Daily Commute Headache

Tuf-Mud · **Posted:** Mon Nov 02, 2015 2:47 pm

So I'm having a issue with I believe Limp Mode. I drive 40 miles one way to work and on certain spots The Rig will go in to limp mode/Loses it's power. It is a fairly consistent but does not happen everyday. It will happen within 50-100ft of each area and I can not grasp my head around why it does this. It may be a Bump but these places are fairly smooth compared to other parts of the road during my commute that are far more rough and this does not happen. I have a boost gauge and my boost is consistent even with this issue. After I lose power I can't gain to much speed as it is going up a small incline but i can still build boost and the trans will still shift. If I push on the throttle to go I will get a underboost code otherwise no code is thrown if i pull over fairly quickly. If I do take my rig on a gravel/forest road it will be thrown into this limp mode/loss of power to the point where it is undrivable for the most part.

I don't think this is a fuel issue as I have already replaced the quick disconnects and added a facuet pump/Prime is always rock hard.
Vacuum lines I have all checked and are in good shape
Turbo was rebuilt by oregon fuel injectors not long ago so it is good
GDE Tune has been done.
Tranny has been rebuilt within the last 30000 miles

I have replaced all the other possible suspects; new Samco Hoses, Elbow kit, good airbox elbow, map sensor, boost sensors, thermostat, I have checked the wiring as well behind the filter head and they are good, i've done all of this within the last the last 30000 miles.

With how consistent this is at certain spots in the road I'm thinking this could be a ECU error during the Engine Management cycling?? This does not happen in the morning coming to work only going home? ANy Thoughts on what may be the culprit would be great as I'm stumped on what this could be?

flash7210 · **Posted:** Mon Nov 02, 2015 3:30 pm

The only code you get is for underboost?
If thats the case I would think its related to the MAP sensor, turbo, or one of the vacuum solenoids that controls the turbo boost actuator.

At idle, vacuum to the turbo actuator should be high. Pull that vacuum line to confirm. Then watch the actuator lever on the turbo. When you pull off the vacuum the lever should drop. Attach the vacuum line again and the lever should pull up.

There are all kinds of intermittent wiring faults that can cause limp mode but they should all throw a code when it happens.

racertracer · **Posted:** Tue Nov 03, 2015 6:25 am

If the code number is p0299 under boost, then you may be experiencing the common stuck turbo vanes from CRD's being babied.

Or in other words, CRD's that are never driven hard - wide open throttle - to shake the soot off the turbo vanes.

Check the vacuum plunger on the turbo for free movement.

I good way to do that is to use a vacuum pump.

If the plunger moves up and down freely then the vanes are OK but if the up and down movement of the plunger is non existant, then it is a sign that your turbo vanes are stuck. Usually due to a encrusted build up of soot/carbon around the vanes.

I good way to get the vanes moving again is to drive your vehicle till it reaches operating temperature (real HOT) and then floor the pedal to the metal (WOT wide open throttle) while going up a steep hill.

Do this many times, the code will return, no problem. You will see code p0299 come back, just turn it off with your code reader and redo the WOT up the steep hill again and again till the code stops coming back on.

If you don't have a vacuum pump then use a needle nose pliers to grab the shaft located on the lower parts of the turbo and see if it moves up and down freely.

No matter what, doing a WOT in a vehicle that is being babied is always a good thing and normal maintenance on Diesels.

funnyman06 · **Joined:** Sun Jul 06, 2014 7:46 pm **Posts:** 180

I had a similar issue and it was my turbo acting up. I bought a new one and it cleared everything up. I would try moving the turbo vanes, they are probably sticking.

Mountainman · **Posted:** Mon Nov 09, 2015 12:22 pm

Or, maybe the actuator or whatever the adjustment nut is controlling on the Turbo isn't set quite right? Has it does this ever since the rebuild? I have heard the adjustments are tough to get right.

Tuf-Mud · **Posted:** Tue Nov 10, 2015 3:36 pm

I've pulled the vacuum line and the Actuator moves a good amount. I've also had a GDE Tune since the Rebuild as well so it shouldn't be from soot in the turbo and all the sensors have been recently replaced.

Now just to be clear It does not throw the code when it goes to limp. It will only throw the code after it is in limp and I have to really mash on the pedal so i can get off the road and out of the way of traffic. if I don't really push the rig to get off the road then no code is thrown. I would assume that the code is caused by the limp mode itself and me pushing the libby in limp mode.

Mountainman wrote:

Or, maybe the actuator or whatever the adjustment nut is controlling on the Turbo isn't set quite right? Has it does this ever since the rebuild? I have heard the adjustments are tough to get right.

Is this easy to adjust this on my own, I haven't heard of this before?

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