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  1. #1

    Default 1986 GT EGR Solenoid Valve Operation & Testing

    I have a 1986 GT Automatic on which I'm working on the EGR system. It sets a Code 31 for the EGR sensor so I'm in the process of taking everything apart to clean and test. Everything is fairly clean as the car has only a little over 100,000 KM (about 60,000 miles) and runs really well except for the Code 31 and a backfire when I let off quickly at the end of the quarter mile on a dragstrip run. If I let off slowly no problems.

    The car has a really poor aftermarket exhaust that looks like it was made at a muffler shop with cheap Thrush 17658 mufflers and tailpipes with Magnaflow tips. It is loud. The pipes appear to be 2.25" throughout. No cats and no H crossover. Just straight pipes back from each side. The smog pump is connected via the original pipe to the approximate location of the original in just the passenger side exhaust pipe. The O2 sensors are very close to the stock header output and look pretty close to the stock location.

    I have a number of questions regarding the operation and testing of the EGR system.

    1. Is the EGR valve a back pressure type (negative or positive back pressure) that will not operate properly with this type of exhaust system? Does it need some back pressure? I'm interested in any comments from those that have had problems with Code 31 and aftermarket exhaust with no cats with or without the convertor air pipe operational.

    2. Has anyone had any experience with bench testing the EGR solenoid (E53E-9J459-AA) that controls the EGR valve? I've tried to test the solenoid and I'm not sure I'm doing it properly. Pictures of the valve are enclosed below. When I connect 12 volt supply to the two contacts there is no audible click like the thermactor TAB and TAD solenoids. Should there be?

    3. When I connect a vacuum pump to the supply port on the valve (bottom side) and a vacuum guage to the output port (top side) and 12 volts to the contacts and then try to pump vacuum through the valve the valve will not pump up and hold vacuum. However, as the vacuum drops it seems to slow down at around 5-6 In and then drop slowly from there. The valve will not hold vacuum at all without 12 volts across the contacts and drops quickly to zero rather than stalling at 6 In. I went out to the autowreckers and picked up three spare valves of the same number and vintage (Tempo and Topaz of late 1980s seem to have them). They all seem to have about 45 ohms resistance across the contacts. I believe this indicates the solenoid coil is okay. One of the valves from the wreckers will hold vaccum at 6 In. when powered by 12 volts. When the 12 volts is disconnected the valve makes an audible sound and releases the vacuum through the port at the very top of the valve under the cap through the filter. The valves that do not hold vaccum at 6 In. will also will release vacuum quickly with sound when the 12 volt supply is disconnected. There are actually three ports in this valve, bottom supply on the side, top side output to the EGR and top output to atmosphere through the filter under the cap. All are about the same size. It appears this valve does more than just apply and release vacuum to the EGR valve. It looks like it also regulates max vacuum to the EGR at about 6 In.

    a) Am I testing this valve correctly,

    b) does this valve regulate vacuum to the EGR at about 6 In.,

    c) is it supposed to hold vacuum or not and which valve (holding vacuum or not) is operating properly, or

    d) are they all defective or all okay?

    The backfire is another issue I'm working on. I'm in the process of cleaning and testing all the parts for this but have not gotten very far yet other then dropping the solenoid valve on the floor and breaking the lower supply port off one of the valves. Expensive, but luckily I was able to locate one on eBay and it is on its way. Once I get it I'll test that system.

    Hope this all makes sense.
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  2. #2
    FEP Super Member xctasy's Avatar
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    Jun 2012
    Dunedin 9011, New Zealand, South Pacific


    See mrriggs post.

    Read the specs I suplied. #10

    His car is an 84 4BBL 5.0 , but it has some CFi 5.0 parts mixed in.

    All EGR valves run on Pulse Width Modulation, with a duty cylce, and a swing from hight to low voltage, with battery voltage at peak, 13 to sometimes 14.2 volts. Like ISC's or Mixture Control Solenoids on Feedback carbs, the PWM/Duty Cycle and upper and lower voltage swings are how the valve is controlled. The pressure readings are the result of the gate valve swinging backwards and forwards as its modulated by the EECIV.

    Many Escort, Tempo parts swap over, the EFI TAB/TAD is EECIV contolled, and and any other EECIV system that physically fits and has the same Pulse Width Modulated control can be spliced in. They key is understanding how it serves the 5.0 Port EFI, its similar to the twin point 84 to 85 auto only HO CFi 5.0, but not the same, as the CFi was a hybridised EECIII 5.0, and that system was more 2-bbl Carb based, with a little less catalyst.

