Normal Boost Readings on Stock MS3

[projectr13b]

So, I was having a slight concern about the readings I'm getting on boost pressure from my Ultra Gauge. Plugged it in yesterday for the first time. Boost pressure seems kind of funky to me, but this is my first turbo car and I want to make sure everything is good. No rough idles or rough acceleration. I'm not noticing a drop in power, and I've read that boost is limited in first and second gear, which might explain why I'm feeling more pulling once I hit third.

Reading without boost is at -10.44 psi. It varies a little, but that's where it sits most consistently.

In boost (anything over 3500 RPMs really) I can see it start to climb, but it never really evens out. I've seen it spike up to 16 psi a few times, and saw that stock boost is 15.6 psi, so I figured that's fairly normal. Most of the time it will drop back down to negative pressure (-1 to -3), then spike back up some more. While under boost, my AFR stays consistent.

Just want to make sure the readings I'm getting are correct. I've considered that the Ultra Gauge may be inaccurate, or that it may be too slow to keep up with the engine's boost readings, but everything else seems to be reading ok, just boost seemed off to me.

I just bought the car a few weeks ago. It's an 09 with about 49000 miles on it. I'm also still under warranty and it was certified by Mazda when I bought it. No idea if the previous owner modded it really. I know they removed a Sub and Amp, but didn't see a report of any performance mods being removed.

I searched for a while, but wasn't coming up with much info, so hopefully someone can throw me some info. I'd appreciate it.

[Keko]

i dont know what to say to this thread..

its normal. im not even sure what you are concerned about

[projectr13b]

Originally Posted by Keko i dont know what to say to this thread.. its normal. im not even sure what you are concerned about

Just wanted to know if that was all normal. Wasn't finding a lot. Wanted to confirm what I did find is all. thanks.

[mrpostman831]

That negative boost you see is normal, its called vacuum, you don't go postive boost untiil you get on it, waste gate closes, makes turbo spin faster, pressure overcomes vacuum, and so on... but yes all normal for turbo car

[hnda etr]

One thing is not clear. Are you saying that while in boost ie: your foot is floored on the gas the whole time, your boost gauge oscillates back and forth from neg psi to pos psi? All without lifting off the gas pedal?

Or are you saying that as you lift up and then press down the gas pedal, the psi changes?

Former is not normal, latter is normal.