Not dropping into overdrive
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Freshman User
Joined: Aug 2011
Posts: 28
Likes: 0
Not dropping into overdrive
Howdy, looking for some feedback, have 95 250heavy 7.3 turbo stroker, : so when accelerating at about 80km it won't drop into overdrive and the od light on the gear shift flashes, then slowing down tranny shifts harder until I stop and reset the dcts , code p1728. I can drive around at about 60 km and get no codes at all only when trying to accelerate at highway speed. Replaced speed sensor no change , had a tranny cooler replaced also as it blew and fluid is good. It is also suoerchipped and currently in stock setting.
Any feedback is awesome!!
Any feedback is awesome!!
Fleet Mechanic
Joined: Aug 2007
Posts: 1,508
Likes: 2
From: The boonies by Dallas OR
Based on your description that it only sets codes when you accelerate at high speed it sounds like the overdrive clutch is slipping.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,712
Likes: 2,631
From: SE Florida
The PCM can only check for slippage when the trans is in overdrive. That does not mean it is the overdrive clutch slipping.
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Butt-Head
Joined: Apr 2004
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From: Reed Point, MT
The unfortunate thing about the 95-97 trucks vs. the 99-up trucks is that the PCM is unable to determine WHAT is actually causing the slip. Since there is no turbine speed sensor on the E4OD, the PCM cannot distinguish between a converter clutch failure or any of the clutches applied to "make" the gear.
My only concern here is that you have 3rd gear and (depending on your PCM calibration) torque converter clutch apply. If you simply do not have 4th gear, then I would be setting out to get a few more diagnostics done to figure out what's happening here. The only difference between 3rd and 4th is the apply of the overdrive clutch. If you have TCC apply in 3rd and then no fourth gear (be sure it's commanded based on shift solenoid status), then I'd be looking elsewhere for your slip (or lack of OD clutch apply).
My only concern here is that you have 3rd gear and (depending on your PCM calibration) torque converter clutch apply. If you simply do not have 4th gear, then I would be setting out to get a few more diagnostics done to figure out what's happening here. The only difference between 3rd and 4th is the apply of the overdrive clutch. If you have TCC apply in 3rd and then no fourth gear (be sure it's commanded based on shift solenoid status), then I'd be looking elsewhere for your slip (or lack of OD clutch apply).
Fleet Mechanic
Joined: Aug 2007
Posts: 1,508
Likes: 2
From: The boonies by Dallas OR
It doesn't check in direct? If not, why?
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,712
Likes: 2,631
From: SE Florida
Because the torque converter needs to be locked for a certain amount of time before checking. Most of the time it isn't locked long enough before shifting to overdrive. So the software was written to only check in overdrive when the torque converter is locked.
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Freshman User
Joined: Aug 2011
Posts: 28
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Well, awesome feedback... Anyways I am now leaking tran fluid from below the front of the tranny where the torque convertor is. It's going in shop soon but the leak is telling that it's the torque convertor and or the seal at the tcc...
Post Fiend
Joined: Dec 2010
Posts: 10,121
Likes: 3
From: Orrville, Ohio
Sounds like it needs to go in the shop either way.
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Freshman User
Joined: Aug 2011
Posts: 28
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So it was in shop and the end result is either a new torque convertor or rebuild tranny, there saying that with 300k on tranny the tc could just be a bandaid on future problems and why spend the money on a new tc and labour when I should just put in a rebuild ..,,, not sure what to do
