Engine stumbles off idle

[PacificNorthwestRVers]

My engine has been stumbling a bit when I ease into the throttle after idling. My normal driving style is to ease into the throttle vs. stepping on it. If I do step on it to accelerate quickly, then it behaves normally, albeit with the usual lag. But, if I accelerate gently from idle, the engine stumbles once or twice before accelerating normally.

This has been going on for about a week, so I changed the fuel filters this afternoon (the dash showed 17% remaining). No change.

My scanner shows no codes have been recorded. The truck has 56,450 miles, about half of that towing our 5th wheel.

FWIW, my appointment for the CP4/CP3 swap is in August.

Any suggestions or ideas?

 

[Topzide]

Keep the fuel level in the tank above the 1/4 tank level to help in the cooling of the pump. Sound like it could be the air filter needing to be checked and/or replaced. Just ran across similar issue on a diesel tractor the was stumbling and not getting up to full throttle. Air filter needed to be replaced. Having to educate the owner a bit on the maintenance. He's still pretty new to having a diesel engine equipment. He's owned a 2nd gen 5.9 that he's let get away from him and needs a lot of TLC! Helping him with a notebook to keep track of when things are done on tractor! Then to set him up with a binder to keep thing straight with the truck.

 

[Ozymandias]

I don't think so, the airfilter is monitored through the ECM.

Do you use AlfaOBD or just a generic scanner?

If there is a stumble the ECM will know about it, every single combustion event is monitored.

 

[PacificNorthwestRVers]

• The fuel tank is full. It rarely gets below 1/4 tank. FWIW, I have a 50 gal auxiliary tank that transfers fuel to the main tank via a pump and dedicated fuel filter.

• I doubt it's the air filter. I inspected it two weekends ago, just before pulling our 14,000# 5th wheel 600 miles to Idaho and back from the NW corner of Washington, crossing several mountain passes at 65-75 up the 6% grades.

• It started immediately today, but then stumbled badly for 2-3 seconds. Drove it 30+ miles with slight stumbling when accelerating from idle.

• Generic scanner. I'm not familiar with the AlfaOBD. After checking it out at their website, I can go Android or PC. I guess Android uses an interface and Bluetooth while the PC version uses a bypass. Suggestions are welcome!!

 

[Topzide]

With AlfaOBD you'll still need a security bypass cable whether you use Bluetooth or PC. It's a wise investment for your truck in the long run! Allows you to scan codes and remove them. You'll like the feature that if you go Bluetooth, you'll be able to check lights on the trailer by yourself! Many great features with AlfaOBD. I've used mine countless times on my '14 and FIL '20 with cable. Keep digging at the issue and it will revel itself! Enjoy the time in the 5th wheel.

 

[Ozymandias]

Doesn't sound good, maybe your CP4 is on its way south. I'd see a dealer right away now.

AlfaOBD is best on android, I use it with a tablet device. If you don't have one, a cheap 100$ version is plenty.

 

[PacificNorthwestRVers]

Let me double-check what I need for AlfaOBD . . .

1. AlfaOBD software on my Android phone or tablet
2. Bluetooth adapter

http://www.obdkey.com/obd_bluetooth_info.asp​

3. Bypass cable

https://www.kaodtech.com/product-page/security-module-bypass
​

 

[Ozymandias]

Most of us run the https://www.obdlink.com/products/obdlink-lx/ but almost any Bluetooth dongle will do it.

ObdLink comes with their own free software which we do not use for the RAM, but it's okay for any other vehicle that might be around.

Bypass cable is right.
You can get all the stuff also on Amazon Marketplace.

 

[Ozymandias]

The AlfaOBD software you download directly in the Playstore (nowhere else) on your device, it comes as a free software with an "ingame" 50$ purchase for the full functionality.

 

[PacificNorthwestRVers]

Thanks guys! Everything is on order. Time will tell what I discover.

 

[PacificNorthwestRVers]

Great news!

I called the local dealership and was lucky enough to get an appointment for the following day to troubleshoot the problem. The service writer talked to the tech about my issues, and the tech also thought the CP4 pump could be the cause of my truck's stumbling. Another customer had just cancelled his appointment for the CP4/CP3 pump replacement, so they were able to do mine over the next few days instead of waiting till August for my appointment.

I got the truck back last Tuesday, so it's been a week. . . the truck runs awesome again!

I've included a photo of the repair order that shows the warranty time and charges for the job.
As usual, the TDR folks were spot on. Thanks!