Tow/Haul causes shifting and 'hunting' issues

[everittak]

I've had my 06 for 6 months now. Milage is great, normal driving is great, and towing with NO tow options selected is great. However, I recently hauled a car ~300mi with my car trailer (combined weight ~6k) and thought I'd use the tow/haul to help her out in the pass. Wrong. Both tow/haul modes hunted for gears, and the torque converter locks/unlocks. On one hill I couldn't push her past 55mph with the pedal mashed. After much frustration, I disabled the tow mode and drove home pleasantly at any speed I wished. Help?

 

[cerberusiam]

You have only one TH mode, the other is OD off. I cna understand the TC lock\unlock in OD off mode, not in TH. That should have been a much more aggressive shift and lockup strategy. Gear hunt should have been reduced in TH because it extends the shift points and you will need to use more throttle to get to the shifts.



What gears did you feel it was hunting for? Could what you thought of as gear hunt be the TC locking and unlocking in 2nd and drive?



When you could only see 55 mph up a hill what gear was it in and what were your rpm's?

 

[everittak]

The gear hunt was 3/4 in TH as was some of the TC lockup. In OD off mode it hung in 3rd and TC lockup/release was more evident and occurred quite often at each hill and terrain change. I didn't think to keep track of the RPM's/speed as closely as I would have like too. I can tell you that it wouldn't upshift on a hill and almost stalled the truck twice where it upshifted at the last moment (800 RPM or so). Needless to say, after all this mess, I took it out of tow and it pulled the 6k beautifully as would be expected - so the issue in my opinion is strictly with the TH/Lockout modes. I'm taking it in to the shop today to ensure that I have the newest flash and opti-idle enabled. We'll see if the flash can be updated and what it changes.

 

[everittak]

Oh, to clarify, not using TH/lockout was the aggressive good hauler. TH/lockout was waaay worse, soft, poor rpm management - the opposite you would expect.

 

[F-15I Ra'am]

When you hit a hill and it starts to hunt gears whether it's in o. d. or tow haul you need to shift to od/th lockout.

 

[cerberusiam]

The gear hunt was 3/4 in TH as was some of the TC lockup. In OD off mode it hung in 3rd and TC lockup/release was more evident and occurred quite often at each hill and terrain change.

My first thought is what speed were you trying to maintain and how steep were the grades? The TH program is really keyed to aggressive lockup and later shifting for acceleration but it will have an effect when you are on the bubble for OD. Under 70 mph its almost worthless unless you add enough power to minimize the speed drop to under 5 mph. Stock it will shift back and forth on hills and coast till it drives you crazy trying to maintain a 60 mph speed. Its all about fuel curves and TQ management that is built in and that is NOT conducive to OD operations under 70 mph.



Mine did the SAME thing stock, drove me nuts towing on secondary roads and trying pass slow moving vehicles in those conditions. If it wasn't in OD and lugging it was in drive up against the rev limiter from the sloppy TC.



A good TC, a Smarty, and an OD lockout box fixed that problem nicely.

I can tell you that it wouldn't upshift on a hill and almost stalled the truck twice where it upshifted at the last moment (800 RPM or so).

You mean downshift? One other oddity you need to watch out for is how you use the accelerator in conditions like this. If you pin the accelerator to the floor it causes a no downshift scenario and it will lug waaaaaayyyyyy down before it downshifts to drive. If you stab thta throttle hard and NOT go any farther than 3/4 to 7/8 throttle you should get about a 3 count and if it doesn't accelerate it will downshift. Don't use cruise either cuz the cruise pins the APPS wide open and it just lugs and lugs and lugs... ... .



I fixed than little problem with the extra power and a trans rebuild to fix the OE shortcomings.

I took it out of tow and it pulled the 6k beautifully as would be expected - so the issue in my opinion is strictly with the TH/Lockout modes.

It could very well be an issue with the VB and the gov pressure sesnor\solenoid that is throwing things out of synch. I hope wherever you are taking it is familiar with the problems or it could be long frustrating process to get acknowledgement there is a problem.



Good luck.

 

[everittak]

cerberusiam - I think you're hitting this on the head. What you describe is very close to what I'm attempting to convey. And yes, I meant downshift. So if I understand you correct the ecm and the fuel/shift map is created to work better at 70+ rather than ~60 where you get the best milage? If so, that seems crazy to me, not your claims mind you, but that they would design a truck with that in mind. We all don't live in flat terrain with perfect highway. Alaska is filled with rutty frost heaved roads that wind up and through beautiful mountains. 70+ is not something you'd want to tow at up here. My old 94 5 speed was perfect for this - 62 mph towing getting ~ 19mpg. I loved it. This mega gets pretty good milage, but the tow performace sucks right now. Anyhow, I'm suppose to get it back from the dealer today after having an audit and flash of any/all firmware updates. I'll see if it helps as some here and there have claimed. Oh, now that you have the smarty ect, do you have the most recent flashes?

