1991 Mustang 5.0 Vacuum Hoses

Blueinfan · Mar 25, 2021

Hi All, This might be like the 10th or so posting on Vacuum hoses. I've looked at some of the posting and diagrams on here and still doesn't see it. Hope the way I've added will help.

I've added some pics to confirm the hoses.

1. First pic, shows the EGR hose going to the middle hole in the Vacuum Cube.
2. Second pic, Vacuum tree hose that runs along the firewall to the passenger side.
3. Third pic, Hose coming from the vacuum tree. Where does it go on the Vacuum cube?
4. Forth pic, Valve that is right beneath the throttle body. Where does this hose go on the cube?
5. There is another hose that comes from a valve close to the Charcoal box. Where does this hose go on the vacuum cube?
6. Last pic with numbers on cube holes - I have taken a picture of my cube and have added numbers.

I know a lot of people have the same question as I do and hope this info will help others by the pics and the numbers associated with each.

thanks for your time.

General karthief · Mar 25, 2021

This may help you a little:

1990 5.0 Mustang vacuum/emissons issues

Help! I just purchased my 1990 Mustang 5.0, 5 speed, original "7-Up" convertible and it had been non-operational since 2001. In evaluating this 61 K original miles beauty, the previous owner had done some R&R on the lines that attach to the plenum chamber and I am at a total loss of how to...

www.stangnet.com

Mustang5L5 · Mar 25, 2021

Dont think he was asking a question. He was putting this info out there

Blueinfan · Mar 25, 2021

Mustang5L5 said:
Dont think he was asking a question. He was putting this info out there

I will have to print it out and check the diagram. The previous owner did not know what he was doing. I've replaced all the hoses and now don't know how they go.

Andrews24 · Apr 19, 2021

I want to replace hose from pic 1... I cannot find it for sale

Blueinfan · Apr 20, 2021

Yes, go to Autozone and ask them to show you 5/32= stock# 47418 and 1/8 #47417. O-Reilly's should have them too. I looked and researched the out of this. The vacuum hoses in my car were all dry rotten and old.

I also ordered some from Ebay. I also bought

AUTOBAHN88 Engine ROOM Silicone Air Vacuum Hose Dress Up Kit BLACK Fit TOYOTA | eBay

<li> Brand autobahn88 Manufacturer Part Number ASHU06-Kit-BK-toyota-01 Vacuum Hose Included 3mm - 3meter/10', 4mm - 2meter/6', 8mm-1meter/3' Others Included Zip Tie 30pcs , Spring Clamp Kit , Plastic T-Joiner 3pcs Color BLACK QTY 1 Pack as described - BEST BUY in Town Application Boost Hose...

www.ebay.com

I just made them work.

mattys91gt · Jul 23, 2022

I'm trying to figure out what way to run lines for a new EGR and vavle I got or no EGR on and keep the vavle plugged in and shut halfway

Pinellas50 · Jul 23, 2022

Here's a vacuum diagram.

mattys91gt · Jul 23, 2022

Pinellas50 said:
Here's a vacuum diagram.

that's what I have I'm not sure what to run now since alot of stuff got taken off and the check vavle in the middle going back to the evr/EGR solinoid I've never seen that before on my line

General karthief · Jul 24, 2022

All you need if you don't have emission stuff would be PCV, brake booster, fuel regulator,
there are other stuff that needs to work too but this is a start.
I did not mention EGR, TAB/TAD, HVAC or purge solenoid to keep it simple.

mattys91gt · Jul 24, 2022

ok so here's what I have I have a brand new EGR plug and a EGR delete plug with the resistors and block off plate I need to get a soldering gun but still no clue why the intake temp gets so hot I have a temp Lazer gun to see how hot it all gets

General karthief · Jul 24, 2022

What do you mean by your intake getting hot?

mattys91gt · Jul 24, 2022

General karthief said:
What do you mean by your intake getting hot?

the upper intake gets super hot with the EGR on the car and I only have a line from the manifold to the EGR/evr then EGR/evr to EGR and will it hurt to run a high flow thermostat in a stock motor?

General karthief · Jul 24, 2022

What is 'super hot'?
You're not gonna be putting your hand on the intake when the engine is at operating temp, you are likely chasing a problem that is not there, what temps are you reading at the intake?
Is the engine running hot?

mattys91gt · Jul 24, 2022

General karthief said:
What is 'super hot'?
You're not gonna be putting your hand on the intake when the engine is at operating temp, you are likely chasing a problem that is not there, what temps are you reading at the intake?
Is the engine running hot?

150 degree is from idle I'll check after I leave Walmart in a min

jrichker · Jul 26, 2022

mattys91gt said:
ok so here's what I have I have a brand new EGR plug and a EGR delete plug with the resistors and block off plate I need to get a soldering gun but still no clue why the intake temp gets so hot I have a temp Lazer gun to see how hot it all gets

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

EGR System theory and testing

Revised 29-Sep-2013 to add code definitions for EGR sensor and EVR regulator.

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. It does this by reducing the amount of air/fuel mixture that gets burned in the combustion process. Less air from the intake system means less air to mx with the fuel, so the computer leans out the fuel delivery calculations to balance things out. This reduces combustion temperature, and the creation of NOx gases. The reduced combustion temp reduces the tendency to ping.

The computer shuts down the EGR system when it detects WOT (Wide Open Throttle), so the effect on full throttle performance is too small to have any measurable negative effects.

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.

The resistor packs used to fool the computer into turning off the CEL (Check Engine Light) off are a bad idea. All they really do is mess up the data the computer uses to calculate the correct air/fuel mixture. You can easily create problems that are difficult to pin down and fix.

