Any GM tranny experts out there??

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  • 1911ly

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    I am pretty sure there's a few tranny guys on the list. I hope any way! ;)

    I have a 2007 Buick Terraza that I bought as a fixer upper for my boys first car. It's had a bit of everything wrong with it. I'll probably do a break room thread about "The adventure of my son working on his first car".

    We've had a good time working on it over the summer/fall. We've done a lot to it over the last few months. Everything from replacing the rearend(long story), trouble shooting the ABS brakes (bad front hubs and a wiring harness issue). Load leveling air ride and traction control systems(Broken rearend position switch) . New motor mounts, new brakes. I've got all that sorted out and fixed. Oh and a bad plug wire! Freaken squirrel decide to snack on the one for #3 cylinder. I hate freaken squirrels.

    But to get back on the tranny subject. It feels like it wants to slip a little in first gear then shifts in to second gear very firm. Not every time. And it is more prevalent if you put your foot in it. If you run it threw the gears manually it shifts fine and does not slip at all. So I am thinking the clutches are good.

    It does not throw a error code. From what I am reading on line a P1811 error would be common (PCS bad) but it doesn't throw any codes. I've also read that the accumulators give issues. And a transgo shift kit usually resolves the problem? It's not a expensive fix if so.

    And I changed the trans filter and fluid. It was not the best looking fluid I've ever seen. A bit dark. There wasn't a bunch of crap in the pan or on the magnet. I've seen worse and still run. It's got 149k miles on it. I really don't want to rebuild the transmission. The thing has a lot of dents. And not worth it IMHO.

    So... what do you guys think??
     

    1911ly

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    I'll add that I took it to a tranny shop and they could not find any error codes but the motor mounts were so bad (clunking hard) that he wanted me to replace those first and bring it back.
     

    Woobie

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    It might be electronic. You might be able to do a trans relearn and fix it, but that might be a bit far-fetched. The Allison in my '02 Duramax will go spastic if I roll into the throttle at high speeds, especially with a load. But it's got a crappy tuner. It also has more power than that tranny was designed to handle. Anywho, when this happens, it acts like it is slipping bad in first gear. I go through a trans relearn procedure and I'm on my way.
     

    Woobie

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    I'll add that I took it to a tranny shop and they could not find any error codes but the motor mounts were so bad (clunking hard) that he wanted me to replace those first and bring it back.

    There is a lot of data that the Transmission Control Module tracks, and a good mechanic can look at that data on a Snap-on Modus or similar machine during a driving test and see patterns in the data that are troublesome, but aren't throwing codes.

    Edit: we are nearing the end of my knowledge in this matter, so clearly I am not the expert you are looking for. But I'll help as much as I can.
     

    Brandon

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    My buddies explorer had an issue that sounds *similar* to yours.
    He took it to Midas because there were no codes, they diagnosed a bad shift solenoid. From what I have heard from my friend the issue is gone.
     

    1911ly

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    There is a lot of data that the Transmission Control Module tracks, and a good mechanic can look at that data on a Snap-on Modus or similar machine during a driving test and see patterns in the data that are troublesome, but aren't throwing codes.

    Edit: we are nearing the end of my knowledge in this matter, so clearly I am not the expert you are looking for. But I'll help as much as I can.

    I am not positive on what tool he used but it was the real deal. We drove for a few miles while it was hooked up. He verified the electronics were working. Valves/solenoids were/are switching properly. He wanted to look at it again after the mounts were replaced. Haven't went back as of yet. Thanks for the input. It's appreciated.
     

    1911ly

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    My buddies explorer had an issue that sounds *similar* to yours.
    He took it to Midas because there were no codes, they diagnosed a bad shift solenoid. From what I have heard from my friend the issue is gone.

    The PCS and the 1-2 shift solenoids are fairly common issues. But they seem to be ok.
     

    1911ly

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    And it was doing this before you serviced the transmission, correct?

    Yeah, I was hopeful it might help, but it did not :-(.

    I haven't reset everything it since I replaced the mounts. It's like chicken soup. It can't hurt to try. I'll give that a try. I wish it would throw a code. It would be easier to diagnose.
     