    Your 86 has four catalysts for a reason....its an early, high compression car with high swirl heads, so it made a lot more hydrocarbons than the ealier 5.0 4bbl carb engines, and wasn't as economical. So the EGR had to programed differently. It gave Ford some freedom to unbottle the engine with 9:1 compession, instead of 8.4:1.

  3. #3


    Thanks for the input. I'm going out of town for a few days so I'll try and absorb and research. I'm sure I'll have some more questions.

  4. #4
    FEP Super Member xctasy's Avatar
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    Jun 2012
    Dunedin 9011, New Zealand, South Pacific


    Name it and claim it time.

    Haystack found what I did, no common 1986 GT Emmission/ Vacuum Lines diagram.

    Quote Originally Posted by Haystack View Post

    Should go to the tab/tad stuff. My guess is that if the vacuum lines are missing, so is the rest.

    1, 2, 14, 18, 20. 41, 43, 49, 50, 51, 52 and 53 are the critical EGR related parts.

    1. Thermactor Air Diverter Solenoid (TAD) - Directs thermactor air from the rear of the cylinder heads to the exhaust H pipe after warm up
    2. Thermactor Air Bypass Solenoid (TAB) - Vents thermactor air during periods when it is not needed (primarily cold starts)
    3. Vacuum Storage Canister - Stores Vacuum to prevent interruption of services during wide open throttle
    4. Throttle Body - Regulates the amount of air entering the engine
    5. Air Inlet Hose - Directs air into the throttle body from the mass air meter (Mass air car) or the air box (Speed Density Car)
    6. Idle Air Bypass Valve - Regulates the amount of air needed to maintain a smooth idle
    7. Engine Coolant Temperature Sensor (ECT) - Reports the coolant temp to the computer
    8. Injectors - delivers fuel sequentially to each cylinder
    9. Oil Filler Cap
    10. WOT Cutout Relay - Kills AC compressor during wide open throttle
    11. Fuel Pump relay - The computer activates the fuel pump through this relay
    12. Mass Air Flow Sensor - The Electronic device used to measure the amount of air passing through the meter
    13. Mass Air Flow Meter - Electrically measures the amount of air entering the engine and reports the information back to the computer
    14. Thermactor Bypass Valve - Directs the flow of air supplied by the thermactor (fresh air) pump
    15. Alternator
    16. Belt Tensioner
    17. Air Silencer - Used to muffle incoming air noise (located in the fender)
    18. Canister Purge Solenoid - Allows fuel vapors from the carbon canister to enter the intake manifold
    19. Air Cleaner Housing - Contains the air filter
    20. Thermactor Air Pump - Delivers high volume, low pressure fresh air to the exhaust system
    21. Water Pump, Fan, and Fan Clutch
    22. Air Conditioner Condenser Connections - Attaches refrigerant lines to air conditioning condenser
    23. Center Line Crash Sensor - 90-93 only - triggers air bag in the event of a front end collision
    24. Radiator
    25. Radiator Cap
    26. Coolant Reservoir and Low Coolant Switch (if so equipped)
    27. Power Steering Pump
    28. Battery
    29. Air Conditioning Compressor
    30. Spout Check Connector - Must be unplugged when checking initial ignition timing
    31. Windshield Washer Reservoir
    32. Vacuum Hose Diagram
    33. Ignition Coil - under plastic cover
    34. Starter Relay - under plastic cover
    35. Coolant Temperature Sender - Relates coolant temperature to the gauge in the instrument panel
    36. Engine Oil Dipstick
    37. Electronic Distributor - Controlled by the computer
    38. Front Strut Insulator and Camber Adjustment Plate
    39. Upper Intake Plenum
    40. Brake Master Cylinder and Booster
    41. VIP Test Connectors - computer test ports
    42. Windshield Wiper Motor
    43. Vacuum Distribution Tee - From left to right the connections are: vacuum source (intake manifold), unused, vacuum reservoir, speed control servo (if equipped with cruise), power brake booster
    44. Air Charge Temperature Sensor - Reports the temperature of the air in the intake manifold to the computer
    45. Barometric Absolute Pressure Sensor (BAP) - Reports barometric air pressure to the computer
    46. Positive Crankcase Ventilation Valve (PCV Valve) - relieves crankcase pressure
    47. Fuel Pressure Regulator - Uses intake manifold vacuum to lower the fuel rail pressure during low rpm operation
    48. 10-pin connector - Mates the engine wiring harness with the main wiring harness and the EEC computer
    49. EGR Vacuum Regulator Solenoid - Controls the vacuum which opens the EGR valve
    50. EGR Valve and EGR Position Sensor - Allows exhaust gases to enter the intake passage during various engine speeds. Reports valve position to computer
    51. EGR Spacer - Provides a hot gas passage to and from the EGR valve
    52. EGR Coolant Hoses - Circulates coolant through the EGR spacer
    53. Throttle Position Sensor - Relates the percentage of throttle opening to the computer
    54. Transmission Dipstick Tube - Auto trans only
    55. Crankcase Ventilation Tube - Allows crankcase fumes to enter the intake system
    56. Wiring Harness - Cable system that connects all of the engine's electrical components to the computer in the passenger side kick panel
    57. AC Accumulator - Provides a storage area for the refrigerant in the AC system and houses a chemical drier that removes moisture from the refrigerant
    58. Vacuum Check Valve - Allows air to flow in only one direction in order to keep vacuum storage canister fully charged
    59. Hood Ground Strap
    60. AC Low Pressure Switch - Will not allow the air conditioner compressor clutch to energize if refrigerant pressure drops to an unsafe limit

