Lenard Posted November 26, 2009 Share Posted November 26, 2009 *I"m using TC as short for Torque Converter* i got my truck outa the shop 2 weeks ago, next day driving to the city running along at 70 mph and all the sudden i notice my rpms go up then back down, up then down, so i started paying attention and it was my TC flipping on and off. so i pulled over checked fluid, it was low, mechanic did not get it full after replacing tranny lines :fs1:(he got a @$$ chewing) so i filled it up, and it quit, for a while, now its just sometimes it does it, tranny does not slip at all, up's and down shifts fine, its just when it's in OD the TC starts acting up, and i also noticed, that when it start's flipping on and off, if i give it more gas, truck will starts to accelerate and the the TC will flip on or off and rpms will go down like they are supposed to, but as soon as i let off the gas, TC flips again and rpm's go back up another 400 or so. I don't know which way is on or off for the TC, maybe somebody can enlighten me. And it does not do this at any regular time, it's only done when its warm cause i never drive the truck fast enough to get outa 2nd till its warmed up, but i can be cruising for a while and it does it, or as soon as i hit OD it will start doing it, Tranny is not getting hot that i know off, fluid level is good, no leaks, and is red color, so its not burnt at all. this is on my 88 aw-4 4x4 :help: :help: Link to comment Share on other sites More sharing options...
aemsee Posted November 26, 2009 Share Posted November 26, 2009 When the convertor locks up is when the rpm's go down. It may just be a glitch in the tps. What was done to the trans besides cooler lines? How are the regular shift points? Same as before the work? Link to comment Share on other sites More sharing options...
kellyj Posted November 26, 2009 Share Posted November 26, 2009 I'm having the exact same problem, just happened yesterday for the first time in 6 months. 1987 MJ 4.0 4x4. My fluid level has not been low, looks good. Happens when warm, all of the sudden engine roars and feels like it is jumping into a lower gear. Any clues? Link to comment Share on other sites More sharing options...
Lenard Posted November 26, 2009 Author Share Posted November 26, 2009 When the convertor locks up is when the rpm's go down. It may just be a glitch in the tps. What was done to the trans besides cooler lines? How are the regular shift points? Same as before the work? yes shift point all the same, all i had done was fix the return line from the cooler to the tranny, the rubber was denigrating so i just had him replace it, but i have no idea how he lost 2 qts of fluid that way :nuts: cause he put a qt in and then the next day i added another qt. I'm pretty sure it's in the tranny cause i can feel it "kick" a little when it does this I'm having the exact same problem, just happened yesterday for the first time in 6 months. 1987 MJ 4.0 4x4. My fluid level has not been low, looks good. Happens when warm, all of the sudden engine roars and feels like it is jumping into a lower gear. Any clues?do you have a rpm gauge? is it actually down shifting to 3rd? mine is only jumping around 400 rpms up and down Link to comment Share on other sites More sharing options...
kellyj Posted November 26, 2009 Share Posted November 26, 2009 Unfortunately no tach. I have a feeling the tps needs to be replaced, gonna try that first. When this happened 6 months ago, took it to a shop and they drove it for 2 days and of course, it never acted up so they couldn't find anything to fix. When it happens and the engine rpms increase, just feels like no power going to the trans, but I could be wrong. Also have to remember its 22 years old! :cheers: Link to comment Share on other sites More sharing options...
Lenard Posted November 27, 2009 Author Share Posted November 27, 2009 anybody else have ideas? Link to comment Share on other sites More sharing options...
Lenard Posted November 30, 2009 Author Share Posted November 30, 2009 bump, need idea's guys, also noticed today when it was acting up, when i would be running a good speed 50-70mph and let off the gas the rpms would all but drop to idle speed and as soon as i hit the gas they came back up to normal. i had a car that did this to me and the tranny died soon afterward, I'm praying this ain't the case. :( Link to comment Share on other sites More sharing options...
freakjeep93 Posted November 30, 2009 Share Posted November 30, 2009 my step moms car does this all the time the rpms will just "bounce" around we all think its the tps Link to comment Share on other sites More sharing options...
kellyj Posted November 30, 2009 Share Posted November 30, 2009 I installed a new tps over the weekend and so far so good. Ran a check on the magnetic sensor on the crank and it checks out ( thankfully, as it is in a tough spot to change! ) tps was the adjustable type, .8 volts is the correct setting with it connected and the key on, testing the pigtail with the flat connector. I'll let ya'll know if it acts up again. Link to comment Share on other sites More sharing options...
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