Need a little info on boost control and fix's for spiking etc!

[turbovanman²]

Sorry guys, this isn't my strong point. Ok, my issue was the boost wasn't stable, I would punch it, mostly in the midrange and at low boost, say 15-20 psi, the boost would float, so it would go between 15-20 lbs, surging as you will. I added some preload and it was alot better. So with the head off, I noticed there wasn't much tension still on the wastegate so I added another washer. Now, it will go to 20 then settle at 13 ish and doen't surge so what are the fixes for this? I had to stretch the spring on my Dawes MBC to get more boost-is that part of it?

[David Bohrer]

Simon,

Check the MBC for leakage. I just went thru something very similiar. Boost would hit target of 24 psi and then bleed down to wastegate/spring setting. It turned out that the seat for the check ball INSIDE the MBC had gotten damaged somehow and was allowing the boost to bypass.

good luck!

Dave B.

[Turbulence]

Yeah it may be dirt in the grainger. I had the same problem, cleaned the grainger with alcohol and put a small lawnmower fuel filter in line before the grainger--problem solved (one of good ol' Gus's ideas).

Martin
89 Horizon

[turbovanman²]

Well an update, I cranked it in all the way and it would hit 25 then down to 15 so I borrowed a friends brand new one. Cranked it up, would hit 26 ish and settle to 21 ish. I put a copper ferule in it and its aprox 4 turns from being bottomed out, 28 psi and its pretty solid, :thumb:

[MiniMopar]

Yeah, I use a fuel filter for a honda carb or something. Keeps the junk out.