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Discussion Starter #1
I have a 86 Shelby with the only mods being a hi-flow cat and straight 2.5" exhaust. A few days ago it started hitting overboost at WOD but does not throw any codes. I have a boost gauge and when o/b hits it is over 15lbs. Where should I start?:confused:
 

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Do you have a manual boost controller? Are you running a Muffler that will produce any backpressure, or is it free flowing? When I threw my 3 inch on, I had to reset everything. Manual Boost controller I made from scratch for 5 bucks works wonders, and has been for a while.
 

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Discussion Starter #3
No manual boost controller or muffler. I've had 2.5 from the cat back for a few yrs. one day it just starts boosting to over 15lbs on the MP computer and the stock computer. It sat a couple months with 1/2 tank of gas but it's now full. At 1/2 throttle it runs good. Can vac leaks cause overboost?
 

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check your vac lines, I had the same problem, when I hit overboost it blew the rear cam seal out of the motor. The line that goes to the wastegate broke (old/brittle) Also make sure the "orifice" /restrictor(s) are there.
 

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Discussion Starter #5
Cool I'll check all the vac lines. How stiff should the wastegate arm be? Mine will only move by hand with a lot of force and then only less than 1/4".
 

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OK. I found my problem and created a much bigger one:bang head. The vacuum line at the wastegate was broken and most likely causing the overboost. While trying to replace it, I broke all the little brittle plastic lines that are bundled on top of the manifold. I have a copy of the vacuum diagram and can't make much out of it. There are about 6 of these little lines coming out of a thing I can only describe as a connector plug, that joins more lines connecting the various solenoids on the right side fenderwell. 4 of these lines go into a 4 to 1 vacuum source on the intake. 1 goes to the TB and the other goes to the wastegate. My problem is I can't tell which is which and like I said the diagram confuses me even more. Is there a simple way to do this? What's the "secret key" to the diagram?
 

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Discussion Starter #8
Thanks. That does look easier, but does that require I put in a BOV? Also what does VC and FPR stand for? I'm new to these turbos and pretty much need all the help I can get.
 

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Discussion Starter #10
Thanks aRTIe. If I attempt the simplified setup What do I do with all the extra lines? Are they just capped? Am I making this more complicated than it is?
 

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There are some more lines you can or may want to hookup. The lines that i am pretty sure you have left over are the ones for the purge canister, your call on if you want those hooked up. If your boost is still controlled by the computer you will need to hook up the boost control solenoid. As far as capping lines, you don't want an open vacuum lin into your motor, so if they are going to the motor cap them if the are going to something that you don't hookup (like the purge canister) you could probably leave those open.

I personally would try to follow the factory diagram and make sure you are not missing something. diagrams can be found here. www.thedodgegarage.com under the turbo datatbase.
 

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I would rather follow the factory diagram but that's the problem. I can't see how it matches what I see on the car. Anybody give lessons?
 

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I think you are making it too complicated in your head. You basically have one vacuum source (intake manifold) and you have several things that need a vacuum line ran to it. The simplified drawing is a good indication of how simple it can be.
http://www.thedodgegarage.com/turbo/turbo86.jpg
on this diagram see where all the lines come together where it looks like a nut. that is the source, it should be a fairly large fitting on your intake, the individual lines can be Tee'd from there for *most of what you need to hook up. there are a couple from the throttle body that need to be hooked up as well.

The solenoids are about the size of a film canister and have three barbs on them, where they say bleed that is the barb with a small foam filter on it.

the orifices are small, you wont really see them they look like apiece of plastic that someone might have used to patch together a line.

The check valves are a small disc shape with a barb on both sides (crappy description) on the diagram it shows you which way to point them (they only flow in one direction) you can blow through it to see how they work.

Then just take your time and you will figure it out. It seems intimidating if you have never done it, but its not too bad.
 

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Discussion Starter #14
Thanks again aRTie! That really helps. I can make more sense of it now that I see where the source is shown on the diagram. I'm going to give it a try next week.
 
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