Hello all; my girlfriend has owned her '05 CRD for five years now and it's mostly treated us really well. Closing in on 170k miles with few major issues in its time with us. Over the last five years I've put an OME lift on it and some bigger tires, kept up on oil changes, and generally just put miles on it. The previous owner did a sort of haphazard EMH mod with a provent. It's taken us all over, towed our sailboat, and gotten us up our insane driveway every winter. Oh and I had to change the little sensor that tells the dash which position the transfer case is in.

I should mention I put a turbo on it back in 2019 or so after the vanes seized in the original turbo and my attempts at oven-cleaner fixes (always worked on the junky TDI's I drove) failed. Okay so onto the problem:

The truck has almost always had the CEL come on every week or so for underboost; even after I put the new turbo on. Usually we'd never notice anything different but things have taken a turn recently. On uphill stretches, especially gentle ones, the truck looses boost and feels like it's in limp mode. When you crest the hill you will feel the boost come on with lag and then the truck is back to normal. No matter what is going on if you come off the throttle the turbo will make loud flutter noises like it's a JDM drift car. I'm assuming the vanes are sticking again and my questions are as follows:

1. What did we do wrong here? I know this is a common problem but I figured the EMH, provent, and new turbo would have gotten us more than 4 years of life?
2. How should I proceed? Give the truck its third turbo?
3. Maybe unrelated but injector 4's seal has failed and has the telltale loud tick and oily buildup to show for it. Could this be related?

I appreciate the insight and expertise. I have way less time at this point in my life to repair broken cars and no longer have access to a lift (not to mention which the truck's too tall to fit in our garage!)

A few things to consider and check!
Does it still have EGR system in service? If so, it is very hard on engine parts including turbo. All that soot going through the intake, combustion chamber and turbo, mixing with oil vapors makes one heck of a mess and gums everything up. Makes soot pies in the intake.
If you still have an EGR valve, it can stick open and you will lose boost pressure backwards through it allowing boost pressure to bypass engine and dump into the exhaust.
If you still have a FCV in service, they are notorious for the mechanical gears in the operator wearing out and sticking the valve partly shut or almost fully shut preventing air flow and boost pressure from entering the intake manifold. When this happens, it will severally engine and turbo performance making it act like it is in limp mode or it has a governor on the engine.

Check all your vacuum lines and hoses very carefully going to the turbo controls, vacuum solenoid, and vacuum modulator valve, and especially the one from the vacuum modulator over to the turbo actuator. The factory vacuum lines can get holes in them or the plastic ones can get briddle and snap or get to hot and collapse preventing proper turbo vane control. (See second picture below of bad factory vacuum lines/hoses) Replacing all the factory vacuum lines and hoses with silicone ones is a good mod as the silicone ones are impervious to heat and oil and won't collapse.

You can also do a vacuum solenoid bypass test to make sure the turbo vacuum solenoid is not causing problems. See pictures below.
Improper boost will really make these engines run very poorly and produce excessive black smoke.
If you still have a CAT in the exhaust system, it can stop up and severally limit turbo and engine performance.
Also, check the inlet side of your turbo and make sure the rubber pipe between the air cleaner box and turbo inlet has not come apart and allowed a piece of rubber to get sucked into the turbo.

Having a mechanical boost gauge can tell you if you having boost issues.

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05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

Thanks for the tips; I'll check it out this weekend.

The EGR is unfortunately still in place. When we bought it I'd intended to get a GDE tune and delete that and then the whole EPA thing happened with diesel tunes and there went that idea. Years ago I took off the elbow and cleaned all the crud out (there was a decent amount). I was not aware of the FCV problems and that does sound reminiscent of my symptoms.

Boost hoses have all been upgraded to SAMCO by the previous owner. I have replaced some, but not all, of the turbo control hoses with silicone. The hard plastic one between control unit and actuator had broken. I'll try the bypass though and see if it makes a difference. I think I have a boost gauge somewhere in my Volvo parts stash that I could verify boost pressure with.

I'll report back once I've dug in a bit.

Only had time to bypass the vacuum solenoid and that provided no change in symptoms. Tomorrow I'll dig into the intake side and see what the situation is. I see that intake elbow kits for these trucks are still readily available so maybe it's time to just bypass all EGR stuff. We're in PA anyway, so no emissions requirements for diesels.

I had the same problem and spent a lot of time and money trying to find the it. It finally came down to the transmission cooler lines going into the cooler were spelit/cracked/deteriorated allowing air to be sucked in. The tranny computer saw this and for some reason this disables the turbo vacuum solenoid from engaging. I know that sounds odd but believe me that was the cause of my problem in my 2005 crd.

I chased every suggestion given on here to no avail until the hose started leaking. I bypassed the built in cooler with a hayden cooler I wire tied to front the electric fan and hose clamped the existing rubber lines to the nipples of the new cooler. Problem fixed.

I had a commander with a rough idle issue and had done all the normal attempts as fixing such as spark plugs to no avail. Finally I found a post somewhere that said if you have done all those then the 545RE will cause this if the filter neck seal is leaking air into the fluid. The computer will cause engine problems............... We have the same tranny.

Randy

Intriguing.... I'll have to take a look.

The timing belt is due around May/June so I think I'm going to block off 3-4 days and really tear into this thing. Timing belt, intake elbow kit, redo the ProVent lines (they're all oily), all vacuum lines over to silicone, and reseal injectors.

I'll certainly give the cooler lines a looking over.

Long time: no update, so let me fix that.

I did the timing belt service last month across roughly two days in total working at a leisurely pace. All in all, not too bad but wow did they absolutely bury this engine in there. Just getting to the timing belt took me ages! The only surprises that came up were how badly clogged with gunk and material the radiator, intercooler, and a/c condenser fins were. It looked like oil, dirt, and other road debris was blocking of a full third of each. I powerwashed those all clean.

I re-did much of the crankcase ventilation hoses which were getting pinched shut and leaking oil everywhere. I cleaned out the CCV which was completely oil soaked. It may need replacement.

Finally we took it to a local diesel mechanic to reseal injector #4 which had significant black carbon buildup around it.

After all of this, many of the symptoms I mentioned in my first post are gone, but I'm not sure why. The truck still doesn't feel completely right but it drives MUCH better. Basically it feels like the boost comes on slower than it should; sort of like driving an older, waste-gated turbodiesel. But no more limp mode (or whatever that was), no more clouds of smoke, etc... I wonder if the injector seal leak was so bad that it was reducing compression significantly on #4? Anyway there's more to do, of course. I ordered the return line assembly from IDparts because it started leaking as soon as we got it home from the mechanic.

Two months gone by and a final(?) update.

The rear u-joint was wasted so I replaced that, put a new set of tires on it and it honestly feels just like it did when we bought it back in 2017. Smooth on the road, no more boost craziness, just driving like it should.

If there's a lesson in all of this I think it would be something like, get injector seal leaks taken care of and make sure your CCV hose routing isn't pinched or clogged!

Thanks for the update! Too many just post to try and get their problem solved then they vanish or don't report back. Really helpful to hear results. Glad you got your problem(s) fixed!

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2005 Liberty CRD, with 135,XXX miles. Rockers, exhaust valves, Provent, EGR block & butterfly delete & V6 air box at 100K

1998 XJ 4.0L, stock with 130,XXX miles

First Jeep: 1962 Willys CJ-3B