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Old 08-09-2012, 04:15 PM   #1
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Engine or Trans ?

My 2002 jeep tries constantly to shift into passing gear when i get to about 50 and 60 mph , you can feel it and see the rpm's going up and down , does anyone know if this is a trans problem or maybe a sensor problem?? thanks

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Old 08-09-2012, 05:15 PM   #2
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What gears and transmission are in your rig?

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Old 08-09-2012, 05:24 PM   #3
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What gears and transmission are in your rig?
and what size tires?
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Old 08-09-2012, 05:38 PM   #4
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What gears and transmission are in your rig?
Not sure about gears i bought jeep used, tranny is stock 3speed auto.
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Old 08-09-2012, 05:38 PM   #5
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and what size tires?
tires are 32x 11.5s
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Old 08-09-2012, 05:44 PM   #6
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I should add that this problem just started, and normally i am at 2000 rpms to go 60mph. Tv cable is fine also .
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Old 08-09-2012, 05:55 PM   #7
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Fluid level ok?
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Old 08-09-2012, 06:04 PM   #8
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Is it actually shifting into second gear,
or is it just unlocking the converter?
How much does the rpm change when this happens?
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Old 08-09-2012, 06:14 PM   #9
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Fluid level ok?
ya fluid is ok
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Old 08-09-2012, 06:17 PM   #10
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Is it actually shifting into second gear,
or is it just unlocking the converter?
How much does the rpm change when this happens?
I think its going into second gear , it starts at about 1800 rpms and jumps to 24 to 2500 rpms.
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Old 08-09-2012, 06:46 PM   #11
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Ok just noticed when i turn jeep off then restart and put into reverse i hear a sucking air sound for a second, could that be the prob??
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Old 08-09-2012, 07:24 PM   #12
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I don't know what the sound is or why it makes that sound sometimes.
But I have heard it before, and I have seen it mentioned on this forum before.
Another member said that it sounded like a release of air, who knows.

Are you trying to accelerate when your trans is downshifting, or are you driving uphill?
or are you on a flat road at a steady speed?
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Old 08-09-2012, 08:09 PM   #13
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I don't know what the sound is or why it makes that sound sometimes.
But I have heard it before, and I have seen it mentioned on this forum before.
Another member said that it sounded like a release of air, who knows.

Are you trying to accelerate when your trans is downshifting, or are you driving uphill?
or are you on a flat road at a steady speed?
It does not matter what the incline is, its just about speed, anything over 50 and all hell breaks loose.
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Old 08-09-2012, 08:25 PM   #14
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I know you said the Tv cable was ok, but as far as I know nothing but the Tv cable should cause the trans to down shift at 55mph.
Have you tried driving it with the cable disconnected to see if it would make any difference?
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Old 08-09-2012, 08:31 PM   #15
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I know you said the Tv cable was ok, but as far as I know nothing but the Tv cable should cause the trans to down shift at 55mph.
Have you tried driving it with the cable disconnected to see if it would make any difference?
No have not tried that , but from what i have read tv cable would be affecting all the shifting not just this one particular problem. maybe i read that wrong?? I am at a loss.
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Old 08-09-2012, 09:16 PM   #16
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The cable does control up shifting & down shifting, based on the throttle position.
Driving without it connected = very quick up shift, 1-2-3 within about 25 feet,
and of course it won't down shift until you come to a complete stop.
I just disconnected mine and drove it to see how it would shift.
I'm not saying to leave it disconnected for a long time, just try it for a few miles & see if the down shift problem goes away.

I have the 32rh in my '01, yours should be the same.
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Old 08-10-2012, 06:10 PM   #17
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The cable does control up shifting & down shifting, based on the throttle position.
Driving without it connected = very quick up shift, 1-2-3 within about 25 feet,
and of course it won't down shift until you come to a complete stop.
I just disconnected mine and drove it to see how it would shift.
I'm not saying to leave it disconnected for a long time, just try it for a few miles & see if the down shift problem goes away.

