4r70w issues

Discussion in 'Drivetrain' started by 07GtS197, Sep 7, 2016.

  1. 07GtS197

    07GtS197 Well-Known Member

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    Im not sure if Ive already made a thread about this but here it goes. I recently sold my 85 ltd crown vic and bought a 98 p71, yea its not a mustang but the trans is the same. Anyway Ive been having a problem with it skipping second gear all together. It wont slip it just wont shift into second gear. Itll run up to about 25 mph in first then shift into third. When datalogging the ecu will command second gear and shift solenoid 1 will turn off yet it wont shift into second, just stay in first. When manually shifting 1-2-D its fine but 2-D it will freewheel, the belt will squeal, then shift into third. Also when downshifting at say 35mph, it will try to go into both first and second. Once on a datalog it went back and forth comanding first and second in a span of about 3 seconds. And to confuse me more, I got second back a few days ago perfectly then it lost it again while sitting overnight.

    A rebuilder on crownvic.net said its most likely the intermediate clutch or its snap ring (?) but if it failed how would I have gotten second back? Any experts on here? Thanks.
     
  2. Nighttrain

    Nighttrain Well-Known Member

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    Need to dig into it further. Are all the solenoids functioning, is the valve body clogged? You said its not slipping but is the fluid level correct? Smell the fluid also, usually with a bad clutch you can smell it on the dip stick. Im not saying its not the clutch and bands but before you do a rebuild hit the easy stuff first.
     
  3. 07GtS197

    07GtS197 Well-Known Member

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    All the solenoids are functioning and turning on and off when theyre supposed to. Im planning on changing the fluid and filter here soon and hope that at least helps. I was thinking its something in the valve body since its only 1 gear but from what Im reading it could be a lot of things. The fluid is pink but does smell a bit burned. My buddys dad put in some lucas trans fix before I bought it so who knows if thats affecting the smell or operation of the trans at all.

    Sometimes the speedometer will read 0 until I get to 20, coincidentally is where itll shift into 3rd at part throttle, but it rarely happens. Could it be an intermittent vss problem? Or maybe the vss isnt working properly throwing off the shift scheduling but the oss functions ok masking the problem? Im hoping its not internal but if it is Ill get another trans...
     
  4. 07GtS197

    07GtS197 Well-Known Member

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    Also what should be the torque converter slip actual? Two perameters Im looking at are tcc slip actual and expected but what are the values supposed to be at part throttle and wot?
     
  5. Nighttrain

    Nighttrain Well-Known Member

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    It could be the vss since youre getting speedometer issues. I try to stay away from bandaid fixes like lucas although their products are top knotch. Anyway try the speed sensor since you already have that issue and move on from there. Rebuilding a trans really isnt that big of a deal and may be just as expensive if not cheaper as a good used or rebuilt trans. A burnt smell can tell you alot about what your clutches are doing.
    I dont know the stock converter specs have to check ford.
     
  6. lwarrior1016

    lwarrior1016 Moderator Staff SN95 Supporter

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    Can you take a picture of the parameters you are seeing? That lucus stuff is not really good for transmissions, and at best its a bandaid. I feel like its more of a small puncture wound and itll make you bleed out. So drain that stuff out of there. Then before you get too far, fix the speed sensor issue. Thatll definitely cause shifting issues. When you drop the pan, take a picture of the inside and post it up.

    Are you asking for a description of what tcc slip is or what the difference between the two parameters is?

    You will see tcc slip until lockup comes in, I forget where the stock tune brings it in. Maybe 2nd? Or it might be after 4th? Im not real sure. Either way, you ll see slip until lockup comes on and then the slip should be +0- not higher than 20 and will sometimes show negative. It should bounce around that area while cruising around.
     
