I have a quick question maybe someone can give me some in site into.
I have a t3/t4 external gate. and for the longest time i ran the gate straight pipe to the ground. well i had cracked my manifold so i figured if i was going to tear it all apart i might as well make the waste gate return to the down-pipe like normal cars, plus it was getting kinda loud and i was tired of hearing it when the waste gate opened. now for the basics. I was running 9 pounds of boost. in 4th gear it would peak 10 but never more, i never had spiking or creeping my WOT was always 9 psi once it built boost. So last night i put it all back together. and now i hadn't touched my boost controller it was still at 9 psi. When i spool it up it climbs to 9 and drops back to 6sh at wide open throttle.
But when i do a 4th gear pull at wide open throttle it will hold 10 pounds all day long. Now it was really starting to bother me so i turned my boost controller up to 13 psi and its the same thing. 3rd gear will just leak it way back down to 6 psi. my stock waste gate spring is 6 psi. So im figuring that my boost controller witch was a home depot special has finally taken a death turn. also my car normally at idle would be somewhere around -21 psi manifold pressure it now rest at 18-19 ish. So i figured it was an intake manifold leak. So i took a pressure tester to the intake manifold and carb cleaner when it was running and found no leaks. i didn't pressure test the whole charging system because my charge pipe is nearly impossible to get to at the the turbo without removing the down-pipe turbo and manifold.

I am kinda at wits end with it. because it seems like a boost leak issue but it doesn't do it in 4th gear. or at least seem like it is, I already checked and double checked all my t-clamps and hose couplers it seems like the boost controller is holding the 9 psi back from the waste gate then just letting it thru and dropping it back down to 6 because it holds 6 fine. and like i said before even when i turned the boost controller up higher it still drops back to 6 , if i was making 9 psi and i had a 3 psi leak then it would be 6 but if i making 12 psi shouldn't the number if it was leaking be higher than 6...


please help


Chris

listening... I have a similar problem...




2004 Cavalier
13.2@105........
Mods...
BFG Drag Radials
Saab Turbo kit
2.5 exhaust, w/cutout
Spec Stage 2+ Clutch

Remove the controller and run just off of the WG. If it will hold the pressure that the WG is set to then the controller is bad.

That is all i can think of if you have already checked all of your connections in the piping.

it holds the stock pressure i know that for sure. The stock psi 6 it holds 6 but im just wondering if its the waste gate regulating it to 6 or the waste gate is letting it make 10 but is leaking to 6 . follow what im saying. Im going to replace the vaccum lines from the waste gate to the turbo tomorrow and get a new neddle vavle since thats what im using for the boost controller. it worked excellent intill last night . im thinking i might have just messed it up or something. all i know is it runs like a hog at 6 psi. 9 was way way better lol.......

Plus its tuned for 9 so its really runnning pig rich when im in the throttle hard.

Take it for what it's worth but I'd say it's no coincidence that the pressure happens to leak down to 6 PSI, same as your wastegate setting if I read correctly. You should find something with that boost controller. If it was a boost leak on a charge pipe it should leak all of the time.

I think I might have a suggestion. I'm building my car right now so I'm not an expert at this stuff, but here is my suggestion.

Your home made manual boost controller should have a small hole in it on the wastegate side, that way when you change gears and the wastegate is going from open to closed you do not trap air or boost signal between your controller and valve. It needs a way to leak down or off completely. I think what is happening is that air is trapped in your signal line following your shift and slighly holding your gate open...this is my two cents. Hopefully it helps.