Surging at light throttle, not wanting to shift into OD

[El Capitan]

I have a 317k mile truck that only  sometimes, runs poorly in the lower gears. 11k miles ago, the original trans gave up the ghost. A friend of mine  built a trans with a triple disc Suncoast converter. Immediately the thing drove like crap. Stock truck, no mods, 2400rpm just to 2nd gear and BANG! shifted up into 3rd. And same into od. There's honestly no way to make this long story short. 

This last Thanksgiving, I spent it under the hood, doing the w-t ground mod and apps reset. So after it was done, I took it for a test run. Upon startup, idiot light indicated  batts=no charge. Stopped at the store 2 miles down the road realizing I never set the 150 amp breaker. Flipped it on, and idiot light went out. Figured huh! I must have done it correctly. Truck ran great. Thought I'd fixed it. After  a week or so, problem came back. Ok.... researching showed the ripple test. Yep! Had some number way over the acceptable tolerance, and so, replaced the alternator with a stock reman. Again, apps reset.  Fixed it for a few days. Ok time to get the initial fresh build, trans fluid changed. Brought it to a reputable shop, who told me that the idiot who installed it initially, never adjusted the av cable. When I picked it up from the shop, it drove better than it ever had. I was beaming!! Shifted quickly, and solid without the huge slam! So, although it shifts better,  I felt something else going on.  Although It shifts fine 1-2, 2-3 but sometimes in 3rd, between 30-35 mph (driving like a fuel consumption worry wart) surges and bucks it's way to OD. If I consistently drive like an A-hole, it shifts the way I imagine it's supposed to. Like butter. It's tough to get a good reading on this alternator and it's very possible I don't know how to use a DMM. I'm a builder not a electrical guy by any means. And I feel like its an electrical issue. My fuel pressure is at 14psi last i checked. And the intermittent issue is a constant when its wet condition driving. Any thoughts anyone? This is my first post. Thank you for all the help I've received through lurker mode!

 

[Tractorman]

17 minutes ago, El Capitan said:

Although It shifts fine 1-2, 2-3 but sometimes in 3rd, between 30-35 mph (driving like a fuel consumption worry wart) surges and bucks it's way to OD.

 

Try locking out Overdrive (4th) and see how it behaves.  The torque converter may locking and unlocking in 3rd gear.  Tthat combination, plus the shift into overdrive, may be masking the symptom.

 

- John

[El Capitan]

I've done that. Seems to make 0 difference. Even at 65mph however, i can hear/feel the slight hesitancy. No blatant rpm drop or surge. Also, no codes and i have run that diagnosis quite frequently. Never had any codes. 

[Great work!]

Hold break pedal up. Brake light switch can unlock the converter too.

[Tractorman]

It seems that when you reset the APPS, the symptoms go away for awhile.  That is indicative of an electrical problem.  If strays signals interfere with APPS output, the ECM will ignore the stray signals for awhile, but if they don't go away, the ECM will eventually treat the stray signals as valid.  

 

I would recheck your work that you did when you performed the W-T wiring modification - especially the ground circuits for the ECM and PCM.

 

Is there any accessory that has been added to your truck that could give off strong electrical fields?

 

- John

[LorenS]

Since it happens most when it's moist outside and also at very low throttle position, could it be that the APPS is just worn or dirty enough at that spot that it misbehaves?

[Mopar1973Man]

If you have a live data tool or a Quadzilla you could verify the APPS signal for abnormal spikes or drops. It's possible to fail within specs.

[El Capitan]

19 hours ago, Tractorman said:

It seems that when you reset the APPS, the symptoms go away for awhile.  That is indicative of an electrical problem.  If strays signals interfere with APPS output, the ECM will ignore the stray signals for awhile, but if they don't go away, the ECM will eventually treat the stray signals as valid.  

 

I would recheck your work that you did when you performed the W-T wiring modification - especially the ground circuits for the ECM and PCM.

 

Is there any accessory that has been added to your truck that could give off strong electrical fields?

 

- John

There is one connection I'm wary of. The 150 amp breaker, goes through the plastic housing of the device, into steel. Would the plastic act as a barrier of some sort? Electrically inclined, I am not. 

