Smog Equipment Removal--need Advice!!!

Discussion in 'Fox 5.0 Mustang Tech' started by 1992MustangGT, Jan 24, 2014.


  1. 1992MustangGT

    1992MustangGT Member

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    I have a 92 Mustang GT 5.0 that is mostly stock except for a bigger throttle body and CAI. The smog pump is going out and instead of replacing it I would like to just remove the entire smog system. Can someone out there tell me how to do this? I need someone to tell me what equipment to remove and what additional things I need to do to accomplish this besides just removing parts, if any. I need someone to lay out everything from A to Z on what to do?

    1) Will I need to reprogram the computer or buy some sort of component to install after I remove the smog components?
    2) I'm sure I'll need a shorter serpentine belt once I remove the smog pump. Do I need some sort of delete kit with a idler pulley or can I just buy a shorter belt?
    3) Will I need to modify any wiring? I read about how to do this years ago, but I don't remember what the article said to do.

    If my memory serves me correctly, all I need to do is remove the smog components without any additional modification...Is this correct?

    4) If all I need to do is remove the smog components, can someone tell me what component to remove and where exactly they're located? I know where the smog pump is and the hoses that are connected to is are obviously part of the smog system. But what other components do I need to remove?

    Thanks in advance for your help....
    #1
  2. 88LX5.Oh

    88LX5.Oh Advanced Member

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    You'll gain nothing by removing it except an annoying CEL and I've even heard of people getting drivability issues by removing smog equipment. Best thing to do is to just go to a junk yard and buy a replacement.

    But if you really want to go ahead and do this, I can look for my belt length. I removed my smog pump and just ran a shorter belt, I have my belt length written down in my tool box at work so I can get back to you tomorrow on that
    #2
  3. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Removing the pollution control equipment from a 5.0 Mustang is a bad idea. All you have accomplished is to make the computer mad and spit codes. The pollution control equipment all shuts off at wide open throttle, so the HP losses from it on the car are 2-5 HP. The catalytic converters may soak a few more HP than that. None of the pollution control equipment reduces the HP enough to cost you a race in anything but professional drag strip competition. I seriously doubt that you will be in the final runoff on “Pinks”, so leave the smog equipment in place and make sure it is working correctly.

    Know what does what before removing it. Remove or disable the wrong thing and the computer sets the check engine light and runs in "limp mode". Limp mode means reduced power and fuel economy.

    If you removed the smog pump and still have catalytic converters, they will ultimately clog and fail.

    Here's a book that will get you started with how the Ford electronic engine control or "computer" works.

    Ford Fuel Injection & Electronic Engine Control 1988-1993 by James Probst :ISBN 0-8376-0301-3.

    It's about $20-$45 from Borders.com see http://www.amazon.com/ . Select books and then select search. Use the ISBN number (without dashes or spaces) to do a search

    Use the ISBN number and your local library can get you a loaner copy for free. Only thing is you are limited to keeping the book for two weeks. It is very good, and I found it to be very helpful.

    Remove any of the equipment and you will not pass a full smog check, cannot title the car in an area that does smog checks and have broken several federal laws. Granted that the Feds are short on people to check cars, but it is still Federal law.

    "Why should I leave the smog equipment on if I live in an area that doesn't do smog inspections?"
    What's good sauce for the goose is good sauce for the gander. I lived in Florida and had two smog pumps fail on two different 89 5.0 Mustangs. I replaced both of them, even though there was no emissions inspection. Why?

    1.) It a federal law that requires emissions equipment to be in place and functional. I have no intention of breaking a law designed to protect my general health and wellbeing, even if I don't like it. I have respect for the rights and wellbeing of other people, and am not one of those whose nature is rebellion.

    2.) Whatever imaginary "improvements" someone may strive for, there is very little evidence that the results of removing emissions results in a better car. I can achieve excellent results in performance with all the smog equipment in place and working properly. Maybe you can't, but that is no excuse for removing the emissions equipment. Look at the new 5.0 Mustangs – 281 cubic inches and 400+ flywheel HP with full emissions equipment with no aftermarket parts. That tells me that it is possible on a mass production car. It also shows that the guys that designed the engine knew what they were doing to achieve that goal.

