Transmission shifting at HIGH RPM!!!!

Discussion in '80-Series Tech' started by diego355, Jan 18, 2011.

  1. diego355

    diego355

    Messages:
    286
    Location:
    Calgary, Canada
    Hi everyone.
    Today driving to work my transmission start acting weird. It wont shift normal, first second and third shift arround 4000 rpm and rough. In first gear the shift is really hard and second is not that bad and third is smooth but also arround 4000 rpm.
    Any ideas?

    1991 Cruiser 3F-E 146000 km
  2. Michael Hanson

    Michael Hanson

    Messages:
    7,381
    Location:
    Plano texas
    Id replace the shft cable, they stick in side the sleeve. You will need to drop the trans. pan. MIke
  3. Monty231

    Monty231

    Messages:
    116
    Location:
    Mt Juliet, TN
    Is power mode selected?
  4. Eicca

    Eicca Professional Noob

    Messages:
    1,653
    Location:
    Utah County
    1991s are too archaic to have Power Mode :flipoff2:

    Agreed on the tranny cable, make sure it's not sticking or maladjusted.
  5. thestunts

    thestunts

    Messages:
    601
    Location:
    Roseville, CA
    Ive had this same issue in my 94 but noticed it only happens when the engine & tranny are cold. Once it warms up it tends to go away ..

    Subscribing to see what may be used in "general" to help me as well.

    Let us know what the cause is if not directed by a mud member, I'm curious.
  6. darwink1

    darwink1

    Messages:
    2,403
    Location:
    Sudbury Ontario Canada
    What about the cdl? Mine shifts at around 3g's with it on..

    D
  7. CJF

    CJF

    Messages:
    6,383
    That's even more evidence it's likely a sticking cable.
  8. CJF

    CJF

    Messages:
    6,383
    To both of you with this issue:

    Unook the cable from the throttle body and then squirt some wd-40 down the cable.

    I'll bet that takes care of it, at least temporarily (which will confirm the diagnosis).
  9. thestunts

    thestunts

    Messages:
    601
    Location:
    Roseville, CA
    Thanks.... I'll probably replace mine as it's beaten to hell and pieces of the exterior rubber are missing.. cracked etc ... THANKS CJF !
  10. Tools R Us

    Tools R Us

    Messages:
    17,815
    Location:
    Chandler, AZ
    The 3FE trans is hydraulic, so the kick down cable is exactly that, if stuck at the fully open position will shift like the throttle is open/floored. The 1FZ trans is shifted by the maps in the ECU, electronically shifted. The "kick down" cable only adjusts shift smoothness/harshness, has nothing to do with when it shifts.
  11. Tools R Us

    Tools R Us

    Messages:
    17,815
    Location:
    Chandler, AZ
    Low range uses a different map, holds gears longer, shifts at a higher RPM and doesn't shift 4th(OD) gear. In my experience, this change happens only when in low range, switched by the L4 position switch. Locking the CDL in high range should have no effect on shift points?

  12. darwink1

    darwink1

    Messages:
    2,403
    Location:
    Sudbury Ontario Canada
    Hmmm, if I use the cdl in high it shifts at the higher rpm, same as in low. Ineresting. At least this helps me to remember to click it off when I dont need it..

    D
  13. Tools R Us

    Tools R Us

    Messages:
    17,815
    Location:
    Chandler, AZ
    :whoops: I should have pointed out that my experience is with the later A343 equipped rigs, the A440 rigs may differ? But was under the impression that all of them changed mapping by the L4 position switch? If that isn't true, what changes the map on the A440 rigs?
  14. darwink1

    darwink1

    Messages:
    2,403
    Location:
    Sudbury Ontario Canada
    No fricking clue man lol. Only reason I noticed was last time I took it on a trail I forgot to turn the cdl off when I got on the hwy. Tranny was shifting at 3g and would not go into od. After some initial confusion I clicked the switch and the shift points went back to normal.

    Someone w a 93-4 must know the story.

    D
  15. diego355

    diego355

    Messages:
    286
    Location:
    Calgary, Canada
    I think i found what is the problem but im not sure. The cable in the throtle is loose, well it looks loose to me like Tools R Us said "The 3FE trans is hydraulic, so the kick down cable is exactly that, if stuck at the fully open position will shift like the throttle is open/floored".
    Can any one with the 3F-E engine post a picture or send me a email to see how is supossed to look like?
    diego.jimenez89@gmail.com or facebook Diego Jimenez

    Thanks alot
  16. 86tuning

    86tuning

    Messages:
    2,558
    Location:
    Vancouver BC
    there's 2 cables on the throttle.

    one is attached to the gas pedal.

    the other is the kickdown cable and is attached to the trans. It's not supposed to be slack. Spray some penetrating oil (wd40 or better) down the cable and see if you can make it go back into the cable housing.
  17. I have this exact issue but ONLY when in 4-low. I can creep it up to just over 3,000 rpm (HDJ81-diesel) and then when it shifts up it ROCKET PROPELS me forward. I have the A442F (elec. solenoid) transmission in a 93 HDJ81 cruiser.

    Because it only happens in 4-low and 4-high is as smooth and normal as can be, it makes me think it's something electric. Any ideas?

    Andrew
  18. Tools R Us

    Tools R Us

    Messages:
    17,815
    Location:
    Chandler, AZ
    No idea about the diesel, but the gas unit uses two shift maps, one for high and one for low range. The low range map holds each gear longer, for better power in low range. On the gas unit, the map is changed by the L4 position switch on the transfer, if unplugged the trans will always use the high range shift map. L4 position switch also automatically locks the CDL, so if you want it to lock would need a manual switch.
  19. Thanks Tools, this is what I've found as well. The holding of each gear longer is alright, except the actual change-over into 2nd gear (in 4-low) is incredibly rough. It literally spins all 4 tires and launches the truck forward.

    Is the L4 position switch also used for the "Pin7" mod? Allowing you to have 4-low without CDL? I have done both the Pin7 mod and installed a CDL switch, but this problem was occuring before I did either and still is a problem.

    Assuming the Pin7 mod is completely different, is the L4 position switch easy to reach and unplug for testing purposes?
  20. Tools R Us

    Tools R Us

    Messages:
    17,815
    Location:
    Chandler, AZ
    Does the diesel trans have the trans cable (from the throttle cable to trans valve body)? If so, it is a progressive pressure regulator, the tighter it is adjusted, the firmer it will shift. Most noticeable in low range.

    Been a while, so IIRC: The output from the L4 position switch goes two places; to the CDL relay and ECU. The pin 7 interrupts the L4 position switch signal to the CDL relay, so it no longer auto locks the CDL, but leaves the ECU connection to retain proper shift mapping. If the L4 position switch is unplugged, both jobs are done.

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