3800 Unwanted boost....could this be the bypass valve?

[AutoDummy]

During highway cruising I've noticed that I get a single bar of boost on the DIC with very little throttle input. The Autometer boost gauge shows 6-10 In Hg of vacuum when this occurs. My scanner revealed that I am getting 0.1 PSI of boost at this point. Boost is normal under/over 6-10 In Hg. I did do the "boost bypass mod" awhile ago, but went back to the stock setting shortly after. It has been several months since I did that. I'm a little puzzled that the DIC and my scanner show the 0.1 psi of boost, but the AM gauge does not.

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[imported_Ron Vogel]

Trust the gauge, the DIC and Autotap pull it's reading from the MAP sensor. The MAP and your add on guage pull the mechanical signal from the same line. If anything, sounds like the MAP has a problem. To check it, pull the vac line from the map sensor and plug it and check out the reading again.

 

[AutoDummy]

With the engine at normal operating temp, the MAP reads 8.59 at idle. With the vacuum line off and both ends plugged, the MAP signal reads 27.54. If I had to put a time frame on when this problem began, I would have to say it was right after I installed headers and the EGR simulator. The sim does tap into the MAP....

 

[imported_Ron Vogel]

The sim may be doing that to keep the egr from opening. I'd contact ZZP to be sure.

 

[AutoDummy]

Will do.....thanks.