Can only make 18 lbs of boost

[DougsfastZ]

So a few months ago a had the car dialed in at 23 lbs of boost on the stock turbo and running good. I had a boost fluctuation issue and figured it was the stock wastegate actuator since I heard they are only good for about 20lbs. I ordered a brand new HD actuator with an adjustable rod. I'm (and have been) running a RJC boost controller. Since I installed the HD actuator I haven't been able to build more then 18 lbs of boost. It doesn't matter how I adjust the boost controller I can't get any more. Plus the only way to build that amount is if I have the rod threaded all the way in. If I set the rod in order for me to pull it a 1/4 inch ito get it on the puck, I can only build 8 lbs. I have checked all vacuum lines and intercooler piping and it all checked out. The only thing I can think of the puck isn't sealing, but I'm on a stock turbo with a brand new THDP 3" DP (with a 1.375" puck). One thing though, on one of my test passes yesterday I did build 23 lbs, but was never able too again.

Any ideas?

Doug D

 

[TURBOELKY]

thought

have you tried to bypass that boost controller crap? take it off and try that, maybe it went bad. I read they spring a leak occasionally. That hd actuator starts at 18, I had a problem when I had mine that I could not go under 18psi, and that was with a t66. Go external, you'll be able to adjust properly then....

 

[LUCKY1313]

have you tried to bypass that boost controller crap? take it off and try that, maybe it went bad. I read they spring a leak occasionally. That hd actuator starts at 18, I had a problem when I had mine that I could not go under 18psi, and that was with a t66. Go external, you'll be able to adjust properly then....

Unhook all the vacume/boost lines going to the wastegate acuator. If it still doesnt go to full boost ( and it will if everything is working right so be ready to let of the throttle if it takes off with the boost) then there is a problem with the turbo,gate or some kinda leak or restriction.

So if it dont boost either the puck is not sealing (could be out of line and not covering the hole)
Or maybe cracks in the turbo housing at the hole and it cant seal.
Turbo wheels are bad and it cant make that much boost (to much clearance,or bad fins on wheel )
Exhaust has leaks and it cant drive the turbo good enough to make the boost. (leak ay header or crossover)
Exhaust has a restriction and want let enough exhaust flow to drive the turbo(cat stoped up, muffler baffle moved or loose.
Leaks in the charge side piping or intake (you said you checked this)
Engine is running so poorly it dont have enough exhaust to drive the turbo.


You should find your problem in one of these area's if it want make boost with the wategate hoses unhooked. If it does go full boost then the problem is in the acuator or controller. But It probably want make no more boost with all you said you tried.


Jess

 

[Clark6]

You may have an exhaust leak like he said do you have the stock headers,crossover, etc. CHECK YOUR CROSSOVER PIPES FOR LEAKS, AND THE TURBO TO HEADER FLANGE.

 

[Underboost]

So a few months ago a had the car dialed in at 23 lbs of boost on the stock turbo and running good. I had a boost fluctuation issue and figured it was the stock wastegate actuator since I heard they are only good for about 20lbs. I ordered a brand new HD actuator with an adjustable rod. I'm (and have been) running a RJC boost controller. Since I installed the HD actuator I haven't been able to build more then 18 lbs of boost. It doesn't matter how I adjust the boost controller I can't get any more. Plus the only way to build that amount is if I have the rod threaded all the way in. If I set the rod in order for me to pull it a 1/4 inch ito get it on the puck, I can only build 8 lbs. I have checked all vacuum lines and intercooler piping and it all checked out. The only thing I can think of the puck isn't sealing, but I'm on a stock turbo with a brand new THDP 3" DP (with a 1.375" puck). One thing though, on one of my test passes yesterday I did build 23 lbs, but was never able too again.

Any ideas?

Doug D

I had this problem. But my car was running hard at 12psi. I couldn't figure it out, it was driving me crazy. I took the car to Lou Czarnota he found the Vacuum lines at the vacuum block above the throttle body were all cracked underneath. These cars are old. You can't tell unless you take them off and bend them.:wink:

Post what you find out.