With the engine running at idle, the vacuum to the turbo actuator should be high and the actuator lever at the full up position.
Then disconnect the vacuum line to the turbo and watch the lever drop.
Re connect the vacuum line and watch it pull up again.

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U.S. Army Retired

Make sure the turbo is fully assembled when checking the vane travel using the post listed above.

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Providers of wholly developed aftermarket solutions for the KJ CRD.
(248) 977 - 9531

Thanks you two! I'll do that assessment when I return from being out of state.

Thanks for the details and the help.

*fist-bump*

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2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.

Well from all the tests and replacement parts thus far, I am at a loss as to why I am still getting the P0234 CEL when I accelerate and push the RPMs between 3200-3800 for 4-5 seconds.

I am gonna try to replace all the vacuum lines and hoses to see if there is a leak causing this CEL.

If that doesn't fix it, I'll be pulling out the Turbo, dismantling it, and cleaning it through and through.

Bring on the fun!

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2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.

The problem is over boost, correct?
High vacuum = high boost
Low vacuum = low boost
If there was a vacuum leak, there would be low vacuum to the turbo and therefore low boost.
So a vacuum leak is not the problem.

A over boost code occurs when boost goes high, says high, and doesnt come back down quick enough to satisfy the ECM.
The problem is either with the turbo, the boost control solenoid, or the MAP sensor.

I say, if the code only occures at 3200+ rpm, dont rev it over 3200 rpm.
There are ways of fooling the MAP sensor so that the ECM thinks boost is lower than it actually is, but I would recommend installing a boost gauge before trying that.

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U.S. Army Retired

"I'm not sure how to go about "applying full vacuum to the turbo actuator and then let off the pressure" and see the actuator move."

You can use something along the lines of a "Mighty-Vac" tool. They are used for bleeding brakes, testing vacuum operated components, etc.

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2016 Ram 2500 4x4, 6.7 Cummins, 68RFE, Crew Cab
1995 Dodge Ram 2500 4x4, 5.9 Cummins, 47RH, Reg Cab
2005 Liberty CRD,fixed the rockers and a couple more things,GDE Hot tune,Weeks Stage 1 and 2 EGR delete,Hot Diesel solutions Tstat assembly(wonderful heat!), ARP studs, OME 1.5" lift.....thanks Seth!

... still working on trying to figure out the source of this Overboost...

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2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.

Did you ever rectify this problem? I have a 2006 that I have just finished re assembling after an engine replacement due to a valve failure. I’m currently getting the P0234 fault along with a few others associated with the egr delete. The vehicle accelerates well at first start up but after I left off the accelerator pedal the fault sets and puts the vehicle in limp mode. Is this your experience? Turbo has good travel and the vacuum bypass doesn’t make a difference either. Any easy way to verify that the MAP sensor is functioning properly?

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2006 Jeep Liberty CRD (sold to Mountainman)
2014 Jeep Wrangler Unlimited Rubicon(daily driver) - 2.5" OME Lift, Poison Spyder Front Bumper, Warn 10K winch
1993 Jeep Cherokee (sold)
1991 Jeep Wrangler (sold)

Order one of the GM PN: 55206797 MAP sensor and swap it out. That will rule out the MAP sensor as the issue.
The GM PN is a Bosch part but the cost is only around $20 bucks. Plenty of them listed on line on Amazon and many others.
IDParts also has this part:> https://www.idparts.com/map-sensor-libe ... -2859.html

GM PN: 55206797
Bosch PN: 68031593AA

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Supporting Vendor and Moderator of LOST
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

Ok, I went ahead and ordered a sensor from idparts so we will see if it makes a difference.

_________________
2006 Jeep Liberty CRD (sold to Mountainman)
2014 Jeep Wrangler Unlimited Rubicon(daily driver) - 2.5" OME Lift, Poison Spyder Front Bumper, Warn 10K winch
1993 Jeep Cherokee (sold)
1991 Jeep Wrangler (sold)

Be sure and post the results.

_________________
Supporting Vendor and Moderator of LOST
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

New sensor came in and it didn't make a difference. I also double checked the solenoid bypass and it appears to be correct. The only thing I can think to do is to pull the turbo back off and try to open it up so I can clean the vanes. Based on what Flash describes I should be having an over vacuum condition which means the vanes are open too much. I guess their is possible soot buildup in the vanes preventing them from fulling closing.

_________________
2006 Jeep Liberty CRD (sold to Mountainman)
2014 Jeep Wrangler Unlimited Rubicon(daily driver) - 2.5" OME Lift, Poison Spyder Front Bumper, Warn 10K winch
1993 Jeep Cherokee (sold)
1991 Jeep Wrangler (sold)

That is what happened to mine. The vanes were stuck. I took it off, cleaned the turbo vanes with Oven cleaner, cleared out the sludge and vacuumed out everything else with a heavy duty shopvac. I made sure the vanes moved easily, and put it back on, and then it was good as new.

I'm actually going to be upgrading my turbo with the Joe Kirian turbo in a few weeks here.

I'm excited to see how that one performs.

_________________
2005 Jeep Liberty CRD Limited: GDE Eco Tune, Weeks Kit 1&2, Provent 200, P3 E-Brake Controller, Custom Rock Rails, Suspension & Arms (OME, ARB, Raybestos, Bilsteins, etc.), 11-Bladed Fan, HD-Fan-Clutch, HDS M-001 Thermo, Fan-shroud-mod, Sasquatch Turbo, Tires: BFG AT TA KO2 LT245/70R16 - load D, Carter In-Tank Lift Pump.