Boost/rpm flutter

[larrym]

So what would cause this? It is not as noticeable 1-2 and it feels fine not really noticeable while driving but sure it's slowing me down. This is in 3rd gear my external gate need a rebuild?

[Scoobum]

How are your head gaskets?

[larrym]

good I hope no knock oils clean new last summer

[larrym]

blue is boost the orange is user fuel trim 

[Steve Wood]

You give us no scale..how much variation is the flutter that you see?

[larrym]

Sorry 2 psi max and about 65 rpm on the spikes

[Scoobum]

I did a search on the other board. Patrick Rubio...who's forgotten more about turbos than I'll ever learn had a post recommending to check for exhaust leaks at the headers, crossover pipe...and the three bolt flange. Other culprits can be head gasket(s), vacuum leaks, turbo getting weak, wastegate issue or intake gasket leaking.

I always seem to take a beating cuz I use exhaust gaskets, turbo gasket and new studs and nuts on the crossover...an d take my time tightening them evenly.

[larrym]

These are old KB headers with Vband clamps on the crossover I will put the stethoscope on and give it a good once over see what I can find. I run gaskets too never have to much problem with them.

[larrym]

I'm going seal this up see if it helps......

[larrym]

Found another leak....
Down pipe to turbo at the bottom right at the waste gate port ordered a remflex gasket to see if that will seal it up the cooper RTV was a no go and I really don't want to get the down pipe and exhaust housing surfaced that means pulling the housing off the turbo.

[good2win22]

Found another leak....
Down pipe to turbo at the bottom right at the waste gate port ordered a remflex gasket to see if that will seal it up the cooper RTV was a no go and I really don't want to get the down pipe and exhaust housing surfaced that means pulling the housing off the turbo.

I thought it was pretty common to see a leak at that point on the down pipe and turbine exhaust housing.  You could wrap some sand paper over a file and then run the file over the turbine housing to get an idea of how bad the surface is.  I don't think folks worry too much about post turbo exhaust leaks anyways.

[larrym]

With the external gate after the leak I'm thinking this could be cause of my boost fluctuation which seems to affect RPM in 3rd .
On the street it pulls great and with digital boost gauge I can see it fluctuate from 23 to 24 PSI.
The turbine protrudes outside the exhaust housing, its an F1 65mm turbine plus I would have to pull the studs I use to attach the down pipe to hand lap the housing.



My thoughts were if I could get the boost pressure at a soild number I would be better off running it out in 3rd at the track maybe pick up a half a tenth   

[larrym]

Well the 2 exhaust leaks are fixed with no real difference except an increase in max boost went from 23/24 to 24/25
There are no obvious vacuum leaks. My buddy suggested a new set of plugs and inspect the wires. If that has no affect I have 2 extra coils I will swap out and see if one of the six I have is the culprit.

[larrym]

Just so I'm correct in my thinking if I disconnect both vacuum lines To the gate I should be running on spring pressure in the gate alone say 15 psi?
If it climbs to 28 psi in the blink of an eye I have a problem......

[larrym]

next question  whats the best approach for hooking up a manual boost controller?
mine is set up as per figure 3.