Is there a way to reset computer to relearn shift points?

AgBass01

Member
I recently regeared from 3.21 to 4.56 and my transmission is not shifting when I think it should. It's holding on to each gear a little longer and today I floored it to get up on the highway and it actually hit a rev limiter I guess going from 3rd to 4th. Hit 7000 rpm on the gauge and the throttle died out for a couple seconds then it finally shifted.

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WJCO

Meme King
You need a calibrator/programmer to access your pcm and change the gear ratio data.
 

AgBass01

Member
Ok. Thanks for the info. I'll give them a call. I've been looking at the bluetooth OBDII adapter and jscan app as well, might just pull the trigger and check it out myself.

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Benito

Caught the Bug
What size tires did you go to? It also depends on how hard you were mashing the pedal, it’s normal for me to hit redline and shift when getting on the highway out here in west Texas with the short on ramps. I’m on 40s and 5.38 gears, the ‘12-18 5 speed auto is a piece of “shift”. I have never liked the way it shifts and it’s just something I’ve lived with. Have your shop guy check it but don’t expect it to shift like before. I heard that this one company could reprogram the TCM and make the 5sp less of a piece of shit. OSTdyno
 

Primo82

Caught the Bug
Ok. Thanks for the info. I'll give them a call. I've been looking at the bluetooth OBDII adapter and jscan app as well, might just pull the trigger and check it out myself.

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I don't think an OBD2 tool can be used to change the programming. There are specialty flash devices for that. Maybe the more expensive tools, but I'm guessing that bluetooth one won't do what you need.
 

jesse3638

Active Member
I don't think an OBD2 tool can be used to change the programming. There are specialty flash devices for that. Maybe the more expensive tools, but I'm guessing that bluetooth one won't do what you need.
I believe the jscan tool will allow you to set your gear ratio. I thought that if they didn't change ratio the vehicle would go into limo mode? I may be wrong though.

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AgBass01

Member
I don't think an OBD2 tool can be used to change the programming. There are specialty flash devices for that. Maybe the more expensive tools, but I'm guessing that bluetooth one won't do what you need.

I believe the jscan tool will allow you to set your gear ratio. I thought that if they didn't change ratio the vehicle would go into limo mode? I may be wrong though.

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Correct, the jscan app will allow to change gear ratio. I was under the same impression that it would go into limp mode if they didn't do it.

As far as tire size, I haven't upgraded yet. I currently have 32s but am going up to 35s at some point.
 

Primo82

Caught the Bug
I believe the jscan tool will allow you to set your gear ratio. I thought that if they didn't change ratio the vehicle would go into limo mode? I may be wrong though.

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Ok, I haven't had to program mine. I had a buddy go up to 35s and he bought one of the flashcals I think. I don't think it'll put it in a limp mode. I think your shift points will be wrong, which sounds like what you got!

Also, they may not have programmed your tire size, or maybe overwrote tire size when updating your gear ratio. If you had a shop do the work I'd take it back and make them fix.
 

sipafz

Caught the Bug
Regardless of all this, the OP should get his own programmer and not depend on someone else to do it right.
 

jesse3638

Active Member
Correct, the jscan app will allow to change gear ratio. I was under the same impression that it would go into limp mode if they didn't do it.

As far as tire size, I haven't upgraded yet. I currently have 32s but am going up to 35s at some point.
Ok sounds like tire size is more the issue. The small tire you are running will cause it to run higher in the RPM range due to the lower gears you had installed. Being that you didn't change tires adjusting for the new gears should have the shift points where they need to be if it was already corrected for the 32's. In my research 4:56 would feel right for 35's like 32's feel right for 4:10's.

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AgBass01

Member
Ok sounds like tire size is more the issue. The small tire you are running will cause it to run higher in the RPM range due to the lower gears you had installed. Being that you didn't change tires adjusting for the new gears should have the shift points where they need to be if it was already corrected for the 32's. In my research 4:56 would feel right for 35's like 32's feel right for 4:10's.

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That's what I was wondering. I doubt it was corrected for the 32s, I bought it used with the 32s on it already.
 

AgBass01

Member
You know Bubba at Exodus Jeeps is about an hour from you? not sure what shop you used.

Yes, I used a well respected local shop that has helped me out on numerous occasions with little issues here and there.

It’ll drive like asshole but it won’t always go into limp mode.

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Good to know Bubba. Sounds like I just need to bite the bullet and get a programmer of some sort and get my tires done sooner rather than later.
 
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