    The EGR Vacuum Control solenoid & EGR Vent valve solenoid works on a warm engine. You pull the vacuum line off the EGR and hold your finger over the line while you rev the engine. You should feel vacuum on the EGR line when you rev it, and then it should go away at idle. The EGR Vacuum Control solenoid lets the vacuum through, and the EGR Vent valve solenoid releasing the vacuum.

    The computer activates the EGR Vacuum Control solenoid, and then it looks at the EGR sensor via its voltage to see how much it opened.

    It does this under Pulse Width Modulation, back and forth, modulating the the amount of inert EGR gas to the engine.

    The four element Secondary AIR system is separate, but nothing works in isolation.

    * raided from

    The 86 upper intake has unique porting

    The 86 PCV long hose that does a 180 degree loop

  5. #5


    Thanks again for the input. I've just gotten back to working on the car the last few days after being busy with other things and waiting for some new parts. Hopefully I'll be able to provide a complete report on what I've found and done.

    Quick question. Where is the PCV in the photo of the underside of the 1986 upper intake?

  6. #6
    FEP Super Member xctasy's Avatar
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    Jun 2012
    Dunedin 9011, New Zealand, South Pacific


    None on the net. PB picture drop offs mean you won't find one fast.

    Its the unanswered question. You need a mirror and a special set of long nose pliers.

    I'm a kid borne of whisky and of the drung infested late 60's, brought up on a diet of simple GM in line and Mopar slant sixes. Service tool, no way....

    Its what hacks me off about all modern EFI vehicles....but be glad, Toyotas are far worse.
    Quote Originally Posted by Rayo
    No need to remove all that..

    I would suggest getting a pair of these:

    10 Long Reach Bent Nose 90 Pliers

    When I pulled the PCV Element(Screen) on my buddys Sport...The only way I could reach it was with a pair of these style pliers..

    I had to fight with it a little bit because it was so gummed up..but...I won!..

    Quote Originally Posted by Syco Stang View Post
    ....... Disconnect the vacuum lines going to the PCV valve in the lower intake, remove the vacuum line at the fuel pressure regulator (red) and remove the vacuum line for the MAP sensor. Remove the 6 bolts and 1 nut holding it place and lift up, usually they come off pretty easy.

    That being said, you shouldn't have to remove your upper intake to get to the connection spot for the MAP sensor, I'll try and get a picture of the vacuum "tree" that comes off of the upper intake and goes to varying places. The inlet for the MAP is right beside the big hose for the vacuum tree at the back of the manifold. I think it's a 1/4" line. If your hands are really that Ogreish, then you would probably benefit from removing the upper intake, it's going to be kinda hard to get the PCV hose back on in the very back of the lower intake when you're putting it back on but it'll still be pretty easy, even if you've got AC. Hope this helps.

  7. #7
    FEP Super Member xctasy's Avatar
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    Jun 2012
    Dunedin 9011, New Zealand, South Pacific


    You have to use the CJpony Breakout list
    1, 2, 14, 18, 20. 41, 43, 49, 50, 51, 52 and 53 are the critical EGR related parts.
    43, 49 are what you need to find on the diagram below. IIRC, The blue line loops under the intake upper manifold in a quirky manner.

  8. #8

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