    3.) I like to breathe clean air, and working emissions equipment helps me do my part to make that possible. Los Angeles has breathable air even with millions of cars: Beijing, the capitol of China has some of the worst air in the world. Why – no emissions requirements for cars.

    I don’t want to live where the air looks like this…
    [​IMG]
    See http://www.taipeitimes.com/News/feat/archives/2014/01/15/2003581312
    #3
  4. 1992MustangGT

    1992MustangGT Member

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    Well it sounds like it will cause more problems by removing it than it will benefit. If removing it will cause driveablity and computer issues (in addition to clogging the cats), then I would rather not do this. I'm not racing it at the track, so the WOT scenario or racing on Pinks isn't an issue. Thank you for the reference of the book. I will definitely look into it and educate myself on the smog system....Maybe it would be easier and less headache in the long run to just buy a new smog pump. Hmm......

    Thanks for the advice guys...
    #4
  5. jcgafford

    jcgafford Well-Known Member

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    There is not much to the smog pumps. Pull it off and open it up. You may be able to fix it. I fixed mine this way
    #5
  6. 2000xp8

    2000xp8 Mustang Master

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    Me personally i take no issue with removing smog parts. I've ran my car that way for 20 years, never any issues with driveability. (not saying it's right or wrong and back in the day there were almost no choices for catted pipes other than stock)
    But you have to be prepared to buy an offroad x or h pipe.
    Last edited: Jan 24, 2014
    #6
  7. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    smog pump, what's that? :shrug:
    #7
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  8. mikestang63

    mikestang63 Mustang Master

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    You will get both pro and against views for removing smog equipment. I have removed it from every Mustang I've owned, except for my wife's 2013. I live in a state with no smog check. so that does make a huge difference in choice.

    If you do remove your smog pump and thermactor hoses, you need to either gut or replace the stock catted mid pipe as the material in the cats will fuse together. Most people replace it with an off road H pipe.

    Know that some people complain of excessive exhaust smell afterwards.
    #8
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  9. Mustang5L5

    Mustang5L5 Car used in adult film "Highway Gangbang-InDaButt" SN Certified Technician Founding Member

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    I feel like we just had this thread….didn;t we?
    #9
    jcgafford likes this.
  10. mikestang63

    mikestang63 Mustang Master

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    Once a week it comes up I'd say.
    #10
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  11. Kumm3

    Kumm3 Founding Member

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    I still run mine, but it just pumps fresh air into my cats. I cannot run a full EGR system as i have an EFI Victor Jr intake and there are no EGR ports to speak of.

    So i just have the port open on the back of the vacuum valve. Haven't had a problem yet.
    #11
  12. santos

    santos Founding Member

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    what is all this smog stuff? what are "cats"?
    #12
  13. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Catalytic Converters

    Here's a dump on how much of the emissions control equipment works...

    Thermactor Air System
    Some review of how it works...

    Revised 17-Sept-2011 to add testing procedure.

    The Thermactor air pump (smog pump) supplies air to the heads or catalytic converters. This air helps break down the excess HC (hydrocarbons) and CO (carbon monoxide). The air supplied to the catalytic converters helps create the catalytic reaction that changes the HC & CO into CO2 and water vapor. Catalytic converters on 5.0 Mustangs are designed to use the extra air provided by the smog pump. Without the extra air, the catalytic converters will clog and fail.

    The Thermactor air pump draws air from an inlet filter in the front of the pump. The smog pump puts air into the heads when the engine is cold and then into the catalytic converters when it is warm. The Thermactor control valves serve to direct the flow. The first valve, TAB (Thermactor Air Bypass) or AM1 valve) either dumps air to the atmosphere or passes it on to the second valve. The second valve, TAD (Thermactor Air Diverter valve or AM2 valve) directs it to the heads or the catalytic converters. Check valves located after the TAB & TAD solenoids prevent hot exhaust gases from damaging the control valves or pump in case of a backfire. The air serves to help consume any unburned hydrocarbons by supplying extra oxygen to the catalytic process. The computer tells the Thermactor Air System to open the Bypass valve at WOT (wide open throttle) minimizing engine drag. This dumps the pump's output to the atmosphere, and reduces the parasitic drag caused by the smog pump to about 2-4 HP at WOT. The Bypass valve also opens during deceleration to reduce or prevent backfires.

