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Driving down the road with the cruise on at 110km the boost gauge fluctuates up and down between 10 psi and somewhere around 2psi. There is no change in rpm. I took the truck to the dealer as soon as I got it to town, they scanned it and tell me nothing is wrong no engine codes or lights. The truck still seems to have power which makes me think the gauge might have crapped out. Does anyone have any idea what is going on here? since the dealer dosent seem to be able to help.
 

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as you go up or down hills the boost will change and the rpms dont have too
Boost varies with the load put on the engine
 

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my 6.4 used to do this when it was in Regen mode?
 

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My 11 does this from time to time as well. Not always, but I've noticed it more often here the last few weeks.
 

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Was your cruise control on? I have heard it regulates speed with adjusting boost over throttle position. Boost will fluctuate with wind and slight grade changes. Mine will do this more doing regen or a stiff head wind.
 

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Was your cruise control on? I have heard it regulates speed with adjusting boost over throttle position. Boost will fluctuate with wind and slight grade changes. Mine will do this more doing regen or a stiff head wind.
like said above, the first question is, did you have the cruise on?

If so, this is the "turbo surge" many of people have noticed. It is common on the 6.4s and 6.7s

It was explained to me as the pcm trying to match torque to the speed, when the cruise control is on. (therefore increasing and decreasing turbo boost) My 6.7 did this every once in awhile and drove me crazy. if you kick off the cruise control it should stop, drive a few miles and set the cruise again. this worked for mine.

Although i tuned with H&S at 8,000 miles and my truck hasnt had the turbo surge even once since then.:woot:
 
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