Troubleshooting:
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)

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. A defective or missing sensor will set codes 31 (EVP circuit below minimum voltage) or 32 ( EGR voltage below closed limit).

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid. A defective EVR will set codes 33 (insufficient flow detected), 84 (EGR Vacuum Regulator failure – Broken vacuum lines, no +12 volts, regulator coil open circuit, missing EGR vacuum regulator.)

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 or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

Apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

If the engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

If the engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

If the engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
Snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
Did the vacuum gauge show about 2-5 in vacuum?
If not the EVR has failed

EGR test jig

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

mattys91gt · Jul 26, 2022

jrichker said:
Some basic theory to clarify how things work is in order…

EGR System theory and testing

Revised 29-Sep-2013 to add code definitions for EGR sensor and EVR regulator.

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. It does this by reducing the amount of air/fuel mixture that gets burned in the combustion process. Less air from the intake system means less air to mx with the fuel, so the computer leans out the fuel delivery calculations to balance things out. This reduces combustion temperature, and the creation of NOx gases. The reduced combustion temp reduces the tendency to ping.

The computer shuts down the EGR system when it detects WOT (Wide Open Throttle), so the effect on full throttle performance is too small to have any measurable negative effects.

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.

The resistor packs used to fool the computer into turning off the CEL (Check Engine Light) off are a bad idea. All they really do is mess up the data the computer uses to calculate the correct air/fuel mixture. You can easily create problems that are difficult to pin down and fix.

Troubleshooting:
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)

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. A defective or missing sensor will set codes 31 (EVP circuit below minimum voltage) or 32 ( EGR voltage below closed limit).

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid. A defective EVR will set codes 33 (insufficient flow detected), 84 (EGR Vacuum Regulator failure – Broken vacuum lines, no +12 volts, regulator coil open circuit, missing EGR vacuum regulator.)

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 or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

Apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

If the engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

If the engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

If the engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
Snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
Did the vacuum gauge show about 2-5 in vacuum?
If not the EVR has failed

EGR test jig

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

I keep getting code 34 and I have 3 different Evr and a new one I'm missing a vacuum route or something I pulled like the ball in the fender and the HVAC one is blocked off

jrichker · Jul 26, 2022

mattys91gt said:
I keep getting code 34 and I have 3 different Evr and a new one I'm missing a vacuum route or something I pulled like the ball in the fender and the HVAC one is blocked off

Always check the code definition before replacing parts. It will save time, money and sweat,,,

Code 34 Or 334 - EGR voltage above closed limit –

Revised 26-Sep-2011 to add EGR cleaning and movement test for pintle when vacuum is applied to diaphragm

Failed sensor, carbon between EGR pintle valve and seat holding the valve off its seat. Remove the EGR valve and clean it with carbon remover. Prior to re-installing see if you can blow air through the flange side of the EGR by mouth. If it leaks, there is carbon stuck on the pintle valve seat clean or, replace the EGR valve ($85-$95).

Recommended procedure for cleaning the EGR:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. There is a basket to set the parts in while they are soaking. Soak the metal body in the carb cleaner overnight. Don’t immerse the diaphragm side, since the carb cleaner may damage the diaphragm. If you get any of the carb cleaner on the diaphragm, rinse it off with water immediately. Rinse the part off with water and blow it dry with compressed air. Once it has dried, try blowing through the either hole and it should block the air flow. Do not put parts with water on them or in them in the carb cleaner. If you do, it will weaken the carb cleaner and it won’t clean as effectively.

Gunk Dip type carb & parts soaker:

If you have a handy vacuum source, apply it to the diaphragm and watch to see if the pintle moves freely. Try blowing air through either side and make sure it flows when the pintle retracts and blocks when the pintle is seated. If it does not, replace the EGR.

If the blow by test passes, and you have replaced the sensor, then you have electrical ground problems. Check the resistance between the black/white wire on the MAP/BARO sensor and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1.5 ohm. Next check the resistance between the black/white wire and the negative battery post. It should be less than 1.5 ohm.

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.

Let’s put on our Inspector Gadget propeller head beanies and think about how this works:
The EGR sensor is a variable resistor with ground on one leg and Vref (5 volts) on the other. Its’ resistance ranges from 4000 to 5500 Ohms measured between Vref & ground, depending on the sensor. The center connection of the variable resistor is the slider that moves in response to the amount of vacuum applied. The slider has some minimum value of resistance greater than 100 ohms so that the computer always sees a voltage present at its’ input. If the value was 0 ohms, there would be no voltage output. Then the computer would not be able to distinguish between a properly functioning sensor and one that had a broken wire or bad connection. The EGR I have in hand reads 700 Ohms between the slider (EPV) and ground (SIG RTN) at rest with no vacuum applied. The EGR valve or sensor may cause the voltage to be above closed limits due to the manufacturing tolerances that cause the EGR sensor to rest at a higher position than it should.

The following sensors are connected to the white 10 pin connector (salt & pepper engine harness connectors)

This code can affect idle quality by diluting the intake air charge

1991 Mustang 5.0 Vacuum Hoses

Active Member

Attachments

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

Active Member

Active Member

Active Member

Active Member

Active Member

Attachments

Active Member

wonder how much it would cost to ship you a pair

Active Member

Attachments

wonder how much it would cost to ship you a pair

Active Member

wonder how much it would cost to ship you a pair

Active Member

StangNet's favorite TOOL

Active Member

StangNet's favorite TOOL

Similar threads

Privacy & Transparency

Privacy & Transparency