94ford5liter

I have a couple questions about the vaccum lines on a 1994 5.0. The plastic line going to the EGR valve and the one next to it going to the intake manifold have no vaccum, so i figured i better replace them. I know they go into the passenger side fender, where do they come out and how hard are they to change?

94ford5liter

anyone??

Derf00

Easy to change but if they are preformed lines you may have to go to the dealer. Before you go changing those lines, what usually fails is the DPFE (Differential Pressure for EGR) switch. It's black somewhat flat and squarish, typically has one or two vacuum lines attached to it as well as in-line with the EGR metal tubes.

Not sure about 94 but my 00 has an Air pump in the passenger side fenderwell. There is a solenoid on top of it that may need replacing but I've never heard of anyone needing to service it.

grabbem88

sorry wish i could help,but i yanked all that stuff off...i'm not %100,but doesn't one of them go to the charcoal box??or is it just the intake,and gas tank that goes to it?

94ford5liter

Wouldnt an error code of came up on the diagnostic check if it was the DPFE?

Derf00

It definitely would on an OBDII but I haven't had much experience on an OBDI with the DPFE. You would get a light with no vacuum too on an OBDII as it would cause leaning out. Have you tried to see if there are any codes stored even with the light off?

Also, when you check the vaccuum from the Intake, is it with the engine idling or with you manually opening the throttle under the hood? At idle you shouldn't feel much of anything. At moderate RPMsis where the most vacuum would be felt. Even then you would need a vacuum guage to get any idea of how much there actually is.

As part of replacing the vacuum lines, you could pop the EGR valve off and clean it out.

94ford5liter

well at idle i used a vaccum tester and there was no vaccum at all in either of the lines.

vfast

but what is it when you give it gas correct?

lunchbox99

egr doesnt get vaccum until your cruising under light throttle. and the vaccum line that goes INTO the intake manifold? explain?

Derf00

There is always suction at the intake. I think what was meant was it's too low to register until you open up the throttle a bit. Vacuum is created by the Intake manifold (air gets sucked into the engine) there are a couple of lines that come off the intake to various components. At idle there isn't enough vacuum caused by the air rushing into the engine to really register on a vacuum pump. As you increase the throttle, so does the suction (increase). If one of these lines is plugged or broken it would cause a loss of vaccuum in the lines that run to the EGR system. Using a vacuum tester woudl tell you if there's vaccuum or not.