LML 500 tuned miles, low power

[diesel53]

I tuned my 2016 LML with 20k miles. 200hp tune from ppei, all emissions still intact, and its running okay but noticeable power loss the more I drive it.

Fuel filter is new, no lift pump, and no other mods aside from tune. Slowly declining performance. I am thinking CP4 issues already, no codes or anything though.

Where should I start to look?

I was going to add a CP3 (dual kit) but this is making me question that decision haha.

 

[SSchmi5519]

You still have a CTS or something you can watch rail pressure with?

 

[Ne-max]

Check soot percentages. Knowing kory he sent ya a delete tune

 

[SSchmi5519]

Check soot percentages. Knowing kory he sent ya a delete tune

Nothing a reciprocating saw cant fix! :spit:

 

[AZlml]

I'd be more concerned with my trans if it's stock on a 200hp tune.

 

[IOWA LLY]

It couldn’t possibly be the emission equipment causing the problem. Just watch the pink slippers videos. He says his truck runs great with everything still place.


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[diesel53]

So I checked with my ez lynk, soot level was at 13. So it’s definitely low fuel pressure. I watched actual and demanded and actual kept bouncing around under demanded.

It’s a delete tune, but ran great at first. I just think the cp4 is already going bye bye. Truck won’t break the tires loose, like it’s not tuned at all.

Not concerned with the trans, I understand I’m in borrowed time haha. But kory’s trans tune is

 

[diesel53]

What’s max psi on a cp4? It’s around 22-23k hit 29k for a split second and Not again.

 

[Toxic]

A 200hp tune with a cp4 without a lift pump doesn't work well. The cp4 can't pull fuel fast enough to keep up with demand, so it drains the rails. This is what it sounds like you are experiencing. I'm sure all the soot from the delete tune is plugging the dpf quick also and creating back pressure. Max psi on a cp4 is 29k. Lift pump will fix the rail drain problem.

 

[diesel53]

A 200hp tune with a cp4 without a lift pump doesn't work well. The cp4 can't pull fuel fast enough to keep up with demand, so it drains the rails. This is what it sounds like you are experiencing. I'm sure all the soot from the delete tune is plugging the dpf quick also and creating back pressure. Max psi on a cp4 is 29k. Lift pump will fix the rail drain problem.

Ya but now the thing won’t even ramp up to 29k. It’s immediately dead feeling, like the pump is suddenly weakened. It ran well before and would lose power if you stayed in it, which I attributed to rail draining.

I may just have the pump tested. While I can before I delete it.

 

[PureHybrid]

There are some brand new cp4's for sale, incase you don't want to convert it.

 

[02greysixer]

Am I understanding correctly that you are trying to run a delete tune with the DPF still in place and power is slowly going down? If so the DPF is plugged I guarantee it. Pull that out and it will run fine. With a delete tune flashed in you can't trust what any emissions sensors say. The 13 grams of soot is probably where it was at when you flashed the tune in. I'll bet money your DPF is face plugged and she's breathing through a few little holes the size of a coffee stirrer. They do weird things With a plugged exhaust.

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[Columbus450]

X2 not sure why you would put a 200 hp and leave all the restriction in place, i'm almost willing to bet your diesel oxidation catalyst is plugged or dpf is plugged , with that being said your truck won't run worth a crap especially with said horsepower gains , please let your exhaust breath your engine will be much happier


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[oscyjack]

If it's only rail, try a lift pump. If still shitty it'll be time for a new decision lol

 

[duramaxzak]

So you are running a 200hp delete tune with the DPF still installed?

 

[diesel53]

I just would not think I’m under a 1000 miles tuned a dpf could plug up. Sawzall will make slight work of it if that’s the issue. I just didn’t like the rail pressure actuals I was seeing but if the exhaust was that restrictive I’m sure that would make the truck run worse.

 

[oscyjack]

Wait what... You got delete tunes? I thought you said you got emission in tact tunes...if not there is your answer

 

[IdahoRob]

Try this easy test, unbolt the dpf pipe from the cat pipe and wire it back.

I think that the dpf is plugged, as stated, a delete tune will show 13 soot grams no matter what.

Second issue, also stated, is that is way too big of a tune to run without a lift pump.

The cp4 isn't too bad but without a lift pump, it cannot do well on a big fuel tune.

 

[IOWA LLY]

Wait until you delete it. See how dirty that 200 Horsepower tune is....... You won’t be surprised at all at that point that your DPF is plugged.....


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[diesel53]

Thanks guys, I’ve ran the same tunes on my other deleted lml and it never ran really dirty butttt that doesn’t mean dpf isn’t loaded. I didn’t realize the soot levels remained the same on a delete tune. That’s probably my issue.

Step 1 delete
Step 2 more fuel
Step 3 trans/turbo haha