1994-95 mustang gt vacuum

Yellow94Gts · Jul 1, 2024

Does anyone know what vacuum lines and where they would be routed behind the dash of my gt are? I’m being told that there’s some routed behind my dash and I just want to make sure before have to remove my dash to check on them and if they are intact I am reinstalling my egr as I cannot find a solution to my high idle with this egr removed

Mcmahst · Jul 1, 2024

While I’m no expert, the only vacuum line on the passenger compartment of the firewall is the HVAC control system vacuum source.

WhiteCobra95 · Jul 6, 2024

I checked the vacuum diagram from the underside of my hood, but it doesn't show the breakout for the HVAC. This seems limited to the emission / engine controls only. If I had to guess, I would suspect it's coming from the reservoir behind the check valve. If I can find my other manuals, I'll look deeper to verify. I've never had to mess with those lines on my car, but it's a good thing to know.

Mcmahst · Jul 6, 2024

I guess I’m not sure why you’re worried about the passenger compartment vacuum lines if you’re reinstalling the EGR. The EGR uses a vacuum regulator to open and close it. Those lines are part of the TAB/TAD valve manifold vacuum source. Any lines that go into the passenger compartment are not related or connected, as in function, to the EGR system.

Yellow94Gts · Jul 7, 2024

Mcmahst said:
I guess I’m not sure why you’re worried about the passenger compartment vacuum lines if you’re reinstalling the EGR. The EGR uses a vacuum regulator to open and close it. Those lines are part of the TAB/TAD valve manifold vacuum source. Any lines that go into the passenger compartment are not related or connected, as in function, to the EGR system.

Only checking them to see if I have busted line some where just in case so I don’t reinstall the egr if I dont have to cause I can’t seem to get my idle figured out

Mcmahst · Jul 7, 2024

Well, when you think about it, a proper functing EGR valve only works, essentially, while you’re cruising, not at idle. But, for me, I don’t understand why folks remove them, since they improve fuel mileage, are not on at WOT or at idle. Most of the idle issues in these cars are vacuum hose related. I don’t think Ford could have put anymore hoses on that engine. My idle issue turned out to be a set of vacuum hose issues. So, at idle, what does your vacuum gauge say? I would start there, skip the EGR reinstall for now. Once you’ve track down and solved that problem, you can put the EGR valve back on. Good luck, you’re gonna figure this out.

maillemaker · Jan 3, 2025

WhiteCobra95 said:
I checked the vacuum diagram from the underside of my hood, but it doesn't show the breakout for the HVAC. This seems limited to the emission / engine controls only. If I had to guess, I would suspect it's coming from the reservoir behind the check valve. If I can find my other manuals, I'll look deeper to verify. I've never had to mess with those lines on my car, but it's a good thing to know.

Thank you for this color-coded version of the vacuum diagram! I have been chasing an EGR valve code for a few months now and it turns out my EGR and MAN VAC (green/red) lines were reversed (near the EGR valve)!

Someone at some point had disconnected manifold and EGR and when they plugged them back in got them backwards. Might have even been me!

Mcmahst · Jan 4, 2025

Good for you.

Noobz347 · Jan 4, 2025

maillemaker said:
Someone at some point had disconnected manifold and EGR and when they plugged them back in got them backwards. Might have even been me!

That's how I know I worked on stuff before.

1994-95 mustang gt vacuum

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