Nissan 370Z Forum - View Single Post - VVEL Question on Intake Manifold Pressure

SonicVQ · 01-08-2016, 07:34 PM

Thanks for the info. After some more searching I found this:

"The engine's speed and output is largely managed by ECU control of the intake valves, not the throttle bodies. By not having the restriction of the throttle blade at partial throttle, fuel wasting pumping loss is reduced.

The engine does have dual drive by wire throttle bodies but they are used only for brake booster vacuum control and quick acting modulation for traction control. Otherwise the throttles are wide open most of the time."

(source: ***************************************/tabid/57/articleType/ArticleView/articleId/14/PageID/62/Nissan-370Z-Review-Engine-VQ37VHR.aspx)
interesting, can't link to own site...
Try the370 dot com /MagazineArticles/tabid/57/articleType/ArticleView/articleId/14/PageID/62/Nissan-370Z-Review-Engine-VQ37VHR.aspx

I guess the MAP PID is being modified by the OBD-2 output to a "expected" value and not actual. If I am 20% throttle, constant speed, there should be none to little intake manifold vacuum - but the MAP PID shows ~15" vacuum.

01-08-2016, 07:34 PM	#4 (permalink)
SonicVQ Base Member Join Date: Jan 2016 Location: Ontario Posts: 230 Drives: G37 Sport Rep Power: 6720	Thanks for the info. After some more searching I found this: "The engine's speed and output is largely managed by ECU control of the intake valves, not the throttle bodies. By not having the restriction of the throttle blade at partial throttle, fuel wasting pumping loss is reduced. The engine does have dual drive by wire throttle bodies but they are used only for brake booster vacuum control and quick acting modulation for traction control. Otherwise the throttles are wide open most of the time." (source: ***************************************/tabid/57/articleType/ArticleView/articleId/14/PageID/62/Nissan-370Z-Review-Engine-VQ37VHR.aspx) interesting, can't link to own site... Try the370 dot com /MagazineArticles/tabid/57/articleType/ArticleView/articleId/14/PageID/62/Nissan-370Z-Review-Engine-VQ37VHR.aspx I guess the MAP PID is being modified by the OBD-2 output to a "expected" value and not actual. If I am 20% throttle, constant speed, there should be none to little intake manifold vacuum - but the MAP PID shows ~15" vacuum.