jgc2521

Hey, probably wednesday of this week, my truck started acting funny. Going down the interstate, holding at about 75mph my truck will start reving a little higher. say go from 2000 up to 2250or so rpm. The truck doesn't 'downshift', because with over drive off doing the same speed, the rpms read 3000ish. IT feels as if it is in the transmission, although i'm not 100% on this. almost like the torque converter is goin crazy. (but i don't know how they work so i could be completely wrong.

BTW, truck has 86k miles on it. and fluid was changed at 75k-ish. Also, problems didn't start until i changed pads, rotors,and front driver side hub about a week or 2 ago. Noise could possible be coming from there, either there or transmission.

Let me know what y'all think it could be, any help or opinions appreciated. Thanks,
jgc

BassAckwards

It's most likely your torque converter unlocking. With 4th gear being a .7:1 ratio, you have very little torque and hills and barely giving more gas will cause the converter to unlock basically acting as a lowering gear allowing your engine to turn faster than the tranny and make more torque. So basically what is happening is your TC is unlocking making your gear ratio lower wich is why your RPM goes up. But if your worried about your rotors and pads, make sure they arent draggin and causing your truck to think its going up hill because of the drag and making it unlock the TC.

Turkey Hunter

^agreed.

jgc2521

sounds logical, but it's doing it alot, more than it should. If it weren't my brakes what would cause it to lock and unlock... alot?

BassAckwards

It's hard to say if you don't have some way of knowing when its actually locked and unlocked, because I could be totally wrong about the TC locking/unlocking. My Edge Evo tells me when the TC is locked and its a nice feature to help you understand what makes it lock and unlock and lets you see that, "Hey! It didnt actually just shift down, the TC just unlocked"

So I'm only guessing unless you have a friend who has a Monitoring system (Not necessarily a tuner just a monitor that plugs into your OBDII port) that can show you when your tc is locked or not.

Maybe ask the place you took it to if anything they did could have caused the problem you are experiencing and see if they'll do a free check-up. They changed a lot of things that could have a draggin effect making your TC unlock because the truck thinks its going up hill or something.

But, at highway speed you should have plenty of torque at that speed if you just barely give it more gas the TC will stay locked, but in any gear if you give it quite a bit the TC automatically unlocks.

When do you experience this the most? Is it while speeding up or while holding your speed?

jgc2521

my friend has a scangauge, and i have a sct x3 chip that i can hook to my computer, i'm just not sure what parameter to look at. Also, i did the brakes/ rotors myself and have done it plenty of times before. I'm not saying that i didn't overlook something, but who knows. I also did the hub myself.

As far as when it happens. mostly at interstate speed. at constant throttle, even if cruise is on. And im in Louisiana, so its totally flat. I did notice it today going through town at ~35mph

BassAckwards

Well does your chip come with a monitor like the edge evo? Mine can show what gear your in and it has a little lock symbol to tell you when the torque converter is disengaged.

smlducks

jgc, i noticed mine doing that as well when going about 40 mph. my rpms were constantly moving 200 to 250 rpms up and down with a constant pressure applied to the gas pedal. im interested in these answers as well.

jgc2521

Mine got to where it would not shift into 3rd gear. I talked to another member on the here and his had the identical problem, and he said that he needed a complete rebuild. I haven't brought mine to the shop yet. been busy with school and work. When i do though i'll let you know. I don't want to scare you, but mine did the surging for 2-3 days maybe closer to a week i don't remember, but then it lost 3rd and 4th gear.