Engine Vacuum problem

Dirtnastyfox

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Mar 15, 2019
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I’ll make this as short as possible. Basically I plugged off all my unused vacuum ports on the “vacuum tree” and it bogs down like it wants to shut off once it’s warmed up. But it runs good at idle. But if I pull a couple of them off it doesn’t shut off but idles down a lot and runs worse. Any ideas??
 
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jrichker

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Mar 10, 2000
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Dump codes sticky

Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. Codes may be present even if the CEL (Check Engine Light) isn’t on. You don’t need a code reader or scanner – all you need is a paper clip, or if your lady friend has a hair pin, that will do the job.
I highly suggest that you read it and follow the instructions to dump the codes. http://www.stangnet.com/mustang-forums/threads/how-to-pull-codes-from-eec4.889006/
 
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mikestang63

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Aug 27, 2012
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the car is supercharged and you randomly started plugging vacuum hoses? Why were there open ones? One was not the BAP/MAP sensor that you capped?

Take some pictures and post them underhood

In General terms you need vacuum going to the folllowing
FPR
Brake Booster
PCV valve
Boost gauge
Boost blowoff valve
Cruise Control
HVAC controls
Charcoal cannister

with a supercharged application you normally want an open valve cover breather, cap off the breather tube and bung on the Throttle body and then a check valve from the PCV to the breather and the PCV and screen, or no PCV and breathers in the PCV hole and valve cover and cap off the bung on the intake.
 

Dirtnastyfox

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Mar 15, 2019
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The middle three lines on my car aren’t there. They were just open when I got it. This is not my car it’s just a google picture. But that’s basically what I did was cap all three of the middle ones and it rand good but after it would get warm it would shut off. Then I pulled a couple of the caps off and it ran a little rough but wouldn’t shut off or anything.
 

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Blucifer99

I only understand every 3rd word
Jul 15, 2018
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Just a guess. But sound like its drowning in fuel... Adjust your throttle screw abit and see if that helps.. But what exactly is the car doing? When u first start it. Does it fire normal then as it warms up drop in revs and then stalls out? Or does it chug along until it dies. Also what happens when u hit the gas. Does it stumble?
 

Dirtnastyfox

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Mar 15, 2019
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Just a guess. But sound like its drowning in fuel... Adjust your throttle screw abit and see if that helps.. But what exactly is the car doing? When u first start it. Does it fire normal then as it warms up drop in revs and then stalls out? Or does it chug along until it dies. Also what happens when u hit the gas. Does it stumble?
Well it’s been running great for the last few days. Apparently I was only running 30 psi to the fuel rail. Adjusted that and it runs great but still if I plug the vacuum tree that I’m not using it idles up and down and when you give it gas it shuts off immediately.
 

Mustang5L5

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Firewall dead center. If the car is still stock speed density, there should be a vac line connected to the manifold

does the car have a mass air meter?
 

Blown88GT

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Nov 13, 1999
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This shows how to "modify" the MAP sensor when converting to MAF.
If you are still SD, it will show how it should be, i..e vacuum line connected to MAP sensor.
 

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