    Code 44 RH side air not functioning.
    Code 94 LH side air not functioning.

    The computer uses the change in the O2 sensor readings to detect operation of the Thermactor control valves. When the dump valve opens, it reduces the O2 readings in the exhaust system. Then it closes the dump valve and the O2 readings increase. By toggling the dump valve (TAB), the computer tests for the 44/94 codes.

    Failure mode is usually due to a clogged air crossover tube, where one or both sides of the tube clog with carbon. The air crossover tube mounts on the back of the cylinder heads and supplies air to each of the Thermactor air passages cast into the cylinder heads. When the heads do not get the proper air delivery, they set codes 44 & 94, depending on which passage is clogged. It is possible to get both 44 & 94, which would suggest that the air pump or control valves are not working correctly, or the crossover tube is full of carbon or missing.


    [​IMG]


    Computer operation & control for the Thermactor Air System
    Automobile computers use current sink technology. They do not source power to any relay, solenoid or actuator like the IAC, fuel pump relay, or fuel injectors. Instead the computer provides a ground path for the positive battery voltage to get back to the battery negative terminal. That flow of power from positive to negative is what provides the energy to make the IAC, fuel pump relay, or fuel injectors work. No ground provided by the computer, then the actuators and relays don't operate.

    One side of the any relay/actuator/solenoid in the engine compartment will be connected to a red wire that has 12-14 volts anytime the ignition switch is in the run position. The other side will have 12-14 volts when the relay/actuator/solenoid isn't turned on. Once the computer turns on the clamp side, the voltage on the computer side of the wire will drop down to 1 volt or less.

    In order to test the TAD/TAB solenoids, you need to ground the white/red wire on the TAB solenoid or the light green/black wire on the TAD solenoid.

    For 94-95 cars: the colors are different. The White/Red wire (TAB control) is White/Orange (Pin 31 on the PCM). The Green/Black wire (TAD control) should be Brown (pin 34 at the PCM). Thanks to HISSIN50 for this tip.

    Testing the system:

    To test the computer, you can use a test light across the TAB or TAD 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.

    Disconnect the big hose from smog pump: with the engine running you should feel air output. Reconnect the smog pump hose & apply vacuum to the first vacuum controlled valve: Its purpose is to either dump the pump's output to the atmosphere or pass it to the next valve.

    The next vacuum controlled valve directs the air to either the cylinder heads when the engine is cold or to the catalytic converter when the engine is warm. Disconnect the big hoses from the back side of the vacuum controlled valve and start the engine. Apply vacuum to the valve and see if the airflow changes from one hose to the next.

    The two electrical controlled vacuum valves mounted on the rear of the passenger side wheel well turn the vacuum on & off under computer control. Check to see that both valves have +12 volts on the red wire. Then ground the white/red wire and the first solenoid should open and pass vacuum. Do the same thing to the light green/black wire on the second solenoid and it should open and pass vacuum.

    Remember that the computer does not source power for any actuator or relay, 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.

    The computer provides the ground to complete the circuit to power the solenoid valve that turns the
    vacuum on or off. The computer is located under the passenger side kick panel. Remove the kick panel & the cover over the computer wiring connector pins. Check Pin 38 Solenoid valve #1 that provides vacuum to the first Thermactor control valve for a switch from 12-14 volts to 1 volt or less. Do the same with pin 32 solenoid valve #2 that provides vacuum to the second Thermactor control valve. Starting the engine with the computer jumpered to self test mode will cause all the actuators to toggle on and off. If after doing this and you see no switching of the voltage on and off, you can start testing the wiring for shorts to ground and broken wiring. An Ohm check to ground with the computer connector disconnected & the solenoid valves disconnected should show open circuit between the pin 32 and ground and again on pin 38 and ground. In like manner, there should be less than 1 ohm between pin 32 and solenoid valve #2 and pin 38 & Solenoid valve #1.

    If after checking the resistance of the wiring & you are sure that there are no wiring faults, start looking at the solenoid valves. If you disconnect them, you can jumper power & ground to them to verify operation. Power & ground supplied should turn on the vacuum flow, remove either one and the vacuum should stop flowing.

