Confirm My Suspicions?

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
After chasing many things I think we finally found my issue. I'll start from the beginning and see what you guys think.

Initially I was plagued with a FPR issue P0089. It would spike rail pressure at idle and cause loping / surging. That issue seems to have disappeared after I messed with the wiring hoping it was a bare wire / grounding issue. Truck ran fine for a few weeks. Drove to Tennessee and it felt like the converter was slipping. It would smoke badly and rev, but would not downshift and go. Fast forward, I bought and installed Ben's lockup switch hoping it was the tcm or converter somehow. Thought the switch worked and it does, however I am still plagued by the same issue. Today I put the truck in tow/haul & auto on the switch...it got to 3rd and I punched it. Truck revved, smoked, and wouldn't shift. Spoke with Evan @ Limitless and he suggested it could be the FPR. Got home and did a short data-log and desired rail pressure was around 22000, but actual rail pressure was about 12000.

Could I have gotten a bad FPR initially and it been masked by tuning? Or indeed be a wire / ground issue?

It IS a new pump ~6 months old / 3000-4000 miles on it. Modified lbz from Fleece. Any thoughts / opinions / ideas?
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
I would hope they are. Can I check those with Imperial? There's no fuel in my oil. Injectors were put in the same time the cp3 was. 30% overs from LDS. Reman lines also.
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
I dont have any codes now with the truck acting up. Service engine light comes on before I start the truck but there's no codes then or when its running.
 

duramaxnate

Professional Amateur
Feb 18, 2014
513
0
16
32
Norco, CA
www.mcfooracing.com
I have heard some people unplugging their ECM for a bit and doing the same with the big engine harness plugs. I have a truck seeing me friday with this same issue hopefully this fixes it.
 

c20elephant

C20ELEPHANT
Apr 25, 2013
2,065
0
0
Phoenix, Arizona
Disconnect BOTH sets of battery cables, clamp one pair together and then the other two for about a minute. This cleared an ECM code I could not get rid of after flashing it, no problems since and it's been a little over 2 years.
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
I'll get a maf reading. That sounds odd. Clamping battery cables together. Does it sound like an ecm issue or fpr?


Sent from my iPhone using Tapatalk
 

clrussell

pro-procrastinator
Sep 23, 2013
5,928
399
83
Who's tuning? Lbz pump on lb7 could be tuning issue. I'm sure your injectors are good considering the age and where they came from.

Your rail pressure is way low and it'll make it run like crap and not shift correctly as Evan said.
 

Dozerboy

Well-known member
Jun 23, 2009
4,917
496
83
TX of course
You can log the FPR voltage maybe that would show you if there was a wiring issue? Unplug your FPR to max out the RP and log it to see if you have good RP at idle. Check the fuel return of your injector and cp3.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
Russell, you're correct sir. Everything should be running correctly. I have GDP tuning from Jeremy pierce. They're also Gorilla tuning. We just tested it 30 min ago and it spiked to 26000 then dropped to 4000. That's what my buddy said who was looking at the computer.

Dozer, I'll give that a try.


Sent from my iPhone using Tapatalk
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,743
5,911
113
Phoenix Az
You can log the FPR voltage maybe that would show you if there was a wiring issue? Unplug your FPR to max out the RP and log it to see if you have good RP at idle. Check the fuel return of your injector and cp3.

Sent from my SAMSUNG-SM-G900A using Tapatalk

following along with this, id unplug it and go for a drive as well with a WOT run and see if rail still drops that low. its not going to sound good at idle or low rpm till you get into it but it should be fine for a quick test while you log
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
I will give that a try. I also got in touch with Jeremy who tuned it and he suggested a rail plug. Since the fpr isn't fluctuating. It's only losing rail over 70% throttle.


Sent from my iPhone using Tapatalk
 

clrussell

pro-procrastinator
Sep 23, 2013
5,928
399
83
Lb7 doesn't have a rail plug persay..


I mean they do but its not like a lly + and alot more difficult



Did this just start or has it been since the new pump?
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,743
5,911
113
Phoenix Az
I will give that a try. I also got in touch with Jeremy who tuned it and he suggested a rail plug. Since the fpr isn't fluctuating. It's only losing rail over 70% throttle.


Sent from my iPhone using Tapatalk

its possible it popped. they very RARELY ever pop but once they do, its very easy for them to keep opening up. only way to stop them from doing that is a new FPRV or weld it shut. test to see if its opening via a bottle test (going to be some work to get down in there and get the line free to test) but that will tell you. if you have nothing in the bottle, its not the FPRV. you should also be seeing it pop open if you pull the FPR connection from it and run the cp3 to max pressure. if the log does not show a drop in pressure, its not the FPRV
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,735
804
113
Texas!!!
its possible it popped. they very RARELY ever pop but once they do, its very easy for them to keep opening up. only way to stop them from doing that is a new FPRV or weld it shut. test to see if its opening via a bottle test (going to be some work to get down in there and get the line free to test) but that will tell you. if you have nothing in the bottle, its not the FPRV. you should also be seeing it pop open if you pull the FPR connection from it and run the cp3 to max pressure. if the log does not show a drop in pressure, its not the FPRV
He did say his rail pressure spiked to 26k the dropped to 4k when he unplugged his regulator, but he would be seeing a spike and sharp drop in pressure in a datalog if it was opening under power.
 

mcsc

New member
Nov 8, 2015
25
0
0
Greenwood, SC
Josh, I didn't unplug the regulator when it spiked. I've not gotten that far with diagnosis. That spike and drop was under load and then backed out during datalogging.


Sent from my iPhone using Tapatalk