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P0234 OBD Code
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=89068		 Page 1 of 1
Author:  joelukex4 [ Tue Jul 31, 2018 9:51 am ]
Post subject:  P0234 OBD Code
I have received a check engine light and read a P0234 overboost code twice in the last couple of months or so. Each time I clear the code and the check engine light stays off . Is this something I should worry about and needs to be addressed. What would cause this overboost condition? Is the turbo actuator rod sticking or the vanes on the turbo?
Author:  APC9199 [ Tue Jul 31, 2018 12:09 pm ]
Post subject:  Re: P0234 OBD Code
There are really only a couple options. You touched on one of them. Vane actuation is the easiest thing to check first, especially if you have access to a vacuum pump. If not, just let the motor idle and remove the vacuum line connected to the turbo actuator and watch the rod rise and fall as you repeatedly do it. It should move roughly 1/2" and do it fairly quickly and smoothly. If it takes more than about a second, or moves with a jerky motion, something is stuck. Usually running the engine hard on the highway with a lot of wide-open-throttle will burn out any buildup in the turbo. If it doesn't then a frustrating afternoon of taking the front half of the turbo off is in order. ALSO...check to make sure the lock nut on the actuator rod is snug. I recently had an overboost problem that was caused by a loose nut which I couldn't easily see from the top of the motor.

Check the turbo shaft for play to make sure the turbo isn't shot.

Cleaning the MAP sensor would also be a good thing to do before digging into anything mechanically.

If the vane actuation seems good and the MAP is clean, next would be to bypass the turbo vacuum modulator to see if you can force the opposite code. If it does, the modulator is fine. If it doesn't, then it needs to be replaced.
viewtopic.php?f=5&t=70602&p=757348&hilit=boost+solenoid#p757348
Author:  joelukex4 [ Tue Jul 31, 2018 1:19 pm ]
Post subject:  Re: P0234 OBD Code
This CRD is mainly used on the highway (>90%). Turbo vacuum modulator was changed a few years back. MAP is new. Turbo shaft is good.

I will have to check the vacuum actuator. I should get a code if the modulator is bad. I did the previous time.
Author:  APC9199 [ Tue Jul 31, 2018 3:35 pm ]
Post subject:  Re: P0234 OBD Code
joelukex4 wrote:
This CRD is mainly used on the highway (>90%). Turbo vacuum modulator was changed a few years back. MAP is new. Turbo shaft is good.

I will have to check the vacuum actuator. I should get a code if the modulator is bad. I did the previous time.


But does it get run HARD often enough? Driving it on the highway doesn't mean much in terms of turbo cleanliness if you're "hyper-miling" with it and it never gets pushed to its limits. I realize most of us don't drive that way, but the point remains. Confirm actuator movement and make sure the lock nut is snug, then we'll work on what's next.
Author:  joelukex4 [ Thu Sep 20, 2018 12:44 pm ]
Post subject:  Re: P0234 OBD Code and additional P0672 & P0107
After 150K miles the issues are starting to appear. Along with the intermittent P0234 code I also have had a P0107 code for the MAP sensor. and a P0671 & P0672 code for Glow plugs.

Back to the beginning, I started using an ounce or 2 of antifreeze every few thousand miles. Recently it is about 4oz every couple of thousand miles. 6 months ago I changed the MAP sensor and the electronic issues started popping up. The P0234 code started intermittently appearing. I received a p0671 code and replaced the #1 glow plug which solved that issue. A few months ago I received a P0672 code and replaced the #2 glow plug. Subsequent to that two months later I received codes P0234, P0107 & P0672 again. I replaced the MAP sensor again and changed the #2 glow plug for the second time. Now I had the #2 glow plug fail recently for the third time. I will not replace it again until I find the problem with the electronics.

Back to the loss of antifreeze. I continue to use a couple of ounces every few thousand miles. I've done the cold pressure check and receive no build up of pressure in the system. The overflow never shows any boil over. The temperature holds fine just short of 12 o'clock. I had it pressure checked which held for 20 minutes of testing. No water came out of the #1 or #2 glow plug holes. The system is dyed and shows no leaks.


Any thoughts on why I keep popping glow plugs or where the antifreeze is going.
Author:  WWDiesel [ Thu Sep 20, 2018 3:27 pm ]
Post subject:  Re: P0234 OBD Code and additional P0672 & P0107
joelukex4 wrote:
After 150K miles the issues are starting to appear. Along with the intermittent P0234 code I also have had a P0107 code for the MAP sensor. and a P0671 & P0672 code for Glow plugs.
Back to the beginning, I started using an ounce or 2 of antifreeze every few thousand miles. Recently it is about 4oz every couple of thousand miles. 6 months ago I changed the MAP sensor and the electronic issues started popping up. The P0234 code started intermittently appearing. I received a p0671 code and replaced the #1 glow plug which solved that issue. A few months ago I received a P0672 code and replaced the #2 glow plug. Subsequent to that two months later I received codes P0234, P0107 & P0672 again. I replaced the MAP sensor again and changed the #2 glow plug for the second time. Now I had the #2 glow plug fail recently for the third time. I will not replace it again until I find the problem with the electronics.
Back to the loss of antifreeze. I continue to use a couple of ounces every few thousand miles. I've done the cold pressure check and receive no build up of pressure in the system. The overflow never shows any boil over. The temperature holds fine just short of 12 o'clock. I had it pressure checked which held for 20 minutes of testing. No water came out of the #1 or #2 glow plug holes. The system is dyed and shows no leaks.
Any thoughts on why I keep popping glow plugs or where the antifreeze is going.

Is your EGR system and the EGR cooler still in service?
If so, the cooler could be leaking internally and allowing coolant to enter the intake air stream. The GP's probably don't like coolant getting sprayed on them. :(
Author:  joelukex4 [ Thu Sep 20, 2018 6:18 pm ]
Post subject:  Re: P0234 OBD Code
That was a thought but I didn't know if the egr valve could leak directly into the egr system. I do have a gde tune.
Author:  WWDiesel [ Thu Sep 20, 2018 10:42 pm ]
Post subject:  Re: P0234 OBD Code
joelukex4 wrote:
That was a thought but I didn't know if the egr valve could leak directly into the egr system. I do have a gde tune.

If the EGR system is still intack, it can leak coolant from the EGR cooler and get sucked into the intake under certain conditions.
NO tune can fully disable the EGR system completely. Only the installation of an EGR "block off" plate or total removal of the entire EGR system when installing the Weeks Elbow Kit can you fully guarantee no EGR leakby of either boost or coolant if the EGR cooler has an internal leak. :banghead:
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