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P0299 & P0234 codes come up

'06 F350 with 77K miles
Some towing last weekend, first the green wrench comes on the way out, then on the way home the check engine light stays on. Both codes come up in the memory of the scanner. Both self tests show all good. Wondering if there's a established check list to work my way down to find the problem?
After the green wrench came on the truck did not pull as hard as before. No rough running, no smoke, just seemed under powered. I did see the stock boost gauge go to 25/30 on one hill so I backed off a bit. Thanks for any help you can offer.
Werner

P0299 Engine Under boost condition
P0234 Engine Over boost condition
 
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blacksnapon

Moderator
Staff member
theres 2 separate pinpoint tests for those codes. Essentially, you need to check MAP sensor, MAF sensor, EBP sensor, VGT solenoid operation, BARO sensor correlation with MAP,EBP sensors, and egr valve. Good place to start is cleaning the turbo and looking at the unison ring.
 
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Subscribed.......I was towing a while back and the CEL came on, I checked and found the PO299 code, cleared it and continued on for another 150 miles towing and have been driving around without towing ever since and have not had the code pop up again.
 
Generally, the 299 is the vanes inside the turbo not moving sufficiently. Stuck or worn unison ring is suspect.
That's what I found out after looking up the code.....the turbo seems to be doing what it should though, it will range from 0 to up around 27-28 and I was to understand that to be about right for a stock engine tune and stock turbo. Also it was the one and only time it has done this (threw the CEL and code) Do you still think the unison ring dirty or damaged to be the culprit? Just asking so if not that what next?

....and thanks for the help.
 

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