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Thread: 1986 Cougar 3.8 L won't idle.

  1. #11
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    The backbone of the diagnostic process it SSCC, or Symptom, System, Component, Cause.
    Symptom - crank/no-start
    System - fuel system. When alternate fuel is introduced, the symptom is temporarily resolved
    Component - ?
    Cause - ?

    This is where you are in the process. Here are the questions to ask: what are the components in the fuel delivery system?, which ones are working?
    Your other posts, talk about fuel pressure. You have roughly 40 psi? if that's the case, you can rule out the pump, it's wiring, and it's command, as well as the lines. You have a new regulator, so lets assume it's good. That leaves injectors (2) and wiring. Test: with key on, the injectors should have power, but not ground. Disconnect the injector connectors and check for power with a multi-meter. If you don't have one, a test light will do for now. If there's power, you'll want to see if the EEC is pulsing them on (by grounding them). To do that, you'll want to get what's called a "noid" light. If you plug in the noid light to the injector connector, and it flashes while you're cranking the engine (on both) your injectors are being fired. Are they actually spraying fuel? If yes, something got missed, if no, you have Component
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  2. #12
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    Thanks for the suggestion! I think the mechanic already tried this test but I will pass this on to him - I am heading over there now. I miss my car!

  3. #13
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    Quote Originally Posted by TheFoeYouKnow View Post
    The backbone of the diagnostic process it SSCC, or Symptom, System, Component, Cause.
    Symptom - crank/no-start
    System - fuel system. When alternate fuel is introduced, the symptom is temporarily resolved
    Component - ?
    Cause - ?
    This is where you are in the process. Here are the questions to ask: what are the components in the fuel delivery system?, which ones are working?
    Your other posts, talk about fuel pressure. You have roughly 40 psi? if that's the case, you can rule out the pump, it's wiring, and it's command, as well as the lines. You have a new regulator, so lets assume it's good. That leaves injectors (2) and wiring. Test: with key on, the injectors should have power, but not ground. Disconnect the injector connectors and check for power with a multi-meter. If you don't have one, a test light will do for now. If there's power, you'll want to see if the EEC is pulsing them on (by grounding them). To do that, you'll want to get what's called a "noid" light. If you plug in the noid light to the injector connector, and it flashes while you're cranking the engine (on both) your injectors are being fired. Are they actually spraying fuel? If yes, something got missed, if no, you have Component
    The mechanic has done the noir test and the injectors are firing as they normally should. However, they aren't getting any fuel. When starter fluid is sprayed into the TBI the car starts right up and the only way to keep it running is my pressing the gas pedal repeatedly. The car isn't drivable currently. My mechanic had a question: How does this car normally at start up get fuel to the injectors?

  4. #14
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    You have fuel pressure? Roughly 40 psi? Can fuel be seen spraying when the engine is cranking?
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

    88 Thunderbird/Cougar EVTM
    (Thanks to Trinom for hosting)

  5. #15
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    Quote Originally Posted by TheFoeYouKnow View Post
    You have fuel pressure? Roughly 40 psi? Can fuel be seen spraying when the engine is cranking?
    I do know the fuel pressure is good. The psi is 35 or more which according to the shop manual is correct for a 1986 model. I will check with the mechanic to see if fuel is spraying when the engine is cranking. I don't think it is because if it was wouldn't the car start? The only way this car starts now is when starter fluid (or carb. cleaner) is sprayed directly into the TDI.

  6. #16
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    Quote Originally Posted by midnight cat View Post
    I do know the fuel pressure is good. The psi is 35 or more which according to the shop manual is correct for a 1986 model. I will check with the mechanic to see if fuel is spraying when the engine is cranking. I don't think it is because if it was wouldn't the car start? The only way this car starts now is when starter fluid (or carb. cleaner) is sprayed directly into the TDI.
    If fuel can be seen spraying while cranking the engine what does that indicate? Does that mean it's not getting enough fuel and that's why it needs alternate fuel as well to start?

  7. #17
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    Per your previous post, the car runs just fine with the exception that it won't idle without your foot on the gas pedal?

  8. #18
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    Quote Originally Posted by JeremyB View Post
    Per your previous post, the car runs just fine with the exception that it won't idle without your foot on the gas pedal?
    Correct.

  9. #19
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    Quote Originally Posted by JeremyB View Post
    Highly doubtful. TPS or ISC are my first thoughts, but get the KOEO and KOER codes to give you some better direction.
    Quote Originally Posted by JeremyB View Post
    I had to look it up myself to make sure I wasn't forgetting things. Getting old!

    ISC = Idle Speed Control. CFI's method to control idle. It physically moves the throttle blade to adjust airflow. IAC sends air through it and bypasses the throttle blades.


    This...

    You didn't indicate what the actual code that was thrown... Have you verified voltage at idle?


    Although the 3.8 likes to blow head gaskets, the earlier ones aren't nearly as bad as the latter. Mine made it 226k before blowing.
    Still my first thought. No offense, but not sure your mechanics have the background to solve the problem without just throwing parts at it.

  10. #20
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    Quote Originally Posted by JeremyB View Post
    ISC = Idle Speed Control. CFI's method to control idle. It physically moves the throttle blade to adjust airflow. IAC sends air through it and bypasses the throttle blades.
    I'm thinking if this were the case though it would be causing a deficiency in air delivery, not fuel delivery right? Spraying alternative fuel should have no effect if its a case of not enough air making it through the TV
    --Steve
    1988 Cougar V6
    2012 F-150 3.7L
    2011 Mustang 3.7L

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