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LML Cp3 Conversion Defueling Problem

34K views 33 replies 22 participants last post by  CPizzie 
#1 ·
My 2011 Sierra Denali LML's Cp4 recently grenaded and took my whole fuel system with it. Had all new injectors, filters and cp3 installed. The lines and tank flushed. Cp3 is an exergy sportsman by wehrli.

The truck is tuned with EFI Live by Kory Willis. I had all my tunes upgraded for the new conversion and pump by Kory. I had the guys at PPEI help me upload the new tunes to my auto cal.

So, after everything was installed and I flashed the new tunes all is not well. The truck seems to be defueling around 2000rpm. The rail pressure is around 21 Kpsi and injector rate timing is a bot +5. This happens at any speed. I can drive the truck if I baby it and even get it up to freeway speeds 70mph. However, if I try to give it any real power it will fall on its face every time at those above specs. The truck will shudder, shake and cut engine power until I let off of it. Very simmilar when the ABS / traction control will shut it down if the tires get loose.

Now, I've been working with the guys at PPEI and Wehrli to figure this out.They been doing me good trying to help figure this out. I have sent off a data log to Kory and waiting to hear back on that. So, while I wait I figure I would get some input from you guys. If anyone has had or heard of a problem like this I would appreciate your input. I'm trying to give my mechanic any help I can before he has to tear my truck back down again.

Also, my apologies if this isn't in the right discussion group.
 
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#4 ·
Thanks for the reply I'm currently working with motor ops on this . Cameron said the same thing just hard to find a road for data logs. With speed involved.
 
#5 ·
What ended up being the resolution to this issue?

We recently completed a CP3 conversion on a 2014 truck that was still running perfectly fine with the CP4. Now it does exactly what you described yours doing. Cranks and idles perfect, runs fine under very light load but anytime any load is applied/power demanded it will sputter, shake, and even cut off in some cases.

Fuel supply to the CP3 has been verified it holds a solid 10psi, watching data logs and the desired rail matches actual rail. I have checked over every plug and connection over and over. I have been back and forth with MotorOps, sent data logs, and videos but there seems to be no resolution
 
#6 ·
I wound up getting good data logs to cam at motorops. It was tough for me to get them because I would run out of road . It turned out to be a regulator adjustment. Like scott@sdp said. It's been good for like 15k miles so far.
 
#7 ·
My desired and actual rail pressure did match when it was starving but I noticed they would both drop to 26-27 k then it would nose over at that moment and stop pulling. Now both stay at 29k. So it was commanding it through regulator voltage I believe.
 
#8 ·
Did everyone get their stuff figured out??? I see this thread is a month old. I'm having what sounds like to be the exact same problem. Started out sputtering/hesitating at high rpm while trying to accel quickly...3/4 throttle to wot. Had my mechanic run datalogs and send them into motorops. Still waiting to hear back from that. But now it's doing the bogging down thing, falling on it's face when trying to accelerate at a decent rate. Fleece 10mm cp3 conversion and Fass Titanium 165. Truck ran great right after the delete (about a month ago), slowly got to this point.

Sent from my Moto Z (2) using Tapatalk
 
#11 ·
same here, below 50% throttle truck pulls hard anything over that and injection A goes to 3.0
 
#13 ·
ANSWER FOR ALL YOUR QUESTIONS. I spoke with danville. They said this is a recurring issue on the LML platform with a cp3, and it cant be tuned to remedy this. They actually recommended i go to a cp4 stroker pump with the upgraded regulator that protects the motor. I also have a 2013 3500srw denali hd with this issue and i have the 10mm stroker cp3. I thought it was my sump. I was wrong. Im so frustrated, now i feel like i have to to buy another damn injection pump.

Sent from my SM-G955U using Tapatalk
 
#14 ·
And for the record, shame on lincoln diesel in wi. They could have been honest and told me, but instead just made the sale and played dumb. I found this portion out through a friend that goes there too, they told him because he was talking to them about my truck. American capitalism at its greatest.

Sent from my SM-G955U using Tapatalk
 
#17 ·
I figured out my problem, I had the feed and the return backwards.
 
#19 ·
My 2011 Sierra Denali LML's Cp4 recently grenaded and took my whole fuel system with it. Had all new injectors, filters and cp3 installed. The lines and tank flushed. Cp3 is an exergy sportsman by wehrli.

The truck is tuned with EFI Live by Kory Willis. I had all my tunes upgraded for the new conversion and pump by Kory. I had the guys at PPEI help me upload the new tunes to my auto cal.

