Strange Torque Converter ???

[buzzfx4]

So, I had something strange happen to me today with my torque converter. I'm not sure if its normal and I have never noticed it or there something wrong with the torque converter or the programer is telling the computer something fun.

I was driving through the northern lower Michigan where there are some good long 25-35% grade hills. I was traveling around 60mph and the programer with custom tunes was showing that it was in high gear and the converter was locked up. While going down some of these steep hills I would let off the gas so note to pick up to much speed. While costing down the hill the converter would unlock the second I let of the gas but about half way down the hill the programer would show that the convert re-lucked up, which you could feel. The funny thing is, that when it re-lucked up, the truck would be still in 4th gear and the truck would start to slow down though what I feel as engine braking....

I'm not sure if this a normal thing, (but I never really felt it like today) or there is something wrong computer/electrical or mechanically.

Thanks for any insight

[Longshot270]

I think this is normal. If you were going 60 before you started going down hill would that mean is locked back up around 70 or so? This happens to me when I'm doing 1/4 mile times or have a reason to go really fast. If I let off it has that engine brake feel until about 70, then the truck just rolls like it is not locked.

[Jackpine]

Are you sure the grade was 25-35%? I think the steepest I've been on was the road down into the Black Canyon of the Gunnison in Colorado, and I think that was 18%. I went down and up in 1st gear. You usually see runaway truck ramps on grades of 6-8%.

Anyway, if you don't have the cruise control engaged, the TC will immediately unlock when you let up on the gas, so the truck can coast and save fuel. On a grade steeper than about 4%, you are definitely going to speed up. At some point, your speed would be so great that the TC may well lock again and yes, when it does, you will feel engine braking.

My guess is, on a 25-35% grade you were well over 100mph very quickly! Maybe you hit the speed limiter and it reengaged the TC?

- Jack

[Longshot270]

Be nice Jack, he probably was going on a 15% grade but it felt like more. I've climbed up 40% grades and they felt like they were more than that because after my bumper all I could see was sky. (yes they were 40 because I measured afterwards)

[Jackpine]

Actually, I WAS being nice. But a 25-35% grade (or even a 15% grade) is going to cause you to speed up very quickly if you are coasting in 4th gear. If I don't drop my truck into 3rd, when I'm going down the 6-8%, 8 -15 mile grades here in Arizona, I speed up, cruise control on or not. And, I don't want to do that when I'm pulling a trailer (and I damn sure don't want to ride the brakes).

- Jack

[Longshot270]

Oh, I guess I figured that Il had grades like over here in the hill country. I have to climb a few 20* degree grades to get around over here. Why they built a town on the steep side of a hill is beyond me.