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Boost fluctuation 5-10psi at 65mph?

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Old Feb 21, 2015 | 08:06 AM
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Boost fluctuation 5-10psi at 65mph?
While on the freeway using cruise control at 70mph my boost guage readings fluctuate between 5-10 pounds.Dont notice and issue with Rpms and drop in power just a difference in boost.Doesnt seem normal considering im at a constant speed.Suggestions? thanks guys
 
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Old Feb 21, 2015 | 08:39 AM
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What type of gauge is it and where is the fitting plugged into to read the pressure?
 
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Old Feb 21, 2015 | 08:41 AM
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Also , do you have a scanner or something like auto Enginuity to compare the MAP reading to the gauge reading?
 
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Old Feb 21, 2015 | 10:10 AM
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Wind, hills... stuff like that. What are your RPMs?
 
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Old Feb 21, 2015 | 10:28 AM
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Boost is an indication of engine load and not speed. Have you notice when parked (no load), regardless of RPM, you can't get boost? When cruising down the freeway, changes in wind, and grade will cause changes in boost. Boost will rise on even the slightest uphill grade and drop in the slightest down grade.
 
Last edited by HD Rider; Feb 21, 2015 at 10:28 AM. Reason: add
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Old Feb 21, 2015 | 11:15 AM
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Also, cruise control is pretty **** about keeping speed exact. Is bet your boost is moving because the cruise says 64.9mph is too slow and 65.1 is too fast.
 
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Old Feb 21, 2015 | 01:54 PM
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Is it a gradual needle movement or an erratic bouncing around type movement?

5-10 psi is a kinda big fluctuation.
 
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Old Feb 22, 2015 | 10:59 PM
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no it's kinda slow...it will slowly good down and then slowly rise.Automete sport-comp II is the brand.
 
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Old Feb 22, 2015 | 11:24 PM
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What is the outside air temp?

It could be the EBPV closing slightly to help the engine maintain operating temp.
 
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Old Feb 22, 2015 | 11:29 PM
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ebpv was delted and Unplugged professionally.its winter in Michigan so anywhere from -25-30 now a days
 
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Old Feb 23, 2015 | 06:58 AM
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My bad - I initialy took it as a bouncy erratic gauge needle. Maybe a video clip would be beneficial.
 
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Old Feb 23, 2015 | 06:17 PM
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Is this truck new to you or is having a boost gauge new to you?

Just trying to get some context,it does not pay to leave any question unasked particularly on the Internet.
 
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Old Feb 23, 2015 | 09:13 PM
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Originally Posted by mfrank1296
While on the freeway using cruise control at 70mph my boost guage readings fluctuate between 5-10 pounds.Dont notice and issue with Rpms and drop in power just a difference in boost.Doesnt seem normal considering im at a constant speed.Suggestions? thanks guys
Boost Pressure Test
 Verify that MAP hose is not damaged, plugged or pinched
 Verify that intercooler hoses or intake are not leaking.
 Verify that the green Wastegate hose is not plugged.
 Monitor MGP (manifold gauge pressure) and RPM with the NGS Tester
 Road Test - select appropriate gear to obtain desired engine speed and full load on engine (best accomplished climbing hill or truck fully loaded).
 Spec: MGP 15 PSIG Min
 
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Old Feb 24, 2015 | 07:41 AM
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Originally Posted by whitetmw
... Spec: MGP 15 PSIG Min
I should clarify. MGP min 15 PSI at WOT.
 
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