15' PW 1500 RPM Stumble

[coder]

Have you tried running the recommended 89 and switching to a different brand gas for a tank or 2 not? I am not sure if the will resolve the problem but it's usually good to try the easy things first. I added a screen-shot from this page form the 2016 owners manual for reference.

[Will]

Yall should go ahead with the highest octane in your area, I have ran 93 in mine since day one unless in a pickle. It looses power, sounds like shit and drinks 87 and the recommended is 89. Before I got a tuner for mine, I could hear the valves with 87, it didnt like it at all! With the tuner, I have tried the Diablo 87 mpg booster tune but still go back to 93 with Seans tune. Better mpg, better response, smoother running.

[adeluca73]

At that speed and RPM, I'd think you were feeling the torque converter unlocking. An easy test is to turn off the radio, roll down the window, and repeat your test condition--if it's the MDS, you'll be able to hear a noticeable change in engine and exhaust signature. Mass flow rate (m_dot) will instantly decrease, exhaust velocity will decrease, and the butterfly valve in your exhaust will probably close with the reduction in m_dot--all audible clues.

[Sweet5ltr]

You would think so, but I should have also noticed an rpm decrease/increase if the torque converter had anything to do with it. No fluctuation in RPM, just heavy hesitation and bucking. My first course of action has been to dump some higher octane fuel in it at another station. This may very well be the cause of the issue all together.. 'light pinging is okay' via the manual, wow, that's a first.

[Ed1774]

My 2015 does the same thing. It will surge at low rpm driving as described here. I run 89 octane all the time. I personally believe it is coming from the torque converter hunting between lockup and non lockup.

I find my truck has a few quirks and this is one of them. Kinda wish I kept my 2010 5.7 2500.

[Sweet5ltr]

Update: 20+ gallons of 93 went into the truck yesterday, very little to no difference in performance or resolution to the issue. Actually, it was pretty dramatic this morning. Truck held 3rd gear taking a corner at 8-12 MPH. In tow/haul+manual mode, it stuck itself in 4th gear from 30-60MPH, not changing to 5th under light and even no throttle. I drive 45 minutes to work, and the truck still wouldn't shift into 6th in tow/haul + manual mode. I'm starting to think it just needs a seriously adjusted transmission tune (or a reflash at the very least), but going to take it to the dealer (hopefully tomorrow) and start my saga with the service department. My cruise control switch hasn't been working so it won't be a wasted trip for that at least. Tons of identical 'shudder' threads out there with the 6.4/66rfe trans combo Some are saying the problems go away after a reflash, others are saying that the dealer states its 'normal'. Give me a break, my 727 shifts like glass compared to this 66rfe.. lol

[Will]

I can't make mine stay at 1500rpm at 20mph. With any throttle at all, it downshifts and jumps up in rpm. I'm still thinking it's trying to hold in too high of gear. Hopefully a reflash or transmission tweak for the dealer will clear it up for yall.

[waldo]

Doesn't cost anything to disconnect the battery or pull the PCM fuse for a while, then go out and drive it hard to see if it relearns and acts differently.

[Sweet5ltr]

Yes, I could disconnect the battery which would cause the computer to relearn and may/may not fix the issue.. and I would have already done that.. If it wasn't a 60k truck.. I want the problem corrected indefinitely. Without a doubt, that would have been the first thing I done if it didn't have the factory warranty in place. If only we didn't need to spend $1,000 just for an unlocked PCM on these 2015+ 6.4's in order to tune

[NickTF]

Doesn't cost anything to disconnect the battery or pull the PCM fuse for a while, then go out and drive it hard to see if it relearns and acts differently.

Yes, easiest suggestion by far.

