Boost Gauge Question

[roosterdiesel]

This morning I noticed that my boost gauge was reading a tick above the needle it rests on when not running at IDLE. I thought it might be the gauge because it’s cold. Got back from taking my son to school and did some testing. Blip the throttle, it dropped to the needle and came back up to the same place. Slowly rev it, it drops then slowly produces boost. I can regulate it with the throttle, I made 5 psi and could prolly make more. IIRC I use to have to rev the crap out of it to make 5 psi when parked. The part that really bothers me is the slight boost and drop to 0 when the throttle is blipped. What would cause this, I'm really at a loss!

BTW, I’m tied into the MAP line I got from DI.

 

[whatabudro]

I think the gauge may be out of calibration, and slight throttle rev is actuallly a vaccum reading? Just a guess though. Bryan

 

[roosterdiesel]

I thought that too, but most of the time the needle does rest on the pin when sitting at a light. I've only noticed it off the pin maybe 6 or so times.

 

[roosterdiesel]

Well on the way to work and on the way back the needle was on the 0. Pulled in the drive and blipped the throttle and you can see it move down to the pin and back up a little. A few times it made a couple pounds of boost. Guess my gauge changes calibration when it wants.

 

[whatabudro]

Don't know? I'll start watchin mine real close and post back. Bryan

 

[powerboatr]

you probably already did this BUT.
pull teh gauge out of the holder and check teh nylon tubing or ferule nut. they do back off every now and then plus temp swings could cause an already loose fitting to be looser.
also check the connection at your map hose TEE.
my gale banks ferules did that on my 92 quite often.

 

[roosterdiesel]

Wouldn't a loose fitting(leak) cause it to read less than what's being produced? I have very slight boost at idle sometimes.


BTW, this morning it's acting the same as yesterday morning. I think it has to do with the temp of the gauge. Like a spring harder to compress when cold than it is when hot. We'll see what it does this afternoon.