 

[cerberusiam]

That is one of the biggest bugaboos with the 48RE and towing with the higher gear ratios, big jump to OD and at certain speeds its a pain. A much better combo is 4. 10's and a 33-34 inch tire but then the mileage suffers. The stock configuration leaves a lot to be desired at times with the TH program.



To a point you can play with that and get it to hold gears better but that means mods tot he trans. A tighter TC helps a bit to minimize the cutaway feelings and use the TQ better. A DTT shift enhancer and tweaking on the TTVA motor will yield some different results also.



The biggest differnece I have found is the Smarty on SW4 and TQ management 3, and a little timing. You get better fueling at less throttle so the ECU sees less APPS movement so it doesn't hunt as much in the lower speeds. If I can maintain 60-65 and go easy with the throttle I seldom have issues with under 10k towing even in rolling hills. I may loose 6-7 mph on steep grades but alot less on smaller and it will hold OD and pull much better. At 15k its gets to be a little harder but it is doable.



Marco is really good about making sure the Smarty has the latest updates to the OS available for download from the MADS site. After I got the Smarty I quit having the delaer do the flashes becuase most of them were worthless anyway, especially around the trans control. With all the emissions laws changing these flashes are getting a bit dangerous as far as changing performance. The last time I did not threaten the service manager with dire results I got the stupid out of park alarm. #@$%!

 

[MAshley]

Well I just shift down to 5th when needed and then back to 6th once the hill is done. Oo. Sometime I need 4th but thats when traffic is bad. #@$%! Anyways I recon this is yet another reason no to buy a automatic. :-{}



Not trying to prompt a debate per say just feel bad in decades of building trucks they still can't make a automatic work.



Dave



06 3500, 4x4 G56

 

[cerberusiam]

Well I just shift down to 5th when needed and then back to 6th once the hill is done. Oo. Sometime I need 4th but thats when traffic is bad. #@$%! Anyways I recon this is yet another reason no to buy a automatic. :-{}



Not trying to prompt a debate per say just feel bad in decades of building trucks they still can't make a automatic work.

The same problem exists with the current crop of manuals, one OD gear and a big jump. A 6 speed with only one gear above direct is still short on gearing. Only under max loads do the 5 gears at or under direct give you an edge, the rest of the time we are skipping gears upshifting and still grabbing for 7th at times. :-laf



The only difference is with a manual you MUST select it, with an auto you have a choice.



The 48RE is really a stop gap measure and it definitely takes some tweaking and getting used to but once one learns its idiosynchracies and applies a few fixes its every bit as capable in most if not all situations. The Cummins TQ will overcome a lot of the shortfalls. Stock suffers badly from NVH initiatives but it has come a long way from the 46RH's in the 1st gens.



Now, with the release of the 68RFE Dodge HAS an auto that is really good. With 3 gears under direct, 2 over, and lower 1st gear it is really well suited to an I6 TQ curve. Auto shift works well and the manual mode gives operator control of the gears. The only thing left is a reasonably priced conversion kit to put them behind the 5. 9's.

 

[everittak]

Dealer says my trucks almost done, but added . 5 hour onto the 2 hours quoted to re-cal the tire/speedo to 285's per my request. I though that was a simple selection in the menu and he said, 'no it requires math for gear ratios and stuff'. Am I getting taken for an extra . 5?

<as to the tire size for the above transmission thread, I don't have them yet but buying 285's very soon>

 

[cerberusiam]

Am I getting taken for an extra . 5?

Pretty much, he is full of crap on how hard it is. Its a 30 second input. Now if you had a Smarty you could adjust yourself as many times as possible.

 

[MAshley]

Yes full of it. My dealer actually showed me some of the options and one was tires. . I recon he would have to do math between 285 and 33 inch tires and I recall it was all listed in the computer as 30 31 32 33 34 ETC for tires sizes ... but lets face it any mechanic with a brain would allready have that listed down somewhere or know it by hart. But take it all with a grain of salt, if it works better and he treats you well other wise let it slide, but if there anal about every little thing I was call BS.

 

[everittak]

Ok, so picked the 06 up from the dealer. I have not had a chance to tow with her yet, but at this point one could convince me that they replaced my transmission this afternoon. It's that much different. It finally drives how one would think this truck should.

Tow haul - messing around and drove her around town in tow haul for fun - much better. Higher RPM as expected and the TC stays locked. Thanks to all for the help everyone - I'm so glad that I don't need a new transmission/ecu/tc.

 

[cerberusiam]

What did they fix? Just a reflash or parts also?

 

[everittak]

Just a flash, no parts that I'm aware of. It's gotta be putting %40 more power to the ground than the flash it had on it which I'm assuming is the original.

 

[everittak]

Update, I just finished the weekend towing a 4 place enclosed trailer with 3 quads in it. Total weight, a hair shy of 5k. Not the 6k I was originally towing, but pretty close. Tow haul works beautifully now; she stills lugs a bit when overdrive comes on, but I've heard that from most 4spd owners. Again, thanks for all the help.