88 Bronco, AOD Downshifting problem.
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88 Bronco, AOD Downshifting problem.
88 Bronco 302, AOD tranny.
I have had this problem over the last few months but thought nothing of it. I changed my tranny fluid and filter(along with torque converter fluid). Shifting is just fine no problems I even seem to have a little more power in OD than I did before the fuid change. But the problem I am having I had before the fuid change, when slowing down to stop the RPM's drop to 400 then SHOOT up to 1,100 with a hard downshift from 2nd to 1st. I think it is my ideling, my Bronco idles with a warmed engine at 800-1,000RPM's in park or in gear.
I think that idle is too high, my idle speed went up after I cleaned out my IAC valve, I removed the valve from the IAC motor so I did not get any cleaning fluid in the motor. What could the problem be?? the TPS?? if so can the TPS be cleaned in some way??
Also could resetting the computer fix this, does it need to relearn the IAC now that it's clean??
EDIT, I just thought of something, I really OPENED up my air intake, could that be the problem???? Too much air???
Thanks,
I have had this problem over the last few months but thought nothing of it. I changed my tranny fluid and filter(along with torque converter fluid). Shifting is just fine no problems I even seem to have a little more power in OD than I did before the fuid change. But the problem I am having I had before the fuid change, when slowing down to stop the RPM's drop to 400 then SHOOT up to 1,100 with a hard downshift from 2nd to 1st. I think it is my ideling, my Bronco idles with a warmed engine at 800-1,000RPM's in park or in gear.
I think that idle is too high, my idle speed went up after I cleaned out my IAC valve, I removed the valve from the IAC motor so I did not get any cleaning fluid in the motor. What could the problem be?? the TPS?? if so can the TPS be cleaned in some way??
Also could resetting the computer fix this, does it need to relearn the IAC now that it's clean??
EDIT, I just thought of something, I really OPENED up my air intake, could that be the problem???? Too much air???
Thanks,
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Joined: Apr 2003
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From: Carson City
Mine has the same problem. I found out that it was the torqe converter. The tq is in full mechanical lock-up in over-drive, so when you stop the tq isn't unlocking cuasing the engine to bog down untill it gives. I was driving for a while like that until I found out it was the tq-I bet this isn't good for the motor. Try putting it into drive, not o/d and see if it still does it, I bet you it won't. Your tq is shot and needs to be replaced. I just use o/d when i'm going over 40mph now and down shift before coming to a stop. Btw how may miles does your tanny have? Mine has 203,000+ and my tranny also slips alittle when it's cold, but the motor is still going!
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I SURE HOPE THAT'S NOT THE PROBLEM!
Don't have the money to fix that!
Mine has 140,000 and I just did a full fluid drain and filter change(first time it's been done) and it seemed to make it worse(just a little), I will try to drive it tomorrow without OD and see if it still does it, I will look around for a TC while I'm at it, how hard/long is it to change one out???
EDIT, I started another thread in the Transmission section, if you don't mind can you post over there from now on?? Before you replied I posted over there and asked the Mod to delete this one.
EDIT AGAIN, I have been reading and found somone with the problem with their TC but they had downshift problems in all gears not just 2-1......I have heard about the Govoner causing problems, where is it and how do I check it??
Thanks
Don't have the money to fix that!
Mine has 140,000 and I just did a full fluid drain and filter change(first time it's been done) and it seemed to make it worse(just a little), I will try to drive it tomorrow without OD and see if it still does it, I will look around for a TC while I'm at it, how hard/long is it to change one out???
EDIT, I started another thread in the Transmission section, if you don't mind can you post over there from now on?? Before you replied I posted over there and asked the Mod to delete this one.
EDIT AGAIN, I have been reading and found somone with the problem with their TC but they had downshift problems in all gears not just 2-1......I have heard about the Govoner causing problems, where is it and how do I check it??
Thanks
Last edited by Wolfman2405; Sep 25, 2003 at 09:17 PM.
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From: Medina, Tn.
