I just noticed today that my boost needle oscillates whenever the boost is between 10 and 25psi. It is rock solid above and below those pressures. The movement amounts to something like plus and minus 1/2 psi (1psi total movement) and it is pretty fast... the tip of the needle is basically a blur.

Has anybody seen this before? Do I have a bad gauge? Bad hose? Or is it indicative of some other intake problem?

By the way this is an Auto Meter "Phantom" 2-1/16" 0-35PSI mechanical boost gauge. It is run into a "boost bolt" in the intake manifold.

Thanks
-Mark

 

YA mine does the same thing. I have the same gauge as you. I went through and checked connections found nothing.

 

I have the 60psi gauge and mine does the exact same thing. Checked mine also and found nothing wrong.

 

Same thing here too. I was told that because of the location of the boost bolt and that the pressure fluctuates because of the opening and closing of the valves of the closest cylinder.

 

Okay, thanks for the feedback so far. Funny thing is, I don't recall the needle bouncing before... and the gauge has been there for more than 2 years. Maybe my eyes are getting old

Anyway, I am going to move the boost tube to a port on my (Pusher) intake horn and see if there's any difference.

-Mark

 

I took out the boost bolt and moved the pressure tube to a port on my intake horn. Now the pressure reading is stable regardless of the boost pressure.

-Mark

 

I have a similar problem now and had it a couple years ago, I found a cracked boost line at the gauge; it would flutter at high boost. I havent looked into the current problem....yet.