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Deoxyrybose

Edge Member
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About Deoxyrybose

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    New Member

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  • Region
    U.S. Northeast
  • Current Vehicle
    Lincoln MKX

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  1. Deoxyrybose

    Hard Shifting

    Service history? I wish I could give it to you lol Like I said, I bought it at 200k miles from a used car dealer. I did plugs recently (about 2k miles ago). I plan to do a drain and fill soon, I can report back fluid condition. Hopefully that's the issue, but I'm a bit skeptical. Easier to start with fluids though, good suggestion.
  2. Deoxyrybose

    Hard Shifting

    Nobody...? I have some wiring diagrams. I can locate the signal wires on both the throttle position sensors, signals on the 3 accelerator pedal position sensors, and the signals from the input and output shaft speed sensors (the ones in the trans that always go bad). The goal is to view the signals for any obvious issues, and try to view each during the bad shifting events. Today it was 30 degrees this morning, and the entire length of my street it wouldn't upshift. I'm going to double check fluid, but I feel like this is an electronic issue.
  3. Deoxyrybose

    Hard Shifting

    Hey all, 2008 MKX and since i've bought it at 200k miles (currently 213k) the transmission does some specific things. It shifts HARD when going from D to R consistently. I don't know enough about the inner workings of transmissions but I'd wager there's something special about that particular shift because it's always the hardest one. Sometimes it'll slam when downshifting up a steep hill as well... give it more gas and more and more up the hill until it downshifts, and BOOM. The third condition I've noticed is if you slow down (like taking a turn at an intersection), when you get on the gas again it will buck (this may be a downshift?). Finally, rarely it will fail to upshift completely. You'll ride out the entire gear, sometimes hang out in it for a while, and then it'll find the next gear. It otherwise is normal if you make no sudden pedal movements and drive it smoothly. I've heard that the input/output speed sensors can do this, but I have never had the odometer read "- - - - - - " or gone into limp mode. I also heard that the electronic throttle body could fail, causing incorrect throttle positions signals, thus bad estimated torque values in the ECM, and hard shifts. Then there's the whole "adaptive learning" portion of the trans, and of course failing shift/pressure solenoids. My question is, does anyone know how to diagnose or at least rule out some of these things? I just bought an automotive oscilloscope so I'm able to read the 'front door' sensor data from any of the above. Interested in what I should attack first, or any information at all that can lead me in the right direction without blindly replacing parts 😛
  4. Deoxyrybose

    AWD to FWD Conversion

    You're correct. If you've gone that far, you might as well change it. But then I'm in it for the cost of a new PTU, and if the seals go, as SO many have, it's more hastle than it's worth to replace seals. My idea is a lot of work, I understand that, I was just looking for a wits-end alternative to dealing with poor engineering. My PTU is currently leaking out the tail shaft seal, and the passenger side seal (or at least it seems that way, maybe it's coming from above?) Another alternative I may take is to just let it leak but keep filling it. Always fresh fluid, and I don't have to tear half the car apart and use special seal drivers/pullers to fix it. The problems add up and I start to wonder if it's worth keeping. The slam shifting has blown my engine mounts and cracked the old rusted exhaust. I tried replacing the mount, but snapped the first bolt right off at the bottom of the cat getting the Y pipe off. That's when I noticed the PTU leaking. Money pit.
  5. Deoxyrybose

    AWD to FWD Conversion

    I'm sure this has been covered 100 times, but the threads I've found don't have satisfying answers. What are your thoughts on an AWD to FWD conversion for a failing or leaking PTU? I simply don't have $1,500 to drop on a repair to literally have it happen again, which we all know is the case. Physically, this is my idea. Starting at the back, you could remove both axle shafts, the rear diff, the driveshaft and stop there. The problem with that method is eventually when all the fluid leaks out, the friction will cause the gears to fracture within the PTU, and honestly it's a crap shoot if it breaks the transaxle-side gear or one of the others. Potentially it could resolve itself (once it breaks, if the transaxle side continues to spin in the case, you've won the lotto, you're free!) but more realistically it could lock up and keep the transmission from spinning, and toast the transaxle. Alternatively, if you were to remove all of the above components, and in addition the PTU as well... then pull one or all of the gears out of it and then reinstall it... you would just have the transaxle shaft spinning alone inside the PTU case. Mechanically this is sound, no danger to other components. Remember that the whole AWD system spins idling at all times until the rear dif solenoid engages it and puts an actual load on it. But, this is where the problems come in though... the ECU will likely notice the lack of input from the AWD system. How? I'm not sure. Maybe the Rear diff solenoid would have to remain hooked up to some extent, just so the ECU is happy it can ground the circuit properly at will? How would the ECU know we've disconnected the system? The tires should all spin at the same rate for a given speed, so RPM signal would likely not be valuable feedback for if AWD is active or not. I appologize for the rant, but I'm interested in salvaging the remainder of these wonder vehicles, despite the ONE glaring flaw of the PTU. So I guess one bit of homework is how does the Edge even differentiate the torque front to rear? If the AWD system right up until the rear diff solenoid is always active (spinning), and it's mechanically, permanently geared, to the transaxle, how does the car "split" torque? Some cars that have a center diff can split torque 20/80, 60/40, etc I don't see that happening here because there's no center diff. So would this even affect the driveability of the vehicle, and will this set check engine lights? (and how?). Thanks in advance, let the conversation begin!
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