I've been wanting to ask for awhile always forgot once I got out of the truck. When I am stopped and then accelerate to lets say 50mph, heres what happens RPM wise. My truck idles at about 1200-1500 and then could go to about 2300 but I usually left up my foot at 2000 because I can hear the engine and let it shift. Now its in second gear. This is the weird part, right after it shifts to 2nd, it shifts to 3rd within a matter of literally 1-2 seconds. Then when I get to about 37-40 on my unaccurate speedometer I lift again to shift into OD. Does anyone elses truck shift from 2nd to 3rd that quick as well? Could it be because of the size of my tires with my 3.55 gears or something else?

 

Are you serious about the 1200-1500 idle? I looked at mine yesterday and it sits at 650 or so. Your's seems pretty high.

About the quick shift ... yeah, mine does that, too. As you're letting off the gas, the PCM sees it and up-shifts the tranny. It won't down-shift it unless it sees you input a request for passing gear (throttle position[down] + rpm[down] + speed[down]). As these three things cross a certain point, the PCM will call for a down-shift. Of course, it will also down-shift (eventualy) as vehicle speed is reduced but you knew that already.

 

Yea that can't be right idk what I was thinking when I typed that. I think its more around yours, I think I wrote that because I was thinking of the RPM when my truck is in OD, I'll find out what it is exactly tomorrow.

 

As a diesel man, I ask a question too. Do the 1/2 tons have a lock up converter? If so, that may be giving you the fast shift. Slightly letting off the pedal as the truck accelerates will make the tc lock up occur sooner (at 30mph and above?). This could very well cause that fast 3 or 4, to lockup shift that you are sensing. Stay on the pedal and let the converter catch up on it's own. Don't let up on the pedal either. Just normal acceleration.

Now see if the shifts are a little further apart. If the shift is still fast, maybe it's time for a look at the valve body.

Again, I am basing this on a lockup converter in your driveline.

I'll keep an eye out. I'm curious.

Good luck.

 

Yes, the 1/2-tons have a lock-up converter. I'm not certain but I'm thinking that the converter locking up is what they call OD. Someone please correct me if I'm wrong.

Phhhttt ... like I have to ask for it ...

 

Alright I'll give that a shot and post back tomorrow evening

 

Oh, excellent... This subject happens to be the exact reason I googled into this forum. Perfect.

We've been having precisely the same problem. Disregarding specifying RPMs and speeds, suffice to say that the transmission shifts all over the place, usually wrong. Almost schizophrenic, you might say. It's been driving us crazy.

Another twist is that we don't really care why. The question is, how to change it.

This question led us to the dealer, who frowned, scratched his beard, hmmmd and hawed. It is programmed to do so electronically, he said. There are six electrical leads leading into the transmission, all hooked up to sensors detecting and reporting values for RPM, torque, pressure and so on to the mother computer.

Okay.

So, if I may ask the informed brethren of this wonderful forum: How can the transmission's shift points be altered?

Thanks in advance.
Camz.

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Brief polite introduction... How do you do, pleased to meetcha... New guy here... Very informed on technical things; have a fully equipped machine shop and many years of experience. However, the door isn't big enough for a car, so not very much experience working on them.
The truck by the way, is a 1999 D.R. 2500.

 

Torque converter lock-up will occur in both 3rd gear and in Overdrive.

One maintenance item to consider is adjusting the bands on the transmission. This should be done every 30,000 miles. Since you have to drop the pan, you can add new transmission fluid at this time which is also a recommended at this mileage interval. Band adjustment may help with the shifting issues. You can do this job yourself or go to a garage to have the work done.

The shift points are controlled electronically. The governer pressure solenoid measures the governer pressure and sends the data to the PCM which bascially tells the transmission when to shift. There isn't much you can do with this setup. There is some mechanical adjustments which should be checked to eliminate "play" in some of the linkage to the solendoid. See the following link on how to check this adjustment: http://www.v8performance.com/tipsandtricks.htm#TVCable

You can control the shifting somewhat by how you drive. As mentioned earlier, harder acceleration will cause later shifts. Another thing is to lock out OD using the button on the end of the shift lever. Keep the OD locked out until you reach 55 mph or so, then let off the gas and switch the button to allow the tranny to go into OD. This allows a smooth shift into OD. By manually shifting it into OD at the higher speeds, it keeps the engine from lugging and improves acceleration. Also on my truck, it seems to keep the tranny in 3rd gear torque converter a little longer, smoothing out the shift sequence.

 

The tranny shift points can be altered via software reprogramming.

Yes, the 1/2-tons have a lock-up converter. I'm not certain but I'm thinking that the converter locking up is what they call OD. Someone please correct me if I'm wrong.
Overdrive is seperate from lockup. If I remeber correctly, over drive is where one turn of the trannys input shaft overdives the output shaft. For example for every rotation of the engine, the rear wheels might be driven 1.5 revolutions. Those numbers aren't exact, they are just for example.

The torque converter locks up in third if OD is off, and 4th if OD is on. (Do the dodges have 5 speed autos yet?). In theory, when the tc locks-up, the engine and tranny input shaft are mechanically linked. Now you have a 1:1 ratio. Out of lock up, the tranny is being driven by the fluid portion of the tc.

That tc is pretty amazing for what it does. It's too bad that Dodge didn't beef theirs up a little more.

Good luck.

 

Well how about this...say sometimes when you take off from a stop light, the tranny shifts from first to second then for a second or so it shifts back to first and kinda jumps. Then it shifts right back into second and then smoothly into all other gears. It only does it occasionally. The bands were tightened by my dad while I was in tech school a little over 2 yrs ago b/c it was shifting in and out of overdrive goig along at about 60mph until you stomped on the gas and made it down shift. Any ideas about that or is it related to the same problem other guy is having?