Map Sensor plumbing
 

Howdy, I'm concerned about my Map sensor readings under boost. Right now my sensor is feeding from the vacuum spout closest to the firewall, near the brake booster line. I've also added a tiny little filter in the line, it's a flat disc w/ some foam material in it. Should my map readings look like this photo? The map would jog as much as 10 kpa with each spike. As you can see, it's heavily affecting my dependant variables (pw, spark, AFR)

http://www.mustangmods.com/ims/u/2186/3873/145901.jpg

If not my plumbing, could my wastegate feed line be that unstable?

I had the same problem on my emanage ultimate and Greddy pressure sensor. I used a 4 port manifold from Mcmaster Carr as a boost chamber (like they do on FD RX7s). It also served as a nice source for my BOV and boost guage without having to use any t's. My MAP readings smoothed out significantly after doing that.

another simple method is to make a restrictor for the MAP line. I've used welding tips for MIG welders with good success.

you can test to see if this will help by simply clamping some vice-grips around the map line and doing a fresh log. just be careful not to clamp down too much and kill the signal entirely :)

i'm using a big old plastic motorcycle fuel filter on my map line. it helped a lot. a datalog of mine is in the dyno&timesheet forum.