I have the 32rh in my '01, yours should be the same.
I did a test on the way home today. I put the car in second gear at 55mph and the rpm's shot way higher than they do when i'm having my other problem,so its not trying going into passing gear, i think something else is going on.
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Old 08-10-2012, 06:26 PM   #18
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Sounds like the converter is unlocking, I'm not a TJ owner so forgive me. But does your jeep have overdrive? If so try turning it off and see if maybe its kicking it of O/D. Have you changed the transmission fluid and filter? Like I said not a TJ owner, I'm a YJ owner.
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Old 08-10-2012, 06:41 PM   #19
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Sounds like the converter is unlocking, I'm not a TJ owner so forgive me. But does your jeep have overdrive? If so try turning it off and see if maybe its kicking it of O/D. Have you changed the transmission fluid and filter? Like I said not a TJ owner, I'm a YJ owner.
No overdrive, and I just bought new fluid and filter for this weekend. I'm gonna try a complete flush since a forum member gave a great write up on how to do it. If the converter is unlocking , is that a big problem??
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Old 08-10-2012, 07:23 PM   #20
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With only 2K on the tach at 60 mph, you're undergeared for your 32" tires which is increasing pressure inside your 3-speed 32RH transmission that makes it want to unlock the torque converter more than it should, plus it is probably close to wanting to go into 2nd gear too.

My guess is your axle ratio is 3.07 which produces too low of an engine rpm for 32" tires. Regearing your axles to 4.10 (3.73 at the highest) will fix your issue.

Unless the previous owner removed them, you can find axle tags bolted onto both differential covers that have the axle ratio embossed into them. The "3 73" on the below tag indicates the axle has 3.73 gearing in it.
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Old 08-10-2012, 09:59 PM   #21
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With only 2K on the tach at 60 mph, you're undergeared for your 32" tires which is increasing pressure inside your 3-speed 32RH transmission that makes it want to unlock the torque converter more than it should, plus it is probably close to wanting to go into 2nd gear too.

My guess is your axle ratio is 3.07 which produces too low of an engine rpm for 32" tires. Regearing your axles to 4.10 (3.73 at the highest) will fix your issue.

Unless the previous owner removed them, you can find axle tags bolted onto both differential covers that have the axle ratio embossed into them. The "3 73" on the below tag indicates the axle has 3.73 gearing in it.
the tags are in my tool box, i will look at them on sunday, My only question is why did this just start happening?? I have put 10.000 miles on old engine and 1.500 on new atk engine, and never had this issue, I mean it really just started doing this
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Old 08-10-2012, 11:48 PM   #22
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Originally Posted by mrbat23 View Post
and normally i am at 2000 rpms to go 60mph.
If these numbers are accuate, you do have 3.07 gears.

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Originally Posted by mrbat23 View Post
If the converter is unlocking , is that a big problem??
Constant locking & unlocking can cause the transmission to overheat & overheating is a common cause of transmission failure.

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My only question is why did this just start happening??
How many miles are on the transmission? I'm beginning to think that your transmission is about to fail. I hope I'm wrong & maybe flushing it out will fix it.
I have 32" tires, 4.0 engine, 3.07 gears, 32RH trans, & I have not experienced the erratic shifting that you are describing.
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Old 08-11-2012, 03:37 PM   #23
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Ok this is strange, i had a ground issue pop up recently, every time i would hit a bump my gauges would stop working and my radio would shut off, i located the bad ground, it was the one on the firewall and very loose.So today i did 70miles to work in a 65mph zone and not one issue at all, and better yet my low idle is also back to normal,can this be related to a bad ground??
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Old 08-11-2012, 08:22 PM   #24
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Btw what should my rpm's be at 60 mph?? Even though my ground issue seems to have solved my problem, it was also about 30 degrees cooler than the last time i drove it , and now i am really concerned about my axle ratio.also thanks so much for the help.
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Old 08-11-2012, 10:51 PM   #25
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Ok this is strange, i had a ground issue pop up recently, every time i would hit a bump my gauges would stop working and my radio would shut off, i located the bad ground, it was the one on the firewall and very loose.So today i did 70miles to work in a 65mph zone and not one issue at all, and better yet my low idle is also back to normal,can this be related to a bad ground??
Yes, a bad ground could have been the cause of your erratic shifting.
The PCM is what controls the locking & unlocking of the torque converter.
If it's shifting ok now, you may have found & fixed your problem.
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Old 08-12-2012, 10:16 AM   #26
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It sounds to me like your shift solenoids are starting to go, it happened to me in my old chevy. I replaced them, which fixed the problem, until about 6 months later when the entire trans. detonated!
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Old 09-01-2012, 05:50 AM   #27
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mrbat23
is your check engine light on if so change o2 sensor it has a power wire that go's to the trans if its shorting out it does something to the trans that makes it shift in to 2nd gear had same problem changed it now it gone

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