boost problems


Drive like you stole it!
May 25, 2001
I have problems keeping my boost stable. I have disconnected my bleeder valve and used only the wastegate. When I go full blast the boost will hit 17 and slowly go down to 14 then when it upshifts to 2nd it hits 17 again and goes back down again. Any ideas? I have turned the alky off but then I have to turn boost down to 11psi. It is stable then. I have not had a chance to run some high octane and see if it does the same thing.
Check for vac leaks..and if none come put then take off the Exhaust housing and check the Puck for sealing.
No vacuum leaks. I have checked. How do I make sure the puck is sealing? And if it is not sealing what do I do to fix it? I have rebuilt the turbo and I made the puck hole bigger but I did not have this problem untill I made changes to the intake and replaced the cam and alky injection this year. I did these when I rebuilt the motor this year. Before that it was fine.
I am having the same problem i set it at 12-13 psi and it hit 15 psi and then drops back , checked today no vac leaks and no ex leaks just open down pipe for now. I am running 110 cam 2 and no pump gas and it still does it . Not to good with the fuel press , could it be running to lean or rich and get to much gas or maybe to little in the higher rpm's. Let me know if you find the problem.

good luck
Checked the O2's today with turbolink. They ranged from 790 to 765 at WOT. It is a tad lean but I don't think enough to effect my boost.
Since it falls off at higher rpms, it sounds like the exhaust is plugged up. Cat, maybe?
Mine is doing the same and iam running open down pipe, has to be a leak some where , i know its driving me crazy to.

On the actuator there are 2 ports. If you have the one that connects to the vacuum block capped,(at the act.) remove the cap. When the pressure from the turbo is applied thru the hose to the act, the air that is trapped in the other side of act must be allowed to escape.
Capping of this port will make your boost act crazy. Let us know what the fix was.
1. There is no cat, just an atr test pipe and cat back system.
2. No knock retard. I have a knock gauge and a turbolink
3. I have an adjustabe wastegate from poston's with one port (pressure)
Lee and BFH could be on the right track... IMO, it could be the wastegate solenoid being told to open up by the chip, and the bleeder valve also doing it's own thing. Just use the bleeder valve and you should see an increase of about 1 psi per gear change.

Anyone been able to figure out a way to have manually adjusted boost AND be able to have more boost in 1st and slowly deacrease in 2nd and 3rd by 1 lb per gear? I'd like to do this... I just haven't ever trusted the chip to do it for me... call me nuts!
Today I put in some 110 octane and went tuning. I turned off the alky injection. Still boost is slacking off. Then I eleminated the phnematic regulator. Still boost is slacking off. Is it possiable that at the higher rpms when boost is falling off that the turbo can't keep up to the motors demands. The intake that I modified flows very well, and the eastern cam compliments it nicely. I did not have this problem before I made these modifactions.
Is it possible that the wastegate accuator is leaking? It is a new unit. I bought it 2 months ago. Is there a way to test the accuator?
Someone had suggested that the puck could be leaking. I don't understand how that would be possible. It will reach 17 psi at lower rpm's and drop off at the higher rpm's. If it didn't seal wouldn't you just see a overall drop in boost all through the rpm's?
Sounds like maybe the diaphragm in the actuator will not hold the amount of pressure you want to run. perhaps you need a new one.
If I remember correctly I replaced the accuator becuase I thought that my old one was the problem. It was orginal so it needed to be replaced.
So the accuator is new.
I had the same problem but it just want away when i changed to the 87 ecm and 93 pump gas. It did it with the 85 ecm and the 110 cam2 not to shore what this mines but maybe it will help some.

good luck
Just thought of a bad thing...valve float? (nah, fergit that!)

Have you changed wastegate solenoids? If yours, for whatever reason (dirt, faulty, etc) doesn't bleed off the excess pressure quick enough (or at all), your actuator will slowly open the puck!

About the turbo not being able to keep up with the engine's demands...turbo's are extremely efficient, so I don't think so... the only reasons the turbo couldn't pump enough, would be if there was an exhaust obstruction (not the problem), or a sharp drop in exhaust pressure (which is why I thought of valve float!)
I don't think it is vavle float because when I changed the cam I also replaced the valve springs with #90 pd springs from eastern. Any more guesses guys?