Slight Surge at highway speed

[SingleTrax]

Hey guys,
New to the board. Been looking all over for help.
Just made it back from a cross country trip. Truck has this slight surging while going through construction zones on the interstate at about 55-60 mph. Feels fine at 80mph. Feels like a misfire on a gas engine. Rpms never drop, speed doesn’t change, boost level stays consistent and rail pressure only has slight fluctuations. Does it on cruise control and off cruise. I can just feel it. No check engine light. I’m stumped as what to check.
Changed fuel filter, injectors have 1500 miles on them.
Any help would be great.
Thinking i need a pressure gauge to check lift pump pressure. Not sure after that...driving me crazy
Thanks!

 

[Crunch]

HTruck has this slight surging while going through construction zones on the interstate at about 55-60 mph. Feels fine at 80mph. Feels like a misfire on a gas engine. Rpms never drop, speed doesn’t change, boost level stays consistent and rail pressure only has slight fluctuations. Does it on cruise control and off cruise.

If you can describe this behavior as "bucking", I'd say that there is a good chance it is the APPS. That was the word I found that helped me zero in on the problem when searching online last year. Mine was doing the same thing, and was especially noticeable when using the cruise control. Same experiences you have. At higher speeds it seemed to go away. As per recommendations from people here, I replaced the APPS with a Timbo from Geno's and haven't had a problem since.

 

[cerberusiam]

MY 05 trucks have the APPS on the end of the accelerator pedal on the inside of the firewall, no Timbo emplacement for them. APPS problems will almost always set DTC's and a CEL if it is bad enough, OP needs to have the truck scanned to see if it has transient codes that are not setting a CEL as first step. 99% of the time the APPS on 05+ trucks is NOT the problem unless the harness has been pinched or mangled, they are pretty solid and resistant to the typical issues we used to see.

Looking at his signature he has BBI .5 injectors, that tells me it might very well be a fueling issue at low rpms. A set of stage ones in my truck exhibit the same behavior in a low rpm low load condition. Increase the speed\load or lockout OD and the problem disappears. It needs custom programming to be perfect. In rare conditions see this on my sons truck with a set of Bosch marine injectors, about the same delivery flow as BBI .5's. Not as bad as they 143 spray pattern but in certain conditions the CC will not settle completely solid until load and speed is increased.

2nd thing I have seen is a bad TCC causing this. Doesn't matter if it is high $$ built unit stuff happens and at low rpms the pressure is not enough or something else is wrong in the TC that causing a surge feeling. Seen it on aftermarket and stock TC's and it is an absolute beatch to find and diagnose because it acts like a misfire and\or injector problem.

 

[AH64ID]

What tuning are you running?

CC surge is common, but the cause behind it is seldom replicated without cruise. BBi’s are great injectors, but I’ll never recommend a set of 0.5’s to anyone for any use...and IMO all BBi’s need custom tuning.

Just to be clear I am not anti-BBi, just the 0.5’s. I’ve ran BBI’s myself and loved them, and would buy them again.. stage 1’s and larger only thou.

 

[SingleTrax]

I am running an edge cs2 on level 3. No codes come up on the edge or turning the key three times.
I’ve had this surge problem for a while. It was there before the firepunk transmission and the bbi injectors. Have been ignoring it but it was driving me crazy last week going down the interstate. Would like to try to figure it out before hooking up to the 5th wheel later this fall
I do have a slight oil leak on the front crank seal. Would oil on the crank position sensor cause a surge? Truck starts right up fine.
Thanks

 

[cerberusiam]

Have pulled the CS2 and checked to see if it is still there?

 

[SingleTrax]

I’ll pull the edge this week and see what happens

 

[SingleTrax]

Put the truck on stock setting then unplugged the CS2 from the obd2 plug. Hard to compare the driving around here vs the interstate but on one smooth stretch of road I could still feel the surging.

 

[PawsWet]

AH64ID - What was it about the stage 0.5 that you were not satisfied with? I’m not affiliated in any way, but BBi stage 0.5 (possibly reman) is my leading choice for an upcoming replacement set.

 

[AH64ID]

AH64ID - What was it about the stage 0.5 that you were not satisfied with? I’m not affiliated in any way, but BBi stage 0.5 (possibly reman) is my leading choice for an upcoming replacement set.

I haven't ran them personally but I've tuned a few trucks with them installed. They all haze at idle and light throttle. I was only able to tune the haze out on the guy that lives at sea level.

The 0.5 is nearly identical to the 1.0 but they limit duration mechanically. I think that leads to an inefficient pilot regardless of tuning. Under load they run great.

My money would be spent on Stage 1's with custom UDC Pro tuning.

On a side note I see a 1R-0750 in your sig. I recommend using a Fleetguard FF5814 next time you change filters. The FF5814 uses nanonet media, which I believe is the best fuel filtration media on the market.

 

[PawsWet]

I haven't ran them personally but I've tuned a few trucks with them installed. They all haze at idle and light throttle. I was only able to tune the haze out on the guy that lives at sea level.

The 0.5 is nearly identical to the 1.0 but they limit duration mechanically. I think that leads to an inefficient pilot regardless of tuning. Under load they run great.

My money would be spent on Stage 1's with custom UDC Pro tuning.

On a side note I see a 1R-0750 in your sig. I recommend using a Fleetguard FF5814 next time you change filters. The FF5814 uses nanonet media, which I believe is the best fuel filtration media on the market.

Next order will be the FF5814. Thanks
If I install stage 1, but take my time getting a tune (presently stock) there any reliability concerns? Haze at idle?

 

[AH64ID]

Next order will be the FF5814. Thanks
If I install stage 1, but take my time getting a tune (presently stock) there any reliability concerns? Haze at idle?

They should run just fine. Unless you're doing a bunch of heavy towing the added fuel shouldn't be an issue.

Shoot me a PM as you get closer to a tune and I can give you some more info.

 

[Prairie Dog]

My BBi .5's dont haze at idle but they look ofr any excuse to smoke at light throttle.
They were new, not rebuilds.