  7. 07GtS197

    07GtS197 Well-Known Member

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    But its strange that its only a select few times that the speedo read 0 until it reached 20. Ive noticed that if I took the oss revolutions per minute and divided that by the currect speed it usually ended up with a 42.xx but at lower speeds it was erratic which leads me to believe either the vss or oss isnt working correctly but only at certain times and speeds. I can get a new vss today and mess with it tomorrow.

    I can take pics, what do you need in particular? I have files on hand but Ive uploaded them to my computer and they wont open even though theyre csv files. I can only see them in the forescan lite app. Ill drop the pan here soon. I know the difference between the two but what causes the pcm to set a certain number for torque converter slip and what is normal for accelerating? My tcc actual slip will shoot up sometimes while accelerating and it shows tcc expected slip should be 1020 all the time practically.

    One thing Ive read is that the pcm tells which gear the trans is in by taking the oss, gear ratio and rpm and calculating the gear (something like that) but when it commands 2nd gear the rpms in 1st just keep rising but its not throwing any codes. With the outputs it should have no problem seeing that its not shifting. Id also like to add if I were to manually shift from 2nd into drive it will neutral for a second then go into 3rd.
     
  8. JerZeyStangz

    JerZeyStangz Well-Known Member

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    This is a shot in the dark but do you think you have a damage spring in the valve body. I remember reading a couple threads in the past that spring/accumulator controls the 2nd gear shift. Anyways, maybe you can save the transmission mission by using Amsoil Engine/Trans flush. Its a detergent with no harsh chemicals that will clean the clutch plates of varnish. You run it for about 10-15min through the valve body selecting each gear then let the trans cool and drain with fresh fluid.

    Here is some literature that you might find interesting: http://www.tccoa.com/articles/tranny/transmission/page15.shtml

    http://www.tccoa.com/articles/tranny/transmission/
     
  9. 07GtS197

    07GtS197 Well-Known Member

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    The earlier 4r70w's have the problem with the accumulator piston seal but I should have the updated design. Ive looked into that but everyone said it wouldnt cause a no 2nd gear condition but it does seem possible. Hmm Ill try out that fluid you mentioned, worst case scenario Ill need a rebuild and I could probably use one now lol. Thanks.
     
  10. JerZeyStangz

    JerZeyStangz Well-Known Member

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    No problem! When my buddy damaged his 4R70W in his 96 GT Vert, he lost second gear. The only way the car would shift into second is when he let of the gas. He thrashes on all his cars and I know that mod engines love to rev and this transmission hates repeated high rpm shifts. Darrin Burch who is guru on Ford transmissions told me that when I asked him what can I do to beef it up. I asked if a upgraded valve body would help, but he said its just band-aid. The 4R75W has superior parts to the older 4R70W. For now, try the Amsoil Engine/trans fluid flush, dump it in the trans dip stick tube and run it through the whole transmission and put a new filter on it. It wouldn't hurt investing maybe 45-65 dollars in new fluid and filter. While your at it take a peak at the valve body and see if you have damaged spring, its worth a shot.
     
  11. 07GtS197

    07GtS197 Well-Known Member

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    Once my fiance is done shopping Ill head over to advance. Im in the process of buying fluid, a filter and a dorman trans pan. Mercon v is hard to find especially in gallon jugs! Im willing to bet its something in the valve body since I got second gear back then I lost it again lol. The only difference when applying manual 2nd gear and 2nd gear in drive is that 2nd gear in drive uses the intermediate one way clutch. I cant see that going out since I lost 2nd then got it back again so it still has life in it.

    The one thing I still dont understand is that the computer commands 2nd and sees that Im not in 2nd when the rpms dont drop and doesnt throw a code. Maybe its not throwing a code because Im using an elm327 scanner? I tried using my x3 tuner too but nothing.
     
