Fluttering Boost Gauge
 

I just installed a set of Autometer Factory Match Gauges and love them with one exception. The boost gauge is fluttering when I get on it hard at about 30 lbs. What causes this? We tried two different ports, one up front and then moved it to the back and still have the fluttering. Bad gauge?

Thanks guys. I'm new to all this.

Greg.

Your waste gate is opening and closing. It's normal.

I cured that problem by moving the boost gauge tap from a boost bolt in the manifold to the intake horn. Not sure it that is what you mean by "we tried two different ports..."

What I was trying to say was we had the boost bolt up front and then relocated to another port back towards the firewall.

I'll try a snubber and see if that works any better.

Greg.

Mine does the same thing when I get on it, it starts at about 15lbs of boost. I'm using the boost bolt in the manifold.

where do you get the snubber? I couldn't find it on Geno's.

The wastegate on your truck keeps the boost around 30. Since the WG solenoid is electronically actuated the operation isn't smooth. Boost will spike to about 32 psi, then the WG opens, and boost drops. WOT should keep boost about 28-30 without a load and 28-32 with a load, but what you are seeing is normal.


I have found that the intake horn gives high readings, about 2-3 psi high at WOT. This is due to the large restriction in horn. That restriction probably softens the WG effect, but its not the true boost the head is seeing.

I don't have a stock intake horn.

Interesting, I wonder what the difference is? I haven't measured boost at my horn since I swapped out the stock one, but I also don't get any unusual fluttering in the head vs the OE horn; just a lower, more accurate boost reading.

I also run a quad boost fooler and my gauge fluttered well before it reached the wastegate level when it was in the boost bolt.

My original gauge fluttered a little and then wouldn't go above 25, but the gauge was defective, other than that, I don't see why the head would be different than the intake horn.. possibly a kink in the line that was remove/fixed with the move?? Or just PFM :-)

It's closer to the valves.

When getting on it unloaded, she'll get up to 32-33 lbs and flutter hard. How much more boost will I pull when I load the Smarty? I'm waiting a few days until I get some good baseline numbers before loading it.

Greg.

You won't get any more boost unless you run a boost fooler. Like AH64 said, the WG is electronically controlled to open around 30psi, regardless.

Yes, but the pressure should still be fairly uniform. The MAP pressure doesn't change either, as seen on a scanner. Mine is in the bolt closest to the valves, and doesn't flutter one bit.

If you have a Jr it will automatically boost fool, giving you about 32-35 on SW1, and more on the other 2, but I don't have good numbers for them.

If you have a Sr, you need to turn the WG off, and the boost will depend on the tuning.

My personal preference is to keep the boost below 38.

I have autometer gauges also (and love them-diehard:) ). I have twins turbos and my boost gauge will go nuts at times when jumpin' on it.....I read the posts and it makes sense that the wg is open/closing, even thou I have a vacuum wg. Since I've adjusted the wg to keep closed longer, I haven't had the gauge go nuts.

I'll be waiting to hear the explanation on that one. :rolleyes:

How do you have a vacuum WG? Never heard of that setup, so I am quite curious.

:rolleyes: all you want, boost is steady, valve operation doesn't effect the readings on the gauge. I have run 6 different boost gauges in 2 spots on my truck, mechanical and electronic, none fluctuate except at WG operation (especially on a 04.5-07 because of the command valve that applies ~30 psi to a 24psi WG, it slams open, then shut as soon as the command valve closes), but the boost is steady. Even DP is steady, and it has much more pulsing than intake. The only one I had fluctuate was defective.

The things you haven't heard of would obviously fill volumes. So I take it you won't be explaining this one? [laugh]

Explaining no, hence the ?.. Simple feature of the English language, it allows us to ask about something with which were unclear, you should try it sometime.

Did somebody pee in your Wheaties today? Or did you forget your medication...[dummy]

You're the one claiming to know all about this phenomenon, not me.

Not sure its phenomenon when its how it should be.

I have the same exact gauges. Had the same exact problem.

http://i557.photobucket.com/albums/s...h_IMG_0290.jpg

This cured it.

Ditch the banjo bolt and tap the manifold. Being a deleted 6.7 guy I only had to tap the EGR blocker plate.

Gauge is rock solid now...

Ace & AH64ID haven't you A-Holes ever worked on honey dues and don't use a computer for a day or 2??

You got me when I stated vacuum which should of been pressure...But the rest is what I experienced on my gauge, it doesn't flutter at all since I did and adjustment on the wg (mech.).

Its the gauge and how its working. Put a snubber in and see if that helps or replace it. The Isspro gauges don't have this problem in any of the areas unless the gauge is the problem.

Sorry just onery, I guess. I'm working night shift now too, so that the standard excuse for my disposition this week. [coffee]
I knew that's what you meant. :cool:

Sorry as well.. We got derailed.

No hard feelings Ace.

Wasn't trying to "get" you.. thought it may have been something new. Sounds like yours was opening before there was enough air to lite the bottom turbo. Simple fixes are great, aren't they!

The WG on the 04.5-07's is still mechanical, same WG as 03-04, it just doesn't see air all the time, so it can fluctuate pretty hard, otherwise should be smooth.