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I am at 93k on my 2015 LML. I had planned to do a full delete after my warranty is gone but that seems to be a home garage and canada tuner arrangement now. So I think I am going to go the emissions compliant route. My truck is currently bone stock aside from some suspension/wheel changes.

My plan was to safeguard my fuel system with an exergy system saver and a lift pump (can’t decide which one). Then throw some duramax tuner tunes at it. And I am at least doing this in the mean time.

But being that my buddy just blew his 16 gmc’s cp4 I am thinking of going a little deeper. He was at 75k and baby drives that truck by the way...

Anyways, I’m considering going with an S&S CP3 conversion or an exergy 10mm cp4.

The CP3 kind of speaks for itself and this kit is 50 state carb compliant and doesn’t require tuning, which I think is nice for selling the truck in the future.

However the guy from duramaxtuner tells me the cp3 isn’t without its failures and I have to hack up the fuel system to do the conversion. He assures me the exergy cp4 has upgraded components beyond the system saver metering valve and is a direct drop in. I believe the exergy pump requires tuning to run though which is a negative for when sell the truck as not everyone wants it.

I have also seen guys having fuel line leaks after their cp3 conversions where they did the line install. I certainly don’t want that.

I’m having some trouble making a decision. What is everyone’s opinion?
 

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From my understanding its not the components that make the CP4 so bad its the design of the pump. The CP3 has been proven to be a more reliable pump than the CP4. I also am pretty sure that you can get a CP3 conversion kit with sportsman pump for cheaper than the CP4 10mm pump. If it were me I would put a CP3 in and go on with life.
 

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Comparing cp3 failings to cp4s, saying youre "hacking" up the fuel system, and that the new cp4s are internally better?
Yup sounds like duramax tuner alright lol. Swap the cp3. If you have leaks afterwards you did it wrong.
 

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Discussion Starter #4
These were my thoughts as well. I felt like that was a loaded push. A cp3 may fail but I certainly haven't heard of any failing catastrophically in the way a cp4 does. Is there currently a way to do a sportsman cp3 with the emissions on? The S&S is the only kit I've found that works with the emissions, especially without a tune. Maybe there is another route I just don't know about? It would be nice to do an upgraded pump vs a stock one.

Should I be wary of DT's tunes? I figured I would go with them because they've been on the emissions side of tuning for a long time. I just haven't seen much as far as reviews are concerned when it comes to emissions on tuning from ppei. I know they are looking to up their game now, but before I think it's safe to say they were heavily invested on the other side of the fence.
 

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If life's still boring with your DPF, CAT, & EGR removed I'd suggest the maxxx effort file. Guaranteed to put some lead in that pencil.
 

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I am at 93k on my 2015 LML. I had planned to do a full delete after my warranty is gone but that seems to be a home garage and canada tuner arrangement now. So I think I am going to go the emissions compliant route. My truck is currently bone stock aside from some suspension/wheel changes.

My plan was to safeguard my fuel system with an exergy system saver and a lift pump (can’t decide which one). Then throw some duramax tuner tunes at it. And I am at least doing this in the mean time.

But being that my buddy just blew his 16 gmc’s cp4 I am thinking of going a little deeper. He was at 75k and baby drives that truck by the way...

Anyways, I’m considering going with an S&S CP3 conversion or an exergy 10mm cp4.

The CP3 kind of speaks for itself and this kit is 50 state carb compliant and doesn’t require tuning, which I think is nice for selling the truck in the future.

However the guy from duramaxtuner tells me the cp3 isn’t without its failures and I have to hack up the fuel system to do the conversion. He assures me the exergy cp4 has upgraded components beyond the system saver metering valve and is a direct drop in. I believe the exergy pump requires tuning to run though which is a negative for when sell the truck as not everyone wants it.

I have also seen guys having fuel line leaks after their cp3 conversions where they did the line install. I certainly don’t want that.

