Vacuum Line Replacement

Discussion in 'Fox 5.0 Mustang Tech' started by kpack5982, Mar 8, 2007.


  1. kpack5982

    kpack5982 Yeah, it was pretty stiff, but eventually a buddy

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    I'm trying to locate where I'm having my problem with the vacuum going to egr. (I keep pullin EGR code 33 and I've taken the egr valve off and tested it visually and applying vacuum to it) Problem is that there are so many vacuum lines there I don't know how to go about replacing them. I have vac diagrams and so forth, but my question is all the lines are a brittle plastic style and hook into sleeves, for instance that go to the egr and another to the intake manifold. I'm talking about the vac lines on the passenger side of couse, where they route into the evr I believe and the separator, where like 4 lines go in and 4 out. I actually only have two that come out, the ones to the smog equipment have been capped. I haven't been able to find the brittle plastic hoses at local parts stores, but can I directly run like the thicker rubber lines directly from one place to another? And does anyone have any pictures of the area and how their lines are run? Thanks in advance. :SNSign:
     
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  2. the pony boy

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    it matters which way you put the vac lines in the evr.try pulling the codes and than pull the neg cable for 10 minutes switch the lines going into the evr and try it that way.i found the hard vacuum lines at advanced auto.i plan on doing the lines over when i have time. good luck phil
     
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  3. jrichker

    jrichker StangNet's favorite TOOL
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    Diagram courtesy of Tmoss & Stang&2birds
    [​IMG]

    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

    Ignition switch wiring
    http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

    Fuel, alternator, A/C and ignition wiring
    http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

    Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

    Vacuum diagram 89-93 Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
     
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  4. kpack5982

    kpack5982 Yeah, it was pretty stiff, but eventually a buddy

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    well poopy. I checked the codes and got 12, 41, and 33. I didn't get to the partstore tonight in time to get some new vacuum hosing, but I'm gonna guess a vacuum leak. I may have another issue with a leak on the passenger side valve cover too, I dunno, but what do you guys think? My car is in a friend's car garage about 30 miles away from my place and about 30 mins from a partstore so anything I need or you could suggest would be good.
     
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  5. Roland69

    Roland69 Sergeant Tangnet

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    get a shop to hook it up to a smoke machine
     
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  6. jrichker

    jrichker StangNet's favorite TOOL
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    Code 12 -Idle Air Bypass motor not controlling idle properly (generally idle too low) - IAB dirty or not working. Take it off and clean it thoroughly with throttle body cleaner. Clean the electrical contacts with non flammable brake parts cleaner at the same time.

    Code 33 - Insufficient EGR flow detected.
    Look for vacuum leaks, cracked vacuum lines, failed EGR vacuum regulator. Check to see if you have 10” of vacuum at the EGR vacuum connection coming from the intake manifold. Look for electrical signal at the vacuum regulator solenoid valves located on the rear of the passenger side wheel well. Using a test light across the electrical connector, it should flicker as the electrical signal flickers. Remember that the computer does not source any power, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.
    Check for resistance between the brown/lt green wire on the EGR sensor and pin 27 on the computer: you should have less than 1 ohm.

    See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

    http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

    http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif


    EGR test procedure courtesy of cjones

    to check the EGR valve:
    bring the engine to normal temp.
    connect a vacuum pump to the EGR Valve
    apply 5in vacuum to the valve.
    if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.
    if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.
    if engine stumbled, connect vacuum gauge to the hose coming off of the EGR Valve
    snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
    did the vacuum gauge show about 5in vacuum?

    if not, check for manifold vacuum at the EGR vacuum valve.
    if you have manifold vacuum then connect vacuum gauge to the EGR valve side of the vacuum valve and snap throttle to 2500 RPM.
    should read about 5in vacuum

    The operation of the EGR vacuum regulator can be checked by using a test light applied across the wiring connector. Jumper the computer into self test mode and turn the key on but do not start the engine. You will hear all the actuators (including the EVR vacuum regulator) cycle. Watch for the light to flicker: that means the computer has signaled the EGR vacuum regulator successfully.

    Some basic EGR theory to clarify how things work is in order…

    The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions. A custom tune & chip are needed to disable the EGR functions in the computer.

    The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

    There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

    Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)
    [​IMG]

    The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.


    Code 41 or 91 - O2 indicates system lean. Look for a vacuum leak or failing O2 sensor.

    The computer sees a lean mixture signal coming from the O2 sensors and tries to compensate by adding more fuel. Many times the end result is an engine that runs pig rich and stinks of unburned fuel.

    The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
    "When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

    When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

    Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

    Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

    Testing the O2 sensors
    Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.

    Testing the O2 sensor wiring harness
    Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer.

    Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

    The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

    Replace the O2 sensors in pairs if replacement is indicated. If one is weak or bad, the other one probably isn't far behind.


    Fix your broken and misrouted vacuum lines and the above codes will probably go away.
     
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  7. glowstang93

    glowstang93 Member

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    I have been replacing my brittle vacuum lines with vacuum line tubing that looks like small rubber hose, but is labeled vacuum line. With the correct size, it just slides onto the air tree or evr without the need of the connecting pieces that the plastic tubing had. It is also going to last a whole lot better than that old plastic. I got mine from Car quest, but im sure all auto parts stores have some in a bag or by the foot.
     
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  8. 4G-KDMP

    4G-KDMP Member

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    i never new that... thanks
     
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