So, after everything was installed and I flashed the new tunes all is not well. The truck seems to be defueling around 2000rpm. The rail pressure is around 21 Kpsi and injector rate timing is a bot +5. This happens at any speed. I can drive the truck if I baby it and even get it up to freeway speeds 70mph. However, if I try to give it any real power it will fall on its face every time at those above specs. The truck will shudder, shake and cut engine power until I let off of it. Very simmilar when the ABS / traction control will shut it down if the tires get loose.

Now, I've been working with the guys at PPEI and Wehrli to figure this out.They been doing me good trying to help figure this out. I have sent off a data log to Kory and waiting to hear back on that. So, while I wait I figure I would get some input from you guys. If anyone has had or heard of a problem like this I would appreciate your input. I'm trying to give my mechanic any help I can before he has to tear my truck back down again.

Also, my apologies if this isn't in the right discussion group.
 
#28 ·
Hi make sure that you have the fuel feed supply line hooked up to the right big fitting which is next to the fuel pressure regulator on the back of the CP3 pump and the return line is on the side top I've had this problem and let me tell you the truck will run this way very hard to start but will not get enough fuel supply 😜🤦🏻‍♂️🤦🏻‍♂️
 
#21 ·
How bad is defueling? If it is something slight or only felt at WOT or heavy load it is likely the tuning for the regulator. Mine was bad and felt like it was defueling at anything over half throttle. My issue ended up being the return line regulator being restricted. New injector return line assembly and truck was good as new.
 
#22 ·
How did you figure out it was becoming restricted?
 
#23 ·
Also, I thought that the ULTIMATE answer to the "worlds catastrophic scare" to the cp4 issue, was to replace with a CP3 Pump??? This is the 1st time I've herd about this situation with LML, as i am in the market to change out my injection pump, as well.....
 
#24 ·
I battled this issue for 3 years and it turned out to be the fuel rail pressure relief is too low. Exergy has a 31k rail pressure relief I put it in and solved my problems. After new tunes from kory and talking to numerous people about it. I’ve got a fleece power flow 750cp3 and an SDP compound turbo kit on my 16 Denali drw.
 
#25 ·
Hey could you pm me, by any chance? I had a few Q's, and would love your opinion
 
#29 ·
I changed the cp4 out on my truck to a fleece cp3k and even after tuning and tuning revisions the truck still feels the same half throttle to 3/4 throttle surges only time I can floor it without it surging is if I just gun it. Could the fuel regulator be the issue I have no starting or loping idle issues and no codes.
Font Line Slope Parallel Rectangle

The white line is the commanded fuel rail pressure and the purple line is the actual fuel rail pressure, the surging is visible through a time graph via the spiking above and below the white line and you can feel it and hear it too.
 
#31 ·
I purchased a 2013 chevy 3500, after doing some research I opted to do an injection pump by S&S that required no tuning. In addition, I had an Air Dog lift pump installed. Pulling away from my mechanic, I tried to accelerate but observed that truck loss power around 2000-2500 RPM. In park it will go to about 4000 RPM. Under a load it refuses to do what it should. Mechanic checked lines, tested the fuel went over everything he did. He suggested to tune, so EZ link purchased and tune done and still no luck. Any advice greatly appreciated or if anyone has experienced a similar issue I would like to hear from you, thanks in advance.


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Ron Nielson
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#2 · Aug 9, 2022

Your subject was high rail pressure yet nothing in your post suggests that. Why?

Ron Nielson - Most of the information I provide relates directly to my 2008 LMM - Your truck may be a little (or a lot) different
2008 Silverado LT, Crew Cab, 2WD,LB
..


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yglesiasemilio
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Discussion Starter · #3 · Aug 10, 2022

Ron Nielson said:
Your subject was high rail pressure yet nothing in your post suggests that. Why?
I posted high rail pressure because that's what the mechanic that did the injection pump said it was reading on the analyzer. To be quite frank when diesel mechanics start talking technical jargon, they might as well speak in Martian. I'm just trying to find out if anyone has had a similar issue and find out how it was remedied.


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MIkey52
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#4 · Aug 10, 2022

Never heard of high rail pressure limiting rpm's, but low rail pressure, yes.


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yglesiasemilio
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Discussion Starter · #5 · Aug 10, 2022

Ron Nielson said:
Your subject was high rail pressure yet nothing in your post suggests that. Why?
MIkey52 said:
Never heard of high rail pressure limiting rpm's, but low rail pressure, yes.
I hopefully will have my mechanic on this thread soon. At least he will be able to give a better technical explanation to what is happening, thanks for reply.


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Ron Nielson
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#6 · Aug 10, 2022

Attached is the info I have on P0088, high fuel rail pressure. Won't mean much to the OP, but at least it's one specific condition. Also see P0088 - Chevrolet Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis Your mech could possibly mean that the lift pump pressure is too high for your particular truck and setup. It could mean lots of things.