I’m having some trouble making a decision. What is everyone’s opinion?

let me start with this. The CP4 issue is blown out of proportion. The total number of failures is very low, they are just concentrated at places like forums so the problem appears larger. Thats not to say its not a problem, it is, but its not the ticking time bomb everyone thinks it is based on this and other forums.

Now that we have that out of the way for context, the CP3 is a significantly superior pump in terms of longevity as well as failure mitigation. The internal design of the CP4 is the issue, so upgrading part quality will help, but ultimately, it doesn't matter how high quality the parts are if the design is deficient. This topics been beat to death on this forum so if you want to know more there are several very lengthy threads to explain the differences in the pumps. Basically the CP3, if it were to fail, wont send metal through the high pressure system, or at least is far less likely to. The CP4 is guaranteed to send metal through the fuel system when it fails.

For this reason i would run the CP3 if you were replacing the pump. Also, ive seen the kits online and its far from "hacking up the fuel system". As for the fuel system saver, there is no evidence one way or the other at this time to show if it makes a difference. Personally, im not convinced they will make a significant difference in the failure.
 

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The service techs. at my local GMC dealer don't agree.

well yes.... they want to sell you new parts so that would make sense.
 

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I realize this is an older thread but I just wanna say that I did the S&S Emissions compliant CP3 in my 2013 LML and have no complaints thus far, worked just fine emissions intact and still works just fine with the emissions components on vacation. I wouldn't hesitate on spending the money on it again. I also realize that there are some upgraded CP4 options but like others have said, its the internal design that really helps ruin your fuel system when it goes. From what I understand, if a CP3 dies, it is just dead and you have to swap it out but it shouldn't take the injectors and other components with it.
 

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Wrong. Totally wrong. It happens that my local GM dealer organization has a long history & reputation of of "trying to do the right thing" for its customers. Which explains why they get so much "repeat business" even tho costs are higher than some guy working out of his back-yard.

I will not bore you with example after example where they COULD have taken advantage of my ignorance, but elected to show me the most economical way out.

Yes - I "get it"....some of you have the misfortune to be in areas where the service writers are just salespeople ( who I wouldn't trust/allow to competently change the spark plugs on my lawn mower ! ).

In my case, it was the techs at my local dealership who (quietly and "off-the-record") recommended both certain "adjustments" to my pollution controls AND who suggested a CP3 conversion should be considered mandatory to anyone who is both "out of warranty" AND who use their trucks as trucks, especially in rural areas where help may be a long walk away in ugly weather.
Against my better judgment, im going to try to explain again how this CP4 problem can be both a common failure, and an uncommon failure at the same time. Kind of like special relativity, it all comes down to perspective.

You have 3 samples of people to take data from. You have 10,000 people in each sample.

the first 10,000 are regular joes and joets who dont use forums, dont modify there trucks, and just drive them for a few years and trade up. These people are very unlikely to see a failure in the CP4 pump as they are 1, unlikely to have the truck long term, and 2, are unlikely to abuse it. These people are your average consumer making up the majority of your ownership base.

The second 10,000 are people from this forum. Forums are a collection of knowledge and a place for people of like interests to collaborate. This is going to attract people seeking help with problems. These people are going to report a higher than average failure rate, since the fact that they have a fuel system problem is likely to drive them to the forum for answers which skews your poll results and makes them appear to have a higher failure rate compared to your first group of standard owners. Even this group though only reports a 12% failure rate over 100K miles.

Your last group is 10,000 diesel mechanics at chevy dealerships. These guys spend all day long doing nothing but fixing broken trucks, so they are even more unintentionally biased than the previous group since the odds of a truck without problems rolling into there bay is basically 0. This group is much more likely to see a failure rate higher than the 12% we see on this forum, since they spend all day every day fixing this and other problems.

From these three examples you can see how with the same actual real world failure rate, you can spin the results to your liking based on who you sample for data. The media does this every day, its not a new thing. On one hand, GM can say they have a low failure rate because the average owner is likely to never see a failure. A law firm looking to make a buck could take the second sample of data to make the problem look much worse then it is . and the dealership, while maybe not intentionally misleading you, would use the third data sample as it is the one that is "most valid" to there experience.

