Won't go over 15-16 psi

[GLHS592]

I have a boost problem with my Shelby Charger. It just won't go over 15-16 psi no matter how far I crank on the grainger valve. In fact, I have it cranked all the way in. I have been suspecting that it was the DSM blow off valve, but I have heard they leak at 18-21 psi. I've swapped a crushed one on, but haven't had the time to test it out. I've also considered that maybe it's my wastegate can. Well, it held 20 psi on the old setup.

Since the car is in storage and I'm couped up in this tiny apartment awaiting our house to be built, I've had alot of time to think about it. It hit me the other night that when I put the SDS stand alone in the car, I never re-routed any of the vacuum lines except for the one coming off the intake manifold to the MAP sensor. So, there are still some lines going to the evap. and MAP solenoids that aren't being used and need to be tossed in the trash can. Would those solenoids pop open and cause the boost to top out at 15-16 psi?

[turbovanman²]

No, the solenoids are closed when not enerigized, even if one is leaking, the leak would be so small you could still boost over 16 psi. Sounds like your can is weak. If you have a vacuum pump, lock the wastegate can with it and see what happens. Thats how I used to max out my TIII turbo, :thumb:

[SpoolinGLH]

Try taking the grainger apart and cleaning it , then stretch the spring alittle bit and just put it back together. I had to do that on mine to achieve 19psi because the springs are weak.

[GLHSKEN]

+1 on the cleaning... The vent hole gets clogged and keeps it pressurized... Open real easy then ... like minimum boost with direct vacuum source.

My car finally hit the welder last weekend... Rad support k frame, floors (thank you again), rear 1/4's and look at stiffening anything he can.

[GLHS592]

I have a stiffer spring I'm going to put in the grainger. About the WG can. It held 20 psi when I was still running the stock engine converted to turbo 2. I only used it because I was out of money, for the good one Chris W. sells, at the time. Thanks for the ideas.

[Force Fed Mopar]

If it's the wastegate getting weak, you could try shimming it w/ some head bolt washers. Both me and DodgeZ have done it, his GLHS was hitting 23 psi.

I had been told that stock and un-shimmed the small cans were only good to 15-16 psi.

[GLHS592]

This can is a big 1985 model. I'm not sure I can shim it considering the way I have it mounted on the hybrid turbo. I might be able to put some kind of spring on it to hold it back.

[Dave]

+++1 on cleaning the G-valve. Happened to me on my HP Performance boost controller. Turns out the check ball in there would get clogged in the line directing to the WG can (with the orifice tapped in) and would limit my boost to the lowest setting.

[2.216VTurbo]

Great suggestions but they missed the obvious, that high dollar hybrid turbo you have is blown, I'll give you a couple hundred bucks for it :lol: I'm just trying to help...:evil:

[8valves]

Kevin, to eliminate a lot of possibilities, get some hevy duty bundling twine/mechanics wire and wire the wastegate flapper flush and shut as tightly as you can. This will elminate any boost leaks of sorts as being the problem if the boost builds past 15/16. Just be cautious, as once the 50 trim starts to get into it's sweet spot, right around 15/16, boost will come one SUPER FAST, so as soon as it sweeps past the point where it used to stop off the throttle, as I'm sure you can figure on yourself, just it's tough to envision how fast it starts climbing with a totally shut wastegate.

Also, this points you towards the control system for boost, or the wastegate actuator itself. Then you can try cleaning the MBC out and seeing if that works, or trying a different boost controller from someone else, etc.

Aaron Miller

[89DaytonaTII]

I've had similiar issues where the cause turned out to be a weak spring in the g-valve.

[GLHSKEN]

To solve a weak spring, Take a 1/4" ferule (spelling) from like an ice maker line (hollow in the middle), drop it into the bottom and put the spring on it. Works wonders.

[GLHS592]

Thanks! I might get a chance to fool with it this weekend if I can get the new dash in the car (halfway through that swap) and it doesn't rain.

[SpoolinGLH]

Thanks! I might get a chance to fool with it this weekend if I can get the new dash in the car (halfway through that swap) and it doesn't rain.


bet you cant wait for a garage!:D

[GLHS592]

You ain't kidding. Me and the wife took a day off from work and went to my parents' house for the weekend. I got the dash back in the car. I just got a few things to put back and I'm ready to roll. Rain shouldn't be here until after noon. I swapped a heavier spring into my boost controller and cleaned it out.

[SpoolinGLH]

Let us know how that worked..

[GLHS592]

Like I said, I swapped on another DSM BOV that is crushed a little and swapped a heavier spring into my boost controller. I also cranked the boost contoller all the way in. Well, the boost gauge showed 20-21 psi. Of course, I think my gauge is off a little, but it was showing 16-17 psi before.