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.