The fact though is that the first group is by large the majority in the real world, followed by the second, and with GM diesel techs making up the minority.
 

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Against my better judgment, im going to try to explain again how this CP4 problem can be both a common failure, and an uncommon failure at the same time. Kind of like special relativity, it all comes down to perspective.

You have 3 samples of people to take data from. You have 10,000 people in each sample.

the first 10,000 are regular joes and joets who dont use forums, dont modify there trucks, and just drive them for a few years and trade up. These people are very unlikely to see a failure in the CP4 pump as they are 1, unlikely to have the truck long term, and 2, are unlikely to abuse it. These people are your average consumer making up the majority of your ownership base.

The second 10,000 are people from this forum. Forums are a collection of knowledge and a place for people of like interests to collaborate. This is going to attract people seeking help with problems. These people are going to report a higher than average failure rate, since the fact that they have a fuel system problem is likely to drive them to the forum for answers which skews your poll results and makes them appear to have a higher failure rate compared to your first group of standard owners. Even this group though only reports a 12% failure rate over 100K miles.

Your last group is 10,000 diesel mechanics at chevy dealerships. These guys spend all day long doing nothing but fixing broken trucks, so they are even more unintentionally biased than the previous group since the odds of a truck without problems rolling into there bay is basically 0. This group is much more likely to see a failure rate higher than the 12% we see on this forum, since they spend all day every day fixing this and other problems.

From these three examples you can see how with the same actual real world failure rate, you can spin the results to your liking based on who you sample for data. The media does this every day, its not a new thing. On one hand, GM can say they have a low failure rate because the average owner is likely to never see a failure. A law firm looking to make a buck could take the second sample of data to make the problem look much worse then it is . and the dealership, while maybe not intentionally misleading you, would use the third data sample as it is the one that is "most valid" to there experience.

The fact though is that the first group is by large the majority in the real world, followed by the second, and with GM diesel techs making up the minority.

You pretty much hit this one perfectly, no sensible way to argue with this.
 

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Against my better judgment, im going to try to explain again how this CP4 problem can be both a common failure, and an uncommon failure at the same time. Kind of like special relativity, it all comes down to perspective.



You have 3 samples of people to take data from. You have 10,000 people in each sample.



the first 10,000 are regular joes and joets who dont use forums, dont modify there trucks, and just drive them for a few years and trade up. These people are very unlikely to see a failure in the CP4 pump as they are 1, unlikely to have the truck long term, and 2, are unlikely to abuse it. These people are your average consumer making up the majority of your ownership base.



The second 10,000 are people from this forum. Forums are a collection of knowledge and a place for people of like interests to collaborate. This is going to attract people seeking help with problems. These people are going to report a higher than average failure rate, since the fact that they have a fuel system problem is likely to drive them to the forum for answers which skews your poll results and makes them appear to have a higher failure rate compared to your first group of standard owners. Even this group though only reports a 12% failure rate over 100K miles.



Your last group is 10,000 diesel mechanics at chevy dealerships. These guys spend all day long doing nothing but fixing broken trucks, so they are even more unintentionally biased than the previous group since the odds of a truck without problems rolling into there bay is basically 0. This group is much more likely to see a failure rate higher than the 12% we see on this forum, since they spend all day every day fixing this and other problems.



From these three examples you can see how with the same actual real world failure rate, you can spin the results to your liking based on who you sample for data. The media does this every day, its not a new thing. On one hand, GM can say they have a low failure rate because the average owner is likely to never see a failure. A law firm looking to make a buck could take the second sample of data to make the problem look much worse then it is . and the dealership, while maybe not intentionally misleading you, would use the third data sample as it is the one that is "most valid" to there experience.



The fact though is that the first group is by large the majority in the real world, followed by the second, and with GM diesel techs making up the minority.


Selection bias.
 
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