Wastegate problem?

[encasemyheart]

On my SR20DET 240sx it looks like I may be having a problem with the wastegate.

It's a t3/t04b internally gated.

I adjusted the linkage between the wastegate actuator and the gate itself and now when I drive, it will work fine, but then it will just go to vacuum regardless of throttle position. I can have full throttle and it will hit maybe 4psi of boost and then creep back to idle vacuum, not zero, but actual vacuum. -15in/hg or around there.

It didn't start until I lengthened the link rod with it's built in screw shaft.

I tested the boost pressure for leaks and it holds 10psi fine, I had a few small leaks, but I fixed them and now it pretty much holds a steady 10psi.

I tried adjusting the rod back, but it will keep doing the same thing. I give it more and more throttle and it just falls into deep vacuum. Then I let off for a second completely and hit it again and it will hit boost and then right back to vacuum. If I just give it partial throttle it will build boost and hold a little better than it is now, but shows the same symptoms.

Any ideas? I've tried adjusting the rod and checked to make sure that the hose going from the turbo to actuator is good, and it is. I have no boost controller either. I know this just has to be a small adjustment, because it was working fine earlier.

[sgpnismo]

did u adjust it so the flapper door is all the way open or closed?????

[Hijacker]

how old is the turbo? i've seen tired turbos do what you're describing

[encasemyheart]

It's used, but it can't have more than 20,000 miles on it total. Absolutely NO shaft wobble or play whatsoever. The wheel is perfect and still has the paint on the compressor wheel used for balancing or whatever.

I adjusted the wastegate rod to be shorter at first, to gain about a psi, but afterwards I hit exactly 10psi in 3rd, but in fourth I'd hit like 11-12psi, so I decided to turn it back, well, I guess I turned it too far and hit like 7psi. A few more turns in the opposite direction and the boost needle didn't stop, I had to let off the throttle to get it from passing 14psi.

Now, it does afforementioned symptoms after another adjustment and it won't seem to let up.

[Hijacker]

try putting the stock actuator back on if you have it. It's set up to run 7 psi.

[encasemyheart]

I don't have the stocker.

But I had a thought, could a wastegate, even being fully open 100% of the time, actually cause engine VACUUM? I mean, if you think about it, wouldn't that just cause the turbo to not spool at all and the engine stay at 0psi at full throttle?

[Movingviolation240]

Sounds like a dieing turbo to me

[encasemyheart]

Sounds like a dieing turbo to me

I dunno about that, the turbo has been recently rebuilt over the last 9,000 miles or so and has absolutely zero shaft wobble or play.