to the internals until you get to a dealer. your abnormally high pressure readings are why mark suggested this theory.
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all "limp mode" means is the pcm saw something it did not like, whether it was a clutch slipping, the tc slipping, or a loss of signal. when that happens the pcm reverts to a default program which maxs line pressure to prevent any further damage to the internals until you get to a dealer. your abnormally high pressure readings are why mark suggested this theory.
If this is the case. . . there certainly should be a code then correct? The pressure is controlled by that "proportioning valve" for lack of better words. . . right? Its just wierd how only in manual first and reverse the pressure gets so high. And its so consistant how immediately after putting in either of those two gears. . . its instant 150 psi and quickly climbs to nearly 200 psi. Hmm. . .guess I'm just throwing out thoughts, just want to learn the systems more. Thanks.
Timmy
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From: Belair md
the pressure is controlled by the pcm, it ground the 12 volt circuit that travels through the electronic pressure control solonoid. it varies pressure from roughly 5-12 volts depending on how much pressure the pcm feels the tranny needs based on gear selection and torque. the higher the voltage the lower the pressure. as far as why only those 2 gears have high pressure i cannot tell you off the top of my head. i would have to go get the service manuals out and its a little late for that tongiht....lol
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Pressure from the transmission pump activates the torque converter clutch. If the trans has a high pressure demand at idle there isn't enough pressure left to send to the torque converter. The converter will operate at zero pressure as long is it is filled with ATF. The torque converter clutch uses pressure to hold it off, and if that pressure isn't present the clutch can drag, putting a lot of load on the engine at idle.
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So two things. . . one i'm not getting any indication from the trans as far as codes. When AE asks me if I want all systems codes. . . i click all. . . and it loads 1 of 1. . . enhanced powertrain. Is that where the tranny codes will be stored? None found so far. Two. . . What is "electronic pressure control" and "electronic pressure control volts" in the AE? Is that for the back pressure valve or is that for the trans? Next. . . the overdrive switch appears to be doing nothing. When pressed. . . the light comes on but i get no indication from the coast clutch solenoid or torque converter clutch that its actually working. I have more to update. . . but I need to go test a few more things first.
Timmy
Timmy
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What is "torque converter clutch ctrl internal circuit mon" and "torque converter clutch-modulated?" Neither of them have changed at all during operation. The TCIL shows on or off on AE. . . but the overdrive cancle/hold switch whichI assume is the same thing. . . does nothing. The switch operates fine on the road. . . coast clutch does come on and overdrive does come off. trans fluid temp volts is around 1.39 warmed up. . . and at this temp is acting up in manual 1 and reverse almost 100% Any thoughts? Thanks.
Timmy
Timmy
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