MAP reading at WOT on NA motor
Posted: Mon Nov 16, 2015 12:31 am
I've noticed here recently that my MAP readings at WOT seem to be in a constant state of fluctuation, especially when viewed under higher resolution. Now to begin, I am very aware of plenum pressure pulses created by both acoustic sound waves as well as the disruption of air flow caused by the opening/closing of the intake valve but I'm not certain if what I'm seeing is considered a normal signature or not.
I've taken a screenshot of a WOT pull made in 2nd gear (as 2nd gear seemed to create the most spikes) for everyone to see and hopefully give some feedback on. This really all began after monitoring the MAP reading to check for airflow restrictions in my intake tract. I'd like to add that I initially was seeing spikes as high as 2.1" of vacuum 200-400 rpm's before my rev cut of 7k rpm's. But after making some very significant changes to both my intake and exhaust systems, max vacuum under WOT reduced to maybe 1.5" as well as a reading of atmospheric pressure (or 0.0") at the beginning of the pull....of which I had never seen before. So that tells me that improvements were definitely made. However, I am still working to achieve even less restriction and am currently working to narrow down the restriction to its culprit(s). My concern is really the alternating pressures as seen in the screenshot. Don't ever remember seeing it before but then again, I've only ran forced induction prior to my NA setup so can't go off of history. Oh, and because of the higher plenum vacuum, the fuel tables are tracing on both columns 9 and 10 rather than just 10 as seen on the far left hand of the image.
Thought from anyone?
I've taken a screenshot of a WOT pull made in 2nd gear (as 2nd gear seemed to create the most spikes) for everyone to see and hopefully give some feedback on. This really all began after monitoring the MAP reading to check for airflow restrictions in my intake tract. I'd like to add that I initially was seeing spikes as high as 2.1" of vacuum 200-400 rpm's before my rev cut of 7k rpm's. But after making some very significant changes to both my intake and exhaust systems, max vacuum under WOT reduced to maybe 1.5" as well as a reading of atmospheric pressure (or 0.0") at the beginning of the pull....of which I had never seen before. So that tells me that improvements were definitely made. However, I am still working to achieve even less restriction and am currently working to narrow down the restriction to its culprit(s). My concern is really the alternating pressures as seen in the screenshot. Don't ever remember seeing it before but then again, I've only ran forced induction prior to my NA setup so can't go off of history. Oh, and because of the higher plenum vacuum, the fuel tables are tracing on both columns 9 and 10 rather than just 10 as seen on the far left hand of the image.
Thought from anyone?