    Typical resistance of the solenoid valves is in the range of 20-70 Ohms.

    Theory of operation:
    Catalytic converters consist of two different types of catalysts: Reduction and Oxidation.
    The Reduction catalyst is the first converter in a 5.0 Mustang, and the Oxidation converter is the second converter. The Oxidation converter uses the extra air from the smog pump to burn the excess HC. Aftermarket converters that use the smog pump often combine both types of catalysts in one housing. Since all catalytic reactions depend on heat to happen, catalytic converters do not work as efficiently with long tube headers. The extra length of the long tubes reduces the heat available to operate the O2 sensors and the catalytic converters. That will cause emissions problems, and reduce the chances of passing an actual smog test.


    Now for the Chemistry...
    "The reduction catalyst is the first stage of the catalytic converter. It uses platinum and rhodium to help reduce the NOx emissions. When an NO or NO2 molecule contacts the catalyst, the catalyst rips the nitrogen atom out of the molecule and holds on to it, freeing the oxygen in the form of O2. The nitrogen atoms bond with other nitrogen atoms that are also stuck to the catalyst, forming N2. For example:

    2NO => N2 + O2 or 2NO2 => N2 + 2O2

    The oxidation catalyst is the second stage of the catalytic converter. It reduces the unburned hydrocarbons and carbon monoxide by burning (oxidizing) them over a platinum and palladium catalyst. This catalyst aids the reaction of the CO and hydrocarbons with the remaining oxygen in the exhaust gas. For example:

    2CO + O2 => 2CO2

    There are two main types of structures used in catalytic converters -- honeycomb and ceramic beads. Most cars today use a honeycomb structure." Quote courtesy of How Stuff Works (HowStuffWorks "Catalysts")

    What happens when there is no extra air from the smog pump...
    As engines age, the quality of tune decreases and wear causes them to burn oil. We have all seem cars that go down the road puffing blue or black smoke from the tailpipe. Oil consumption and poor tune increase the amount of HC the oxidation catalyst has to deal with. The excess HC that the converters cannot oxidize due to lack of extra air becomes a crusty coating inside the honeycomb structure. This effectively reduces the size of the honeycomb passageways and builds up thicker over time and mileage. Continuous usage under such conditions will cause the converter to fail and clog. The extra air provided by the Thermactor Air System (smog pump) is essential for the oxidation process. It oxidizes the added HC from oil consumption and poor tune and keeps the HC levels within acceptable limits.

    Newer catalytic converters do not use the Thermactor Air System (smog pump) because they are designed to work with an improved computer system that runs leaner and cleaner
    They add an extra set of O2 sensors after the catalytic converters to monitor the oxygen and HC levels. Using this additional information, the improved computer system adjusts the air/fuel mixture for cleaner combustion and reduced emissions. If the computer cannot compensate for the added load of emissions due to wear and poor tune, the catalytic converters will eventually fail and clog. The periodic checks (smog inspections) are supposed to help owners keep track of problems and get them repaired. Use them on an 86-95 Mustang and you will slowly kill them with the pollutants that they are not designed to deal with.



    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.

    [​IMG]

    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)
    [​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. 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
    [​IMG]

    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.
    #13
  14. santos

    santos Founding Member

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    im almost sorry i asked lol
    #14
  15. mikestang63

    mikestang63 Mustang Master

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    Yeah. Jrichker is a wealth of knowledge. Be prepared for a thoroughly detailed answer. In the future just know when you ask, be prepared for

    RELEASE THE JRICHKER! lol

    [​IMG]
    #15
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  16. santos

    santos Founding Member

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    well, i DO know what "cats" are, i was only being sarcastic
    #16
  17. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Unfortunately, it is difficult to communicate sarcasm when writing short sentences... :rolleyes:
    #17
  18. santos

    santos Founding Member

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    I Agree, but i do appreciate the info, very informative. <---- NOT sarcasm lol
    #18
  19. madspeed

    madspeed Colonel Mustard Mod Dude Founding Member

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    There can only be one bunghole in the bunch
    #19
  20. santos

    santos Founding Member

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    hey, someone has to do it!
    #20

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