Try it while NOT using OD and see if it makes a difference like 89Bucknbronc says. Also, I had a friend that had a similar problem and it was his VSS (vehicle speed sensor) on the transfer case and was less than $40. from AZ. Try some Lucas transmission fix and see if that makes a difference. I use 2 quarts in mine and it has cured a few problems for the past year and a half. Many will argue this point, but sometimes, changing the tranny fluid WILL make the tranny worse with the new slicker fluid not grabbing the plates like the old sticky fluid did. Lastly, the TPC can not be cleaned and on our years, it is not adjustable either. I replaced that and the IAC and mine idled about 1200 when warmed up. I just did what you are not supposed to do and adjusted the idle stop screw on top of the manifold early last year and have had NO problems whatsoever. IF you do adjust it, make sure that it is warmed up 1st.
Just my dimes worth.
Just my dimes worth.
Senior User
Joined: Jun 2003
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From: Atlanta Georgia
I may be wrong, but I think the converter on an AOD is locked up in 3rd and 4th, And the converter itself doesnt lock up its bypassed by the inner shaft and directly drives 3rd and 4th gear.
But I could be wrong
But I could be wrong
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ok the problem has gone away!!!! I tired driving with OD off and it downshifted smoothly, when I put OD on it kicked from 2-1. I drove to Walmart to get some coolant and did'nt pay too much attn but I thought it was smoother. Now after 30 miles since fluid change the hard downshift is gone. Heres the strange thing, when I was going to walmart I had to stop for a slow car, I then put my foot back on the gas and the pedal dropped down a little and something CLICKED, could something in the cables been messed up, for example could the TV cable been binding up some....Oh well atleast it works now. Since It is working I hate to do anything to it, but would it hurt to use some Lucas oil in it?????
Or just leave it alone since it's working?
Thanks for your help guys!
Or just leave it alone since it's working?
Thanks for your help guys!
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From: Carson City
I have lucas oil stablizer in my engine oil, I didn't know you can put that stuff in the tranny, can you? I am afraid to have my tranny flushed, and it will turn out to make it worse, I might try having it flushed w/ new filter and putting lucas oil, and tranny additive in it.
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They have a lucas oil product for your tranny that is supposed to smooth shifting and seal any leaks, Well mine shifts smoothly now and I have no leaks so I don't want to put anything in it.
I would drain and fill mine if I were you, mine had never been done and with 140,000 miles on it I would have expected a problem. My strange downshifting problem started a few weeks if not months ago so the fluid drain and fill had nothing to do with it. Seems whatever it was has corrected itself.
I would drain and fill mine if I were you, mine had never been done and with 140,000 miles on it I would have expected a problem. My strange downshifting problem started a few weeks if not months ago so the fluid drain and fill had nothing to do with it. Seems whatever it was has corrected itself.
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Well the problem came back
It happens when the tranny is cold and then it becomes a intermitten problem when the tranny is warm, sometimes it will and sometimes it won't. I can tell when it's going to do it. When I begin to slow down from 55-60mph when I get to about 40mph I can feel the tranny beging to bog down and then it will let loose smoothly. But when I am slowing down if it don't let out by 30mph then I know it's gonna kick down hard at the last minute, drops me down to 400rpm and then at about 15mph it KICKS OUT and goes up to 1,100rpm.
Exactly how does the converter lock up?? I have heard somthing about two ball berings that will slide out and lock it in, is this correct or did I read the wrong thing?? Should I pop the $8 and get some Lucas Tranny stop slip stuff???? This is really getting annoying and it can't be good for the tranny and rear end. One more thing the one time it kicked down hard it made my ABS pulsate a little
It happens when the tranny is cold and then it becomes a intermitten problem when the tranny is warm, sometimes it will and sometimes it won't. I can tell when it's going to do it. When I begin to slow down from 55-60mph when I get to about 40mph I can feel the tranny beging to bog down and then it will let loose smoothly. But when I am slowing down if it don't let out by 30mph then I know it's gonna kick down hard at the last minute, drops me down to 400rpm and then at about 15mph it KICKS OUT and goes up to 1,100rpm.Exactly how does the converter lock up?? I have heard somthing about two ball berings that will slide out and lock it in, is this correct or did I read the wrong thing?? Should I pop the $8 and get some Lucas Tranny stop slip stuff???? This is really getting annoying and it can't be good for the tranny and rear end. One more thing the one time it kicked down hard it made my ABS pulsate a little
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Further up this thread, user "Gacknar" had the correct description of "lock up" on the AOD. The torque converter (TC) does not lock or unlock. Instead, the AOD has two concentric input shafts. One is after the TC, so it has the multiplying action of the TC. The other input shaft comes through from the front of the TC, so it is the TC "bypass". The bypass is used in 3rd gear and 4th gear(overdrive). The bypass is enabled by applying the Direct Clutch, which is one of the multiplate friction clutches. The Direct Clutch, like all the others, is controlled by the Valve Body.
