Crazy boost!!!

[Mopar_Nutz]

Well I guess it's a boost related topic even though I'm guessing it's a computer problem.

The car;
87 Shelby Charger. 2.5 T1 on GLHS Stage II LM. +20% injectors. TII turbo and all the other common stuff.

The "problem";
In lower gears, at WOT it'll boost to roughly 9 psi and hold steady. If I ease off the throttle, the boost goes crazy and will spike up to 20+. In 5th gear I matted it and the boost steadily climbed to 25 psi (EGT's never went over 1350). If I let it, it'll peg my 30 psi gauge. Now this sounds like fun but with no IC yet, and no extra fuel other than the +20's, I'm sure damage will be the next stop.

Boost is controlled by the computer, so I'm assuming thats where the problem lies. Any other ideas? The only thing that makes me think computer is because it will stay at 9 psi at full throttle if I'm in gears 1-3 or so.

I'm thinking the only choice I have is to throw a boost controller on it, but I hate taking power away from the computer when I'm running IC-less. I like that it can pull timing if it has to, but CLEARLY it's not pulling boost.

[turbovanman²]

Hook it up to the intake and see what happens. Do you have the restrictor in place?

[mark]

i had similar problem years ago, the WG control vacum line (the hard plastic one) was rubbing on the frame and actually punctured it.

[Mopar_Nutz]

Ya know, I'm not sure if I actually put the restrictor in or not. I just slapped it together in the dark haha.
I do know the lines are all good though. No leaks or holes.

[omnivore]

you went 20+ psi with no IC? DUDE!!!

[Force Fed Mopar]

Check how you have the lines run to the wg solenoid, the bottom nipple should be uncapped, and the line from the intake to the solenoid should go in the top, and the one from the solenoid to the wg can should come out the side. Here's a diagram Solenoid Pack Vacuum Routing

[Mopar_Nutz]

you went 20+ psi with no IC? DUDE!!!

Yeah I know. I do have it mounted but I'm still waiting on the pipes to plumb it. Dicey stuff eh? MAN it hauls though. Absolutely RIPPED an 89 Daytona Shelby tonight on 14 psi (MBC in now)

[Mopar_Nutz]

Hook it up to the intake and see what happens. Do you have the restrictor in place?

I didn't have a restrictor in it, but I put one in and it's still doing it. I stuck a boost controller on it for now to keep things within reason.

[Mopar_Nutz]

Check how you have the lines run to the wg solenoid, the bottom nipple should be uncapped, and the line from the intake to the solenoid should go in the top, and the one from the solenoid to the wg can should come out the side. Here's a diagram Solenoid Pack Vacuum Routing

The link isn't working for me but I'll double check the lines tomorrow morning. It's still got the factory hard plastic ends on it, but I'll make sure it's routed right. I'll just blow in the line and make sure it's venting by default.

I should mention that with the old engine (2 months ago) it was perfectly fine. This was with the 2.2 TII setup on the same computer. So it's a bit strange that it's suddenly boosting like this when I put it back together with the 2.5 block.

[Dave]

Why not run the MBC? Complete control and faster spool... it's a win-win situation. Shoot mount it in the cabin too for lazy control.

[Mopar_Nutz]

I might just do that. 2 reasons why I haven't. One, I wanted the computer to control it to be "safe" with no IC. So much for that idea though! hahaha

And the other....I just hate when things aren't working right so wanted to solve it if possible. Doesn't seem right just ignoring a problem. Ah well. When the IC gets plumbed it'll be dual stage boost from then on out anyways

[Dave]

Trust me, it's not ignoring the prolbem. You can't control boost, so you install a device that will. . . a MBC.

Also, a MBC is one of the safest devices you can install to ensure your safety. If hooked up properly, ie - install small clamps on every barb! EVERY BARB, DAMNIT! Hoses will blow off if you run enough boost and the WG can will be open to atmospheric pressure and the WG will slam shut and there goes your control... hello turbo's limit to how many psi it can produce. Use the same size line, and make sure the barb that has the orifice to bleed the boost is closest to the WG can.

G'luck.

[Mopar_Nutz]

Ok I'm thinking I may have a sticky wastegate or something. It's still doing the 20+ psi spike when I first get on it. Seems to spike pretty bad in 1st and 2nd but generally settles down by 3rd or when I get back on it. The WG felt alright when I put it on but I'll check it again tomorrow when it's cooled down.

IC PIPES ARE HERE TOO! So I can get that NPR plumbed in now