[ldherrick]

Hi all,

I'm having an interesting lope/surge/buck on startup after the truck sits for a few hours or overnight.
Basically, the truck will fire right up like normal but then it will lope bad for 30s or so and progressively smooth out. No codes, no messages from the computer, and otherwise the truck runs just like it should. Has anyone else had this experience or have any insight?

Things to note:
- It's not the grid heater drawing current, this will happen cold or not although worse when it's cold (10-30°F)
- Fuel filters were both changed before this started. First time this happened was about a week after the new filters
- After driving it around for the day, this doesn't occur on restart (ie, go to the job site, work for a bit, then start the truck again and leave)
- No smoke observed when this is happening (yes it's stock, I know the dpf/scr may mask any if it's there)

 

[Den52]

It sounds like maybe it is loosing prime and having to get the air out of the system so smooth out. Did this start right after the new fuel filters?

 

[ldherrick]

There was a span of about a week between the filter changes where this didn't exist, plus I've checked both filters and the drain valve on the fuel bowl again.

The caveat is that it starts like normal, the surging/loping starts right after that.

 

[Raspy]

Mine does it too. But not only for 30 seconds after startup, also when warm.

I fix mine with a bottle of Power Service. That takes care of it for 1-2,000 miles, and then it comes back. I don't know why it does it, but I'm sure it has nothing to do with filters or losing prime. It also doesn't seem to matter if I run it hard towing, or easy around town.

 

[ldherrick]

Raspy, are you just using the regular diesel kleen in the grey bottle? I'll give it a go and post up any changes.

With that in mind, what are the odds of the fuel rail pressure relief valve sticking/opening and the power service is lubing it up enough to work for 1-2000 miles?

 

[Raspy]

The last couple of bottles I got were the white bottle.

I don't want to overthink this, or speculate on the relief valve. Clearly, the fuel can make a difference, as it does on mine, but I'm thinking it's an electronic or programming glitch. The last few tanks of fuel were winterized, as we were travelling in cold weather and towing, but it happens with winter or summer fuel. Running the truck easy or hard seems to make no difference. It's been about 2000 miles since I added anything and it is running fine. It was about 20 degrees at about 6,000 ft elevation the other morning. Ran fine. Two weeks ago we were in Death Valley at about 2500 ft, towing, and it was hunting on cold startup.

I'm also deleted and running the lowest level tune. It has never been raced or run with a high horsepower tune. The EGR is turned off.

So, I don't know and I'm not worried about it. It's just a minor annoyance that I would not expect from Cummins. And I can fix it for a couple thousand miles with a shot of elixir.

 

[K9Kodi]

does it sound like the exhaust break is on?
if you were to drive it with this lope what happens? i can't find it to save my life as i'm getting ready for bed but i had some computer issues where it would sound like that at start up and then surge when driving, i believe almost cut out, once warm no issues. i videoed it and there is a thread on it. a reflash fixed it

 

[Kentuc77]

If you sure its not eclectic or grid heat Check your fuel pressure before the cp3. And check the rail pressure to see if its loping with the idle. If you have no gauges or computer to check these numbers you can also cycle the key several times before you start it cold see if there a difference. Or when cold cycle the key and then open the air water valve on the filter under the bed the the fuel sould spray out with a little pressure if not and its just trickling you have low pressure and probably air. Check the fuel pump. If pump press looks good start with FCA easiest to change then pressure relief but they both should trough a code.

 

[ldherrick]

Updates,

Truck went back to the dealer and shockingly they came back with "We couldn't find anything wrong, this is normal for these Trucks"...BS as usual.

SO, still no codes/messages, and a few tanks of Power service had no effect.
The weather here has gotten warmer, which has made this problem noticeably worse...
- When it's 40°+ degrees out and the grid heater does not cycle, the lope is significantly worse and lasts longer (about 2 minutes of waiting for it to stop)
- Once the lope goes away, when I shift it into drive the lope comes right back and doesn't go away unless you take off down the road
- When you take off down the road, you can feel the truck surging (I can feel my weight shifting in the seat at steady throttle).
- Once warm though these problems still vanish and the truck feels normal again

Fuel Pressure
- I have tried priming the truck before starting, no difference. I don't have gauges but you can hear the pump building pressure

Exhaust Brake
- It does not feel like the brake is on. I typically cycle on the exhaust break on cold mornings and it is working properly.
- If I cycle on the exhaust brake during high idle, the engine will "kick" or miss here and there. Not constantly.

Fuel
- I've used several different high volume stations with different suppliers to see if fuel is making a difference. NO change between fill ups.

I'll try to upload a video I have of this as well.

 

[ldherrick]

Link to Video

https://youtu.be/Z6S5qR63YoA

 

[140M3]

My truck started doing the same thing at 110,000 miles+/-. I replaced the FCA, and the loping ceased.

 

[smokenoise]

Mine does this as well and it is a 2013 with 238k miles. To me it just sounds like a cold diesel building up cylinder temperature. Once the engine starts and the “warm” air from the grid heater is gone it starts mis firing until the cylinders are warmed. It’s just normal cold compression ignition engine operation. My 2007 5.9 would do it to but for a lot longer since I didn’t have a grid heater on it.

 

[Bbeaudet]

My truck started doing the same thing at 110,000 miles+/-. I replaced the FCA, and the loping ceased.

What is an FCA currently having the same issue

 

[IH8CALI]

What is an FCA currently having the same issue

It stands for Fuel Control Actuator (see below). Mine's done that for years, it's annoying but i'm not messing with it until there's a larger issue or the truck tells me somethings wrong. I gave up on parts throwing a while back.

'07.5-'24 Dodge Cummins Diesel Fuel Control Actuator

Located on the side of the high pressure fuel injection pump, the electronic fuel control actuator for the Cummins 6.7L engine is the metering valve of the fuel system.

www.genosgarage.com

 

[Bbeaudet]

Yeah i dont know what to do its done it since i got the truck drives me nuts! I hear alot of people throwing parts and nothing seems to get it 100% fixed i may try a couple parts my self just for the hell of it. Also heard the lift pump replacement may fix but i dont know if jumping that big is realistic

 

[IH8CALI]

I replaced the entire fuel module (Mopar 5145571AA) for an unrelated issue and no change.

 

[Bbeaudet]

Damn i may just let it ride out then

 

[IH8CALI]

Yeah I don't like it, but i'm not going to start chasing something. Been there too many times $$$.

 

[hray]

Have any you guys with the problem checked your valve lash?

 

[IH8CALI]

Have any you guys with the problem checked your valve lash?

That's actually on my list, probably won't get to it for a couple more weeks though. The wife's SUV needs shocks/struts, UBJ/LBJ, CVs etc. that'll keep me busy this weekend. I never thought valve lash would be related, but I will post what I find.