Chevy and GMC Duramax Diesel Forum banner

1 - 20 of 75 Posts

·
Registered
Joined
·
260 Posts
Discussion Starter #1
Background:

Bought a 2015 DenaliHD with 78k on it and was pretty happy with it until I started doing the research on the CP4 issue. I personally know someone who's CP4 blew up and saw enough posts on many different forums to get pretty uneasy about the risk. $$$$ I don't want to cough up in an emergency repair.
I live in a smog-required county so I would rather keep the emissions intact but considered registering it in a no-smog rural town and getting a new driver's license to be able to register it. Total pain in the arse.

Found a CP4.2 option from Exergy. Wehrli Custom Fab offers the following:

Link

Exergy 10MM CP4.2
internally has a heavy duty FPRV Screen to contain a pump failure
supports up to 800hp
Requires a tune
Lift pump required
No delete required
1 yr warranty
$2,200

Exergy Improved Stock CP4.2
internally has a heavy duty FPRV Screen to contain a pump failure
supports up to 600hp
Requires a tune
Lift pump not required but highly recommended
No delete required
1 yr warranty
$1050

Exergy System Saver Improved Stock Inlet Metering Valve with Screen MPROP
Screen to contain a CP4 failure
1 yr warranty
$240


Of these, I'm leaning toward the Improved Stock CP4. I'd like to do a moderate tune without a tranny upgrade and keep all the emissions intact.
Will be installing an Airdog II lift pump first.

Hope this helps others in this quandry.
 

·
Registered
Joined
·
84 Posts
I'd like to hear of an actual cp4 failure with this new heavy duty screen. They replaced the factory 60 micron screen with a dual layer 25 micron screen. Considering how sensitive the piezo injectors are, I'm skeptical to think that 25 microns is enough to save the rest of the fuel system... Hopefully I'm wrong though
 

·
Registered
Joined
·
21 Posts
Sorry for my lack of knowledge, but I assume the CP4 still needs to be removed to install the screen?
 

·
Registered
Joined
·
84 Posts
Sorry for my lack of knowledge, but I assume the CP4 still needs to be removed to install the screen?
No, just the FCA needs to be replaced which is on top of the cp4, behind the thermostat housing. Should be relatively easy to install
 

·
Premium Member
Joined
·
1,732 Posts
Has anyone installed this screen? I see it states for the CP4.2. Would this fit on our stock CP4? And directions?
 

·
Premium Member
Joined
·
460 Posts
Subscribe to this
 

·
Registered
Joined
·
260 Posts
Discussion Starter #9
Has anyone installed this screen? I see it states for the CP4.2. Would this fit on our stock CP4? And directions?
When I called Wehrli Custom they did not have instructions for the installation of the screen.


I was considering just the safety screen, but I'd like to keep emissions intact and do a moderate tune, which I don't think the stock CP4 can handle.

On the Improved Stock CP4.2 they didn't provide any details on what the improvements were other than more output and including the safety screen.
 

·
Registered
Joined
·
3,383 Posts

·
Registered
Joined
·
55 Posts
If that upgraded MPROP actually prevents high side contamination like it states then I'm buying one as soon as my warranty is up. Seems like a "must-have" upgrade for LML owners who need to remain emissions compliant.

Then there's this for the Powerstroke's CP4: https://www.accuratediesel.com/6-7l-powerstroke-disaster-prevention-kit.html

Wish we could get something like that for the LML!
 

·
Premium Member
Joined
·
1,732 Posts

·
Registered
Joined
·
158 Posts
I was under the assumption that the my truck a 15 LML had the upgraded CP4.2? What year was the upgraded cp4 brought in??
 

·
Premium Member
Joined
·
1,732 Posts
Good question, however I dunno. I dont concern myself with what Furd does. :neener
 

·
Premium Member
Joined
·
660 Posts
Maybe I can help out some.

1. The Exergy improved stock CP4.2 is a stock Bosch unit with their improved MPROP with a 25 micron metal screen in it.

2. The Exergy MPROP can be installed on all LML CP 4.2’S.

3. All LML units are CP 4.2’s. The 2 stands for 2 pistons. There is a CP 4.1 that is a 1 piston pump installed in VW’s (possibly others).

4. There are people that believe 25 microns is not small enough to protect the system, but after talking with Exergy I believe the theory behind the 25 micron screen is that it will catch the metal particles faster and shut the truck off sooner and hopefully keep enough metal out of the system that the rest of the components are saved.

5. They were convincing enough that I will be installing an upgraded MPROP on my stock CP4 this weekend. Along with a few more parts😁.

6. My stock CP4 and an AirDog 165 are handling 500 h.p. in a tuned daily driver without a problem.

7. The Return by-pass that jamilbk linked for the powerstrokes is being worked on by a member on here for the LML’s. It will require a lift pump and hopefully we will start hearing more about it in the next few months. I personally think this will be the best fix for a bad design.

While the CP3 conversion is the ultimate fix, there are a lot of CP4’s that get a good clean supply of fuel and are running around without a problem. The problem is if a CP4 does break is the cost to fix everything. A lift pump and one or possibly both of these “fixes” will hopefully prevent that.
 

·
Registered
Joined
·
260 Posts
Discussion Starter #18
Great info CDMax16.

When you talked with Exergy, did they provide any details on the Improved Stock CP4.2? Wehrli rep said that will support up to 600 hp with greater output and the Safety screen. No further details beyond that.

Wonder what internals were changed for the Improved Stock and measured increase in output. I was hoping to get a better built CP4.2 (whatever that means) with the Safety screen to handle a moderate tune and mitigate failure.
Understand it's still a CP4 with a questionable design but I figure if I'm reaching the CP4, at that point, may as well drop in an improvement.

Really don't want to do a CP3 swap and all that goes with it.
 

·
Premium Member
Joined
·
1,732 Posts
Maybe I can help out some.

1. The Exergy improved stock CP4.2 is a stock Bosch unit with their improved MPROP with a 25 micron metal screen in it.

2. The Exergy MPROP can be installed on all LML CP 4.2’S.

3. All LML units are CP 4.2’s. The 2 stands for 2 pistons. There is a CP 4.1 that is a 1 piston pump installed in VW’s (possibly others).

4. There are people that believe 25 microns is not small enough to protect the system, but after talking with Exergy I believe the theory behind the 25 micron screen is that it will catch the metal particles faster and shut the truck off sooner and hopefully keep enough metal out of the system that the rest of the components are saved.

5. They were convincing enough that I will be installing an upgraded MPROP on my stock CP4 this weekend. Along with a few more parts😁.

6. My stock CP4 and an AirDog 165 are handling 500 h.p. in a tuned daily driver without a problem.

7. The Return by-pass that jamilbk linked for the powerstrokes is being worked on by a member on here for the LML’s. It will require a lift pump and hopefully we will start hearing more about it in the next few months. I personally think this will be the best fix for a bad design.

While the CP3 conversion is the ultimate fix, there are a lot of CP4’s that get a good clean supply of fuel and are running around without a problem. The problem is if a CP4 does break is the cost to fix everything. A lift pump and one or possibly both of these “fixes” will hopefully prevent that.
I am very interested in this upgrade. I am at 140k miles with a CP4 and have no issues that I can tell. I am very picky with my fuel and filter it 3 times. I would grab this screen in a quick sec. However, looking at the whole scheme of things, swapping to a cp3 really isn’t that bad of an investment.
 
1 - 20 of 75 Posts
Top