is acting silly. At WOT I'm getting about 33 lbs of boost EGTs at 1100 and then the boost guage starts to "flutter" for lack of a better word. The guage will not hold steady it jumps about 4-5 lbs. It looks like a hummingbird wing its moving so fast. What is the most likely problem, besides operator error.

 

Bad gauge or a leak in the tubing/connections. Maybe fluid in the line? First thing I would do is check the connections and line. Then try a substitute gauge. Hopefully not a boost leak. Does the performance of the truck change with the gauge movements? Kevin

 

No change in performance, by SOP meter anyway. If I stay under 30 lbs of boost the guage is steady, little bit more pedal and it starts jumping.

I'll check the line and fittings next day off. Where would the fluid in the line come from?

 

Are you getting 33 lbs from a wastegated turbo? If so is it a 35? And are you using a boost elbow or a bleed valve? (or do you have a blocked WG?) I have seen bleed valve cause this because of their inherent trait of reaching full bleed potential at 30+ lbs and letting the WG see closer to actual boost. The gate cracks open and causes the flutter, then slams shut again....over and over this happens causing a bouncy needle. I have a bleed valve and orifice on mine and am switching to a spring/ball elbow.

Chris

 

Where is your gauge taped into? You shouldn't see spikes if you are close to the manifold unless you have intake valve blowby? If you are taped closer to the turbo, you may see the bleed valve/WG flutter? Not sure, but you probably have a loose fitting on your guage plumbing that leaks over 30 psi...

 

got...DIESEL? hit it on the head. If you are using a bleed valve it can cause the flutter when you're near the set point, your wastegate is probably fluttering also.

 

Whazzup:
Is your gauge a 35#?
Does it fluter thru out the range or only at WOT?
If you run at 33# you could have gotten a much higher spike?
My Autometer 35# did the fluter thing anything above 10# and it turned out to be the gauge was shot. In my case I think pinning it killed the gauge however the place I bought it from warenteed it and I upgraded to a 60# for $1 more

 

I have a 1/4" needle vlv instead of a boost elbow and from what was said that is probably the most likely culprit. At least that is what I got out of th info.

When I bought the guages I figured (wrong of course) that I would never have enough boost to need anything more than a 35 lb guage.

Thanks for the wisdom guys