    Woobie

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    I thought you had, just making sure. Sometimes if the transmission is about to call it quits mechanically, symptoms will worsen after a service. But you just ruled that idea out.
     

    1911ly

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    I thought you had, just making sure. Sometimes if the transmission is about to call it quits mechanically, symptoms will worsen after a service. But you just ruled that idea out.

    I can appreciate/understand you asking. Np! So far I have been making things better. Not worse lol. This is the last mechanical hurdle left. I'd like to DYI it. I am extremely mechanically inclined. I've done about everything you can do to a car but tear a automatic trans apart. But with a book I'd do it. The solenoids/wiring is easy to replace other then dropping the tranny. And I can do that. been there. Done that before. The issue is the side cover has to come off to do the solenoids/wiring. The 1-2 accumulator is under the bottom cover. And the shift kit replaces that. it's an easy job.

    I am probably gonna take it back to the shop and let him look at it again. the guy is good and had done other work for me. If the price is right I'll have him do it.
     

    jkaetz

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    It looks like it's a 4t65e which is a pretty common transmission. What you described could very well be the clutch pack for the one two shift slipping. If the transmission doesn't think the shift is happening fast enough it will apply more and more pressure up to its limit. If you are scanning the vehicle, log the transmission shift time, it will for sure spike if the clutches are slipping but will likely not set a code until it gets worse. The only real fix is a rebuild with new or better clutches but a shift kit should extend the life of the clutches.
     

    1911ly

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    It looks like it's a 4t65e which is a pretty common transmission. What you described could very well be the clutch pack for the one two shift slipping. If the transmission doesn't think the shift is happening fast enough it will apply more and more pressure up to its limit. If you are scanning the vehicle, log the transmission shift time, it will for sure spike if the clutches are slipping but will likely not set a code until it gets worse. The only real fix is a rebuild with new or better clutches but a shift kit should extend the life of the clutches.

    I do believe that's the tranny that's in there from what I have researched too. And I would not doubt there is wear. I'll have the shop run the scan tool again now that the mounts are replace. See if it shows anything different. the mounts were so bad he didn't want t drive it hard. Any the trans mount was really shot. I might just go ahead and try a Transgo shift kit and see what happens before I drop the tranny and repair or replace. It's not that much of a waste of $$. If I can get a lil more life out of it that would be good. It's just a beater first car.

    thanks for the tip/info.
     

    1775usmarine

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    I had an 05 impala that would do that. It pissed me off but it was a common issue and a TSB was found when I could log into Mitchell on Demand while going to school for diesel etch. Early this year I finally got the 3.4L lower intake death wish and sold the car. Now I drive a 15 TDI which the EPA deems harmful, more so than them polluting the yellow river go figure.
     

    1911ly

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    I know close to jack about vehicles.



    But it's good to know we can still use the word tranny







    carry on

    Hey I am in to tranny's, what's the problem?? :dunno:

    Update: I am just reading on a GM tech forum that the O rings are known to fail on the 1-2 accumulator. And that can cause this issue. I guess the shift kit comes with O rings. Hence why a Shift kit can fix the problem?? I may be on to something??

     

    Woobie

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    That sounds encouraging. Sounds like a good, inexpensive lead. When I worked in a garage, I felt it was unprofessional, as well as a rip-off, to throw parts at problems. But I've been known to try the cheap fix on my own stuff before, rather than spend the extra time diagnosing. I would try it if it were my car, but that's me. If you do, I hope it fixes it for you!
     

    1911ly

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    That sounds encouraging. Sounds like a good, inexpensive lead. When I worked in a garage, I felt it was unprofessional, as well as a rip-off, to throw parts at problems. But I've been known to try the cheap fix on my own stuff before, rather than spend the extra time diagnosing. I would try it if it were my car, but that's me. If you do, I hope it fixes it for you!

    Here is the site. 03 4T65E slipping in 1st - Page 4 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat Post #40

    I will no doubt try it.
     

    Glock22

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    Is the battery good?no corrosion on the cables?Yes a weak battery can cause your tranny not to shift properly. There's so much electronic components in a car that the battery must be good.
     
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