  12. 07GtS197

    07GtS197 Well-Known Member

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    I think Im close to solving it and if Im right there are a few things wrong. There is a tsb for the 98 crown vics that says the 1-2 can be delayed as much as 9-15mph when cold, likely the 1-2 shift accumulator is broken causing a delayed 1-2 shift, the trans fluid rarely reaches operating temp (150-180*) and its throwing a U1059 code. All of this would make me think the tsb was never taken care of, the 1-2 accumulator spring is broken causing a late shift, the trans temp makes the pcm use the cold trans shift scheduling and by the time itll scedule the 1-2 shift itll change it to 3rd gear since its already going fast enough to go into 3rd, the vss is not working properly under 20mph, the trans doesnt reach operating temp for a while after its been running and that code indicates a fault in the transmission range sensor. On my datalog it showed an error while shifting a few times and I somehow regained 2nd gear no problem after the transmission reached about 160 degrees. Sooo my theory is that there are multiple faults causing the transmission to loose 2nd until it fully warms up.
     
  13. JerZeyStangz

    JerZeyStangz Well-Known Member

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    I would go from easiest to hardest. Check various sensors that apply to shift schedule and if everything checks out drop the pan to look at the accumulator/springs
     
  14. 07GtS197

    07GtS197 Well-Known Member

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    Im going to have to do that. I took her for a spin today and within a mile she had 2nd gear again. Maybe its something sticking in the valve body? Its not temp related because there is no correlation between temp and regaining second after looking at my logs. Now I did use seafoam trans tune (the only thing I could find) which might have helped. Before I used it I could eventually get 2nd gear back but now that its in I got 2nd gear back within a mile. Coincidence? Im not sure but it sounds valve body related since there is no correlation between temp or speed and when I get 2nd again. Im sure there are other things at work now like the accumulator springs which are probably exacerbating the problem so those need to be taken care of too. Ill be dropping the pan once I get the money for a filter, dorman pan and fluid, which will be soon.
     
  15. JerZeyStangz

    JerZeyStangz Well-Known Member

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    Amsoil OE Fluid with a high end Wix filter or equivalent. I also suggest Amsoil engine/trans flush again as I said previously lol....it is very gentle in removing varnish or deposits on clutch plates or metal services, mind you it will take a few hundred miles but its worth it in the end.

    You could very well just had a severely clogged VB and running the seafoam just freed some gummed up parts. Definitely inspect the valve body for any wear in the bores where the accumulator/springs would be.

    A little testimony to the flush! Ever since my daily driver has been down I've been driving the mustang all summer. I did the flush maybe last year but probably put less than 100 miles on it until I started driving at the BEGINNING of the summer till now. Mind you I've been running synthetic since I owned this car and that was the first time using the flush. I noticed my oil pressure got way better and the engine is bit happier. These engines are really built to tight specs because it must of cleaned something internally for me to get better oil pressure. I thought running synthetic was good enough, but it helped a lot. My valve seals would let oil seep and I would get a puff on blue smoke on hot days during start up but now it doesn't do it anymore...just my observations.
     
  16. 07GtS197

    07GtS197 Well-Known Member

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    Ill try to find that stuff maybe advance or walmart carries it? I know autozone doesnt. When I drop the pan Ill pull the entire valve body and inspect it closely while out of the car to make it easier. Im thinking its just something stuck in the valve body and no biggie. Thanks for the advice and testimonial!
     
  17. JerZeyStangz

    JerZeyStangz Well-Known Member

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    No problem man! Some autoparts stores carry it but since its such high niche product you probably would have to order it. Post pictures when you drop pan. I am curious to see what it looks like underneath there.
     
  18. Nighttrain

    Nighttrain Well-Known Member

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    Like a trans....with oil dripping everywhere......hehe
     
  19. JerZeyStangz

    JerZeyStangz Well-Known Member

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    Hahaha, awh man.
     
  20. 07GtS197

    07GtS197 Well-Known Member

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    There is some fluid between the trans and engine oil pan. Ill have to take a closer look at it to make sure it really is trans fluid. Ill definitely post pics of what I find. Im willing to bet the valve body will have to come out and be thoroughly inspected, maybe even rebuilt. Yay.