18 hours ago, LorenS said:

Since it happens most when it's moist outside and also at very low throttle position, could it be that the APPS is just worn or dirty enough at that spot that it misbehaves?

That's my question. How doninteat that? 

3 hours ago, Mopar1973Man said:

If you have a live data tool or a Quadzilla you could verify the APPS signal for abnormal spikes or drops. It's possible to fail within specs.

I dont have a live data tool. When it was in the trans shop for its first fluid change/spot check, it was hooked up to a live data scanner to monitor the trans and possible issues. Trans Guy said "probably electrical"

[Tractorman]

1 hour ago, El Capitan said:

There is one connection I'm wary of. The 150 amp breaker, goes through the plastic housing of the device, into steel. Would the plastic act as a barrier of some sort? Electrically inclined

 

I am not sure of what you are describing.  Most circuit breakers use a conductor with terminals at both ends.  The conductor and the terminals will be surrounded by a non-conductive material (plastic, composite, etc).  Is this what you are describing?  If so, there is nothing wrong here.

 

Post a photo of the circuit breaker.

 

- John

Edited February 3, 2023 by Tractorman

[LorenS]

20 hours ago, El Capitan said:

I dont have a live data tool.

I suggest getting one.  The ones I like most are the OBDLink brand.  I first read about them on this website and it was a great purchase.  The LX is all you need for these trucks.  I have the LX I keep in my truck and the MX+ for newer vehicles that I keep in my garage.
https://www.obdlink.com/products/obdlink-lx/

 

There are likely other, much cheaper brands that will do similar work, I cannot tell you how long they will last or the ease of using their app.  I can tell you that my LX has not had an easy life (dust, heat, plugged into the truck for months on end) and still works great, and the app works great - it's quite customizable without being so customizable you need a degree in programming.

[El Capitan]

On 2/2/2023 at 5:40 PM, Mopar1973Man said:

If you have a live data tool or a Quadzilla you could verify the APPS signal for abnormal spikes or drops. It's possible to fail within specs.

I dont have a live data tool. When it was in the trans shop for its first fluid change/spot check, it was hooked up to a live data scanner to monitor the trans and possible issues. Trans Guy said "probably electrical"

I will check em out. Actually makes alot of sense. Thank you. 

[Mopar1973Man]

Good reason to have a Quadzilla because that data can be displayed while driving and data logged for abnormal changes. Compared to my Innova tool only displays but doesn't data log.

[El Capitan]

6 hours ago, Mopar1973Man said:

Good reason to have a Quadzilla because that data can be displayed while driving and data logged for abnormal changes. Compared to my Innova tool only displays but doesn't data log.

So when i bought my tuner, I didn't have the 300+ hours of research into the diesel engine and supporting components  that I do now. The realization that my trans was now making the truck drive like a bucking bronco, sort of made me panic buy and install the tuner I have. I did do some.comparison before I bought it, but what I didn't know, was that it's absolutely a world of difference between the 2. Is there a specific model I should look at getting? 

[01_Cummins_4x4]

The Quadzilla tuner version you want, is this one;

 

https://www.dieselautopower.com/quadzilla-adrenaline-with-iquad-for-01-02.html

[5akman]

On 2/3/2023 at 2:32 PM, LorenS said:

I suggest getting one.  The ones I like most are the OBDLink brand.  I first read about them on this website and it was a great purchase.  The LX is all you need for these trucks.  I have the LX I keep in my truck and the MX+ for newer vehicles that I keep in my garage.
https://www.obdlink.com/products/obdlink-lx/

 

There are likely other, much cheaper brands that will do similar work, I cannot tell you how long they will last or the ease of using their app.  I can tell you that my LX has not had an easy life (dust, heat, plugged into the truck for months on end) and still works great, and the app works great - it's quite customizable without being so customizable you need a degree in programming.

So does this LX unit provide more diagnostic info than the Quad does? I realize that the Quad is primarily a tuner..

[LorenS]

19 hours ago, 5akman said:

So does this LX unit provide more diagnostic info than the Quad does? I realize that the Quad is primarily a tuner..

I really don't recall. The Quad doesn't read codes, as I recall. Can't say my truck has had any codes since I bought the Quad (knock on wood), so could be wrong on that.