Got my boost gauge installed

[dustinarden]

Got the gauge installed yesterday. Pulls about 20ish on vacuum at idle. I've seen boost go as high as 20 (or really f'n close to it).

I've noticed when going WOT trying to see where I peak the needle is very "jittery". When i'm doing a nice long pull it seems far more stable as it climbs.

Is this normal or indicative of something that needs to be looked into?

I might be able to get a video of it, but I doubt it. Nothing says safe like video'n with one hand and trying to steer and shift with another :/

[Vansquish]

If you're on the stock tune/turbo, you're not pulling 20psi of vacuum, and you should be around 15psi of boost at a max. It sounds like something isn't working properly.

[dustinarden]

idle doesnt seem to be off. At least no different than it used to be. Is it possible the line is kinked or is leaking somewhere? I got two pretty nasty kinks in the line when pulling it up through the vent, but I clipped the line before those kinks.
I've noticed the vacuum goes down lower than the 20's at times. I think its when the clutch is engaged but not idle.

The only visible mod that I have that would relate to pressure is a cold air intake (mazdapeed CAI - filter is in the fender well next to the driver tire).

The boost pressure goes up to the 20's or just before it but again thats only at WOT and the needle is very shaky ...

[ihasmazda]

i used to have the same gauge on another car. Are you using the supplied air line that came with the gauge?

[dustinarden]

yeah. tiny little nylon/hard plastic 1/8inch line if i'm not mistaken. Have that tightened into the plastic T it came with (brass compression nut to the T from the line, and the same nut on the back of the gauge).

[JakeMS3]

Check it against your AP to see what its reading from the OBD. My vacuum is always around -9 I think it may have dipped into the -10's but never close to -20. I also am in MS3 not sure if you are in MS6 or not.. and if there is even a difference in vacuum between the two.

[dustinarden]

I don't have an access port. I wish I did!

I'm in an 07 speed6.

[davychronic]

Originally Posted by JakeMS3 Check it against your AP to see what its reading from the OBD. My vacuum is always around -9 I think it may have dipped into the -10's but never close to -20. I also am in MS3 not sure if you are in MS6 or not.. and if there is even a difference in vacuum between the two.

That's on an AP that reads -psi

@dustinarden; that boost gauge reads inches of mercury in vacuum and mine reads -22inMg at idle with ac off on my autometer mech gauge.

[dustinarden]

^Thanks!

I noticed at idle with AC on it tends to stick pretty close to -20. When in gear but not on the throttle i've seen it go down to -25 for sure. Confirmed today on the way into work. Also shot this quick video of the sputter i'm talking about. Video quality kinda sucks .. kind hard to make out what the needle is doing - but hoping someone can say "normal or not" haha.

https://youtu.be/HM_1h8lLNfM

[Yatta]

I would test the gauge with a vacuum pump and/or a known good source of pressure... seems to be reading high on both ends? or maybe its ‘Absolute’ pressure (I kid).

[davychronic]

Mechanical boost gauges have that flutter in the needle because of how the ebcs works. Mine does the same thing, no worries. With my ac on mine sits around 19inmg, i wouldnt worry about it. Youll notice on your ap when you are in boost, it never stays at the same number. Just the nature of the beast, if you dont like the flutter than an electric boost gauge should clear that up.

Originally Posted by Yatta I would test the gauge with a vacuum pump and/or a known good source of pressure... seems to be reading high on both ends? or maybe its ‘Absolute’ pressure (I kid).

Haha

[dustinarden]

I dont really mind the sputter to be honest. I just wanted the gauge to see where I was heading as far as boost goes. With the other mods done to the car I wanted to be sure I was at or close to stock levels.

@davychronic - thanks for the help. I appreciate it. Now I can go worry with important things.

[davychronic]

Yea its not smooth like spring operated boost control so its flucuates a lot under boost while the ebcs trys to maintain whatever boost you tell it to.

but if you are hitting 20psi under boost on a stock map something is SERIOUSLY wrong @dustinarden;

[Yatta]

didn’t catch the in/mg... another way to reduce (not remove) the needle hop is to use a liquid filled gauge, but an electronic gauge would be cheaper and more effective I think.

[ihasmazda]

Originally Posted by dustinarden I dont really mind the sputter to be honest. I just wanted the gauge to see where I was heading as far as boost goes. With the other mods done to the car I wanted to be sure I was at or close to stock levels. @davychronic - thanks for the help. I appreciate it. Now I can go worry with important things.

which gauge pod do you have there. i need to pick one of those up before they disappear like every other ms6 part...

[dustinarden]

Originally Posted by davychronic Yea its not smooth like spring operated boost control so its flucuates a lot under boost while the ebcs trys to maintain whatever boost you tell it to. but if you are hitting 20psi under boost on a stock map something is SERIOUSLY wrong @dustinarden;

I was watching it today and it seemed to be more like 15-17 under WOT. I'm going to keep my eye on it for the next few days and see if I see it go to 20 again .. maybe I just thought it was 20?

Originally Posted by ihasmazda which gauge pod do you have there. i need to pick one of those up before they disappear like every other ms6 part...

its a blockhead8 pod molded into the stock vent. The transaction went very smooth with him. Paypal'd the money and had the pod within a week or so.

painless! The vent seems to be a little looser than I would like, but I havent really tried to wedge it in there too hard yet (in case i had to fix anything with the wiring) but even as it is it hasnt moved at all during normal driving/throttle, etc. Very pleased with it so far!

[qtrmile beast]

first you should be idling about 18-20 in/hg's. The fluttering it like previously mention an issue with your EBC or your tune.