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| Turbo Under/Over Boost http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=75274 |
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| Author: | Beardo76 [ Thu May 16, 2013 2:44 pm ] |
| Post subject: | Turbo Under/Over Boost |
Hello all, new to the forum. I've got a 2006 Jeep Liberty CRD, 112k miles on it. I've got a CEL that comes on. Code reads as turbo under boost or over boost. The local stealership replaced a failed glow plug, then the EGR. CEL still comes on, and how they want to just replace the turbo. I've managed to find a diesel tech here where I live other than the stealership, and he cautions against replacing the turbo. In his opinion, turbos should last a heck of a lot longer than 112k miles. In any event, drive-ability doesn't seem to be affected. No loss of power (there was loss of power before EGR replacement). Thoughts on what could be causing the turbo over/under boost? |
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| Author: | papaindigo [ Thu May 16, 2013 3:23 pm ] |
| Post subject: | Re: Turbo Under/Over Boost |
Welcome aboard. IMPORTANT first question - do you have proof positive that the timing belt job has been done (not someone's "word" that it's been done but an actual work order or receipts). If not IMMEDIATELY park the vehicle and post your location (someone may be nearby that can assist) because the TB job needs done like right now if not sooner. As to your issue try the following as a starting point: 1. physically remove both CAC hoses (turbo>intercooler and intercooler>engine actually the flow control valve and carefully inspect for tears/cracks/oil soaking. If any of those 3 are found and you don't have Samco hoses replace with same. Check intercooler of leaks - look for oil drips especially where the core meets the plastic sides. 2. while in there for #1 remove air filter box to turbo hose and a) check for tear on bottom just in front of turbo and if torn get OEM replacement for ca. $65 (be sure on reinstall to push/pull the air box end up to where it touches the MAF sensor before tightening clamp). 3. while in there for #2 check visible turbo fan for play - slight for/aft is ok any side to side more that barely perceptible is not ok. 4. after it's all back together check turbo variable van actuator rod function. Per GDE "You can check the vane functionality at idle in park. Underneath the vacuum actuator on the turbo is rod extending downward connected to the vane mechanism. If you pull off the vacuum line at the turbo, the arm should drop about 1/2 inch and then raise back up after reconnecting the vacuum line. It is a bit difficult to see the rod, but this is the easiest method to check for proper VGT vane moevment." If there is insufficient movement get the vehicle up to operating temperature and try 2-3 hard full throttle accelerations up a modest rising road like the equivalent of an interstate on ramp (e.g. an Italian tuneup). Recheck; if still insufficient movement report back here. 5. try boost pressure solenoid bypass (viewtopic.php?f=5&t=70602&p=757348&hilit=boost+solenoid#p757348) if problem goes away and stays away replace solenoid. 6. unplug MAF sensor, will temporarily throw a CEL, and drive for a while; replug and do 3-5 drive cycles to clear MAF CEL if it clears there is an EGR problem. Don't throw money at EGR; throw same or less $s at GDE tune. Read Sir Sam's NOOB guide and try your best to avoid stealer that's just throwing parts at a problem they don't have a clue how to fix. |
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| Author: | Beardo76 [ Thu May 16, 2013 5:41 pm ] |
| Post subject: | Re: Turbo Under/Over Boost |
Thanks for the reply and the tips. I'll check on those ASAP. TB has not been done. Is being done next Tuesday. |
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| Author: | Glend [ Thu May 16, 2013 6:32 pm ] |
| Post subject: | Re: Turbo Under/Over Boost |
I was speaking to a local Jeep mechanic who drives and repairs CRDs and he tells me that often this is fixed by replacing the turbo controller solenoid. |
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| Author: | papaindigo [ Fri May 17, 2013 6:48 am ] |
| Post subject: | Re: Turbo Under/Over Boost |
Turbo controller solenoid = boost pressure solenoid |
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