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Ron Nielson - Most of the information I provide relates directly to my 2008 LMM - Your truck may be a little (or a lot) different
2008 Silverado LT, Crew Cab, 2WD,LB
..


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Joseph-Lorefice
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#7 · Aug 12, 2022

Hi all I’m the tech that did the work on the vehicle. Prior to installing the cp3 conversion kit the truck was running and driving perfectly. At some point the vehicle had cp4 failure and by the looks of it. The lines injectors pump and rails were replaced. Not the best attention to detail but none the less it ran fine. Fast forward to the fun part. Take the truck on a test drive I never like to beat on them
Out of the box so I didn’t realize any driveability issues. Give the vehicle back makes it down the block the customer said he can’t get over 2,000 rpm. I didn’t believe it because I put five or so moles
On it no issue but again I wasn’t giving it the berries. Hook up my versus scan tool and start watching some
Live data. Frp actual and desired match through out the power and and fuel pressure is constant at 12 to the cp4 with the air dog. Checked all lines and fitting no leaks no air bounds. The truck will cut power at exactly 2250 rpm. Like the traction control comes on. Lose all pedal until you release and ease back into it. No
Metal particals were found in the regulator on the old cp4 pump might I add so fuel contamination is out. The only reason I’m going to a tuning issue is because the pump that was installed was supposedly an emissions compliant pump but yet there was no fuel feed port for the 9th injector so my thought is why can this pump be called no tuning when clearly the 9th injector would have to be removed and turned off to use this pump. Anyway speaking with a few people we got hooked up with great white northern diesel and ccs tuning. A couple
Of cp3 conversion tunes later nothing. Did the second regulator fuel fill test. Held 1500 rpm for 15 seconds had below the amount threshold for fuel bleed off so I’m ruling out a bad regulator. I’m convinced it’s in the tune just truing
To get the right person. I have seen numerous threads on here with people with the same issue just have not seen any resolve.

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yglesiasemilio
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Discussion Starter · #8 · Aug 12, 2022

Joseph-Lorefice said:
Hi all I’m the tech that did the work on the vehicle. Prior to installing the cp3 conversion kit the truck was running and driving perfectly. At some point the vehicle had cp4 failure and by the looks of it. The lines injectors pump and rails were replaced. Not the best attention to detail but none the less it ran fine. Fast forward to the fun part. Take the truck on a test drive I never like to beat on them
Out of the box so I didn’t realize any driveability issues. Give the vehicle back makes it down the block the customer said he can’t get over 2,000 rpm. I didn’t believe it because I put five or so moles
On it no issue but again I wasn’t giving it the berries. Hook up my versus scan tool and start watching some
Live data. Frp actual and desired match through out the power and and fuel pressure is constant at 12 to the cp4 with the air dog. Checked all lines and fitting no leaks no air bounds. The truck will cut power at exactly 2250 rpm. Like the traction control comes on. Lose all pedal until you release and ease back into it. No
Metal particals were found in the regulator on the old cp4 pump might I add so fuel contamination is out. The only reason I’m going to a tuning issue is because the pump that was installed was supposedly an emissions compliant pump but yet there was no fuel feed port for the 9th injector so my thought is why can this pump be called no tuning when clearly the 9th injector would have to be removed and turned off to use this pump. Anyway speaking with a few people we got hooked up with great white northern diesel and ccs tuning. A couple
Of cp3 conversion tunes later nothing. Did the second regulator fuel fill test. Held 1500 rpm for 15 seconds had below the amount threshold for fuel bleed off so I’m ruling out a bad regulator. I’m convinced it’s in the tune just truing
To get the right person. I have seen numerous threads on here with people with the same issue just have not seen any resolve.
Click to expand...
Thanks Joe, that was a mouthful! Hoping someone joins the thread with some insight or has run into a similar situation 🙏


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#34 ·
Sorry to resurrect this thread, but I'm having the exact same problem. Where did you get the part? I only found one vendor with an Exergy relief valve but there's no data on it. 15.5 Denali Crew Exergy Sportsman, Motor ops tune. I've since had it retuned and it's not as bad, but its obvious the spring is weak and causing pressure spikes. I'm waiting on Exergy to email me back.
Did you add an electric lift pump? It’s possible your CP3 isn’t keeping up with your tunes from the CP4. Supposedly it’s a much higher pressure between the 3 & 4. I’m not an expert but it seems as though you all are experiencing a fuel drop. My 13 seems to be a sunshine truck. If the wind n rain hit the drivers side it goes full retard.
 
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