A too-high idle speed can mess things up, as can a misadjusted TV (Throttle Valve, it varies an important control pressure in the trans) cable. If none of those, then I would suspect a valve in the valve body hanging up. I'm sure others here have pointed out the need for a manual to adjust the TV cable, as a mistake there can cook an AOD real fast by slipping clutches!
A too-high idle speed can mess things up, as can a misadjusted TV (Throttle Valve, it varies an important control pressure in the trans) cable. If none of those, then I would suspect a valve in the valve body hanging up. I'm sure others here have pointed out the need for a manual to adjust the TV cable, as a mistake there can cook an AOD real fast by slipping clutches!
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ok I understand now, so what is happening is for one reason or another one of those clutches are not releasing?? This might be coming from 3-2 instead of 2-1, it's hard to tell, here is how my Bronco downshifts from 55-60(OD).
When I begin to slow down at around 45 I start to feel the engine bog down and then the tranny shifts smoothly to a lower gear. As I continue to slow down I don't feel another shift until around 25 or so then all shifts smoothly(atleast it did when it was working right) now the shift at 25 is not there it waits until 15 to shift and it kicks hard when it does. my normal idling is at 700-800rpm so it is ok(I thought it was higher). The hardness of the kick is also dependant on how fast I stop, if I coast to an easy stop then it shifts ok(still a little hard) but if I make a sudden stop and it kicks HARD. I hope that all made sense. Now This TC bypass is controlled by valves in the Tranny right? so one of them must be going bad? or since this is dependant on how fast I stop could this be TV cable related. I have messed with the throttel stop before, could this be messing this up, pulling on the TV calble more or less than it should? If this was YOU where would you start??
When I begin to slow down at around 45 I start to feel the engine bog down and then the tranny shifts smoothly to a lower gear. As I continue to slow down I don't feel another shift until around 25 or so then all shifts smoothly(atleast it did when it was working right) now the shift at 25 is not there it waits until 15 to shift and it kicks hard when it does. my normal idling is at 700-800rpm so it is ok(I thought it was higher). The hardness of the kick is also dependant on how fast I stop, if I coast to an easy stop then it shifts ok(still a little hard) but if I make a sudden stop and it kicks HARD. I hope that all made sense. Now This TC bypass is controlled by valves in the Tranny right? so one of them must be going bad? or since this is dependant on how fast I stop could this be TV cable related. I have messed with the throttel stop before, could this be messing this up, pulling on the TV calble more or less than it should? If this was YOU where would you start??
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My bronco does the exact same thing as yours does. It's a pain, just started one day. Except that it doesn't do it untill it gets warm. Put mine in drive and the truck pretty much acts like nothing in the world is wrong. No problems what so ever. It's beginning to annoy me................. alot. ANy help will be greatly appreciated.
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Same Here if I disable OD then it don't do it, I am not a rich man and this can't be good on other parts in the drive line, I would like to fix this now instead of fixing more things later, and yes it is ANOYING!
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From: Connecticut
Above you described something occuring when the gas pedal was depressed on your trip to Walmart. It may be the TV cable binding. If the cable binds when you take your foot off the gas it will keep the line pressure in the transmission high causing a harsh downshift. Try pulling the cable manually by hand at the throttle linkage and see if you can feel any binding. Also, check it all the way to the transmission for kinks etc.
Mark
Mark