[Reloaderguy]

Update: 20+ gallons of 93 went into the truck yesterday, very little to no difference in performance or resolution to the issue. Actually, it was pretty dramatic this morning. Truck held 3rd gear taking a corner at 8-12 MPH. In tow/haul+manual mode, it stuck itself in 4th gear from 30-60MPH, not changing to 5th under light and even no throttle. I drive 45 minutes to work, and the truck still wouldn't shift into 6th in tow/haul + manual mode. I'm starting to think it just needs a seriously adjusted transmission tune (or a reflash at the very least), but going to take it to the dealer (hopefully tomorrow) and start my saga with the service department. My cruise control switch hasn't been working so it won't be a wasted trip for that at least. Tons of identical 'shudder' threads out there with the 6.4/66rfe trans combo Some are saying the problems go away after a reflash, others are saying that the dealer states its 'normal'. Give me a break, my 727 shifts like glass compared to this 66rfe.. lol

Tow/Haul mode locks out 6th gear. If you use it you will only have fifth gear range. If you want to deactivate MDS you can use the lock out switch on the shifter. Set it to +6 and MDS won't come on but you'll still have the full transmission range.

[LagunaH1]

start my saga with the service department.

Sorry if I'm stating the really obvious here... sounds like you can reproduce the issue very consistently. That being the case, ask to take the service manager for a test drive and show him what's going on. In the past, this has helped me quite a bit.

Good luck dude

[Sweet5ltr]

Update: 20+ gallons of 93 went into the truck yesterday, very little to no difference in performance or resolution to the issue. Actually, it was pretty dramatic this morning. Truck held 3rd gear taking a corner at 8-12 MPH. In tow/haul+manual mode, it stuck itself in 4th gear from 30-60MPH, not changing to 5th under light and even no throttle. I drive 45 minutes to work, and the truck still wouldn't shift into 6th in tow/haul + manual mode. I'm starting to think it just needs a seriously adjusted transmission tune (or a reflash at the very least), but going to take it to the dealer (hopefully tomorrow) and start my saga with the service department. My cruise control switch hasn't been working so it won't be a wasted trip for that at least. Tons of identical 'shudder' threads out there with the 6.4/66rfe trans combo Some are saying the problems go away after a reflash, others are saying that the dealer states its 'normal'. Give me a break, my 727 shifts like glass compared to this 66rfe.. lol

Tow/Haul mode locks out 6th gear. If you use it you will only have fifth gear range. If you want to deactivate MDS you can use the lock out switch on the shifter. Set it to +6 and MDS won't come on but you'll still have the full transmission range.

Yes, that is what I expected. Didn't have an opportunity to look through the manual yet. MDS has been ruled out. It's definitely a trans issue.

[Sweet5ltr]

start my saga with the service department.

Sorry if I'm stating the really obvious here... sounds like you can reproduce the issue very consistently. That being the case, ask to take the service manager for a test drive and show him what's going on. In the past, this has helped me quite a bit.

Good luck dude

Thank you,
It's a common problem, just no sure fix from what I've been reading. I'm sure many members have had the same experience with this transmission, just may believe that it's 'normal' for a HD truck.

I wonder if anyone has a Diablo tune for there 66rfe trans? That may be the ticket in the long run.

[LagunaH1]

Yeah, may be a bit of an up hill battle but please let us know how things turn out. I'd be very interested in hearing what happens.

[FirerescuePW]

FWIW, I would stop using forums to diagnose it and take it to the dealer. They can't fix it if you don't give them the chance. It's more than a little unfair to trash talk it and the dealer before they even know you have an issue.

[Sweet5ltr]

FWIW, I would stop using forums to diagnose it and take it to the dealer. They can't fix it if you don't give them the chance. It's more than a little unfair to trash talk it and the dealer before they even know you have an issue.

The service center is the last place I want my truck to be (personally). Forums are an excellent source of insight, especially considering the sheer number of owners experiencing the same problem, with no definite fix. It's always a 'saga' when you go to the dealer, my Z06 dropped a valve @ 30k miles.. Instead of installing a completely new set of valve springs, they replaced the single busted spring and tossed the valve cover back on (that took two weeks).. My Z06 also was towed 4-6 times on a flat bed due to a faulty 'steering column lock' module that GM had no fix for, just a reflash. I spent a few dollars (after figuring out I wasn't the only one with this problem), and purchased a bypass module that solved the issue completely.

My diesel 5500's that I recently had serviced, well, the last dealer tossed in a 'parts store' fuel filter that caused the truck to be dead lined within 1,000 miles. Headlight they replaced, that lasted 30 miles as they purchased a non-oem sealed beam with twice the terminal length into the plug and it grounded out on the housing. My new dealer replaced our 2,000 CCA battery with 2x 750 CCA batteries (close enough, right?).. You would expect to leave the dealer with 8x $1,000,000 vehicles that didn't pop up with two check engine lights and one with a dead battery after spending $16,000 to change the oil, top off the wiper fluid reservoir, diff fluids, and perform DOT inspections (these mechanics make $30+hr).. 20k generator, has been at another dealer 5-weeks for a starter replacement. Give the dealers a chance, they always look out for your best interest . Trust me, you're much better off doing 99% of things yourself as long as they are feasible and don't require much 'out of pocket' expenses (if still under warranty), and these forums (along with others) are a big help. I just want all my check boxes filled before I take it to the dealer, if it comes down to that. If a check engine light comes on, of course, take it to the dealer. If there is no check engine light, and the severity of the condition is intermittent, then it's a bit of a headache.

[Reloaderguy]

With your luck I'd get a bike.

[Sweet5ltr]

With your luck I'd get a bike.

I'm not too worried about the dodge dealership, they were great with my SRT! Can't say that about all dealers in my area, I would have owned a 14' PW but another local dealer attempted to tack on $5,000 in charges to the final financial layout than what we shook on/agreed to, and it was an 'auto show' only truck as well. Just want to try my best to identify the problem area to help the dealer expedite the process as it doesn't throw a code. I'm optimistic about it for sure. I've driven the truck nearly 1,000 miles in the past two weeks alone, so still loving it regardless of it throwing a shift tantrum I just broke down and disconnected the battery.. This should solve if its a TCM 'tuning' problem or mechanical problem with the torque converter/trans.

[adeluca73]

Torque Converter... Try my window down test, it's free, and will surprisingly provide some interesting data points...

[Sweet5ltr]

Torque Converter... Try my window down test, it's free, and will surprisingly provide some interesting data points...

I'll try that out.. I had it in manual mode/tow-haul this morning to rule out MDS.

Thanks everyone for the friendly advice so far.

[Sweet5ltr]

This truck is so funky, ran to 2500 RPM, stuck, and the torque converter started slipping.. Then like a terrible case of turbo lag, jolted up to 3,000 RPM (identical amount of throttle). I'm thinking this may be a converter problem, going to take it to the dealer..

[Zybane]

Please keep us updated!

My '16 PW does the same thing. I think it must be some programming issue. I have to purposely accelerate faster than normal just to keep it out of this stutter/bucking phase during light throttle.

I may have to take it to the dealer (cringe).

[Sweet5ltr]

Well Zybane,

I've been running the truck in tow/haul mode and the hesitation has been minimal in comparison to the 'ECO/PRIUS FIGHTER' mode that the TCM is programmed for. I'm at around 12.3'ish MPG driving around town on 91'ish octane with 100 miles left to go (87/93 blend). My best tank has been 14 (pure interstate, truck empty, & 87 octane) and 13 (around town/Prius mode on 87 octane, *12.5ish on another fillup*).

I was only at 11.5 MPG before I started driving with tow/haul mode exclusively on this tank. So, i'm starting to think it makes little to no difference around town, except the truck actually performs other than bogs in 5th and 6th gear running 40 mph, causing way too much fuel/air to be dumped into the cylinder prior to it kicking down a gear and moving along.. I have to take it in to the dealer to have the cruise control switch replaced (no cruise also doesn't help MPG), so I will definitely talk to them about it then.

[Zybane]

Tested out tow haul mode (locks out MDS and 6th gear), and +6 gear shift selector setting which locks out MDS. Both modes still exhibited the problem.