Electrical 93 Lx 5.0 Timing Advance Issues Need Help Bad

Discussion in 'Fox 5.0 Mustang Tech' started by missin'5.0, Aug 30, 2013.


  1. missin'5.0

    missin'5.0 New Member

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    Ok guys new to the site, all and any help would be great.

    So the story goes pulled out driveway 1st,2nd, clutch for 3rd car stalls. No spark, I install a new icm tfi module car fires up but rough as all get out. Get her into my garage check several things and see no obvious issues. So I get 2 more new icm tfi modules and get the same outcome. Since I have found no vac leaks and have 18 hg vac at idle. New tps,new mass air, new comp, new dizzy, new plugs gapped. 52,new wires,new coil, new walbro 190lph pump new filter. Visual on fpr checks out as I see or smell no fuel. Fuel pressure is 32 vac on 40 vac off. I have new pcv kit with screen grommet and pcv it self. Timing is base set at 12 btdc. And positive its not 180 off. I have solid continuity from eec plug to tfi mudule through spout wire. 3rd wire down on tfi plug has 12v while cranking, and 2.7volts while running, ive heard it should only have voltage when crancking as so keep timing in line for startup......?? All my work has shown to not help... car will idle though a touch rough, when it is revved up the timing does not advance as it should,it actually retards several degrees to around 0 tdc blows black smoke rich and burns eyes. Car is stock with flowmaster 40s no cats or smog and shorty headers.
    #1
  2. mikestang63

    mikestang63 Mustang Master

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    spout in?
    aftermarkert TFI's are garbage. Buy a FOMOCO. Did you clean off the old grease and apply new grease to the backside?
    What distributor brand? MSD maybe?
    Seems like you installed a lot of new parts. What MAF.

    Have you run the koeo and koer codes?
    #2
  3. missin'5.0

    missin'5.0 New Member

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    I noticed last night that with the clutch pressed the 2.7volts is off of tfi 3rd pin and car will rev and advance timing as it should, let off pedal and its back to running rough with 2.7 volts on tfi 3rd pin. So I clipped the white w/pink tracer wire off ignition switch after I started car, 2.7 remains on the wire but not on ignition side. Then I noticed if I pull red w/blue tracer wire from ignition solenoid and push clutch in it has 2.7 volts on it as well, pop it back on stud and 2.7 is gone and it shows 0.... then with car running still I clipped 3rd pin at tfi 6 inches back while it had 2.7 volts on it and the car will advance timing. The 3rd wire then shows 0 volts tfi side and 4.5 volts back towards firewall??? What the heck.... so I get in car and check the white w/pink trace ignition side still 0 other side 4.5 volts..... im at wits end especially since im an electrician lol. Im super lost and miss my car, been down 2 months. Please help!
    #3
  4. missin'5.0

    missin'5.0 New Member

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    Spout in, 4 different tfi modules, new thermo compound to backside of all the tfi I tried. Motorcraft dizzy, reman oem mass air. No codes either way...just 11
    #4
  5. missin'5.0

    missin'5.0 New Member

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    A friend also verified on his fox that when cranking 12v is needed on pin 3 red w/blue trace. It falls to 0 volts after car starts, his runs great.
    #5
  6. missin'5.0

    missin'5.0 New Member

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  7. vfast

    vfast Member

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    what does the egr valve look like inside?
    #7
  8. missin'5.0

    missin'5.0 New Member

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    Egr is bypassed, smog pump as well. Traced the circuit all the way to pin 30 on the EEC, I've put a brand new one in and it didn't change anything.
    #8
  9. missin'5.0

    missin'5.0 New Member

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    I can't find any solid reason for voltage to be on pin 3 of the TFI for any reason other than while starting and that is 12v.
    #9
  10. mikestang63

    mikestang63 Mustang Master

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    do you have some mismatched or swapped harnesses?
    #10
  11. missin'5.0

    missin'5.0 New Member

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    Car is an original auto, that I swapped to a 5 speed, I used all oem wiring theres nothing to it
    #11
  12. missin'5.0

    missin'5.0 New Member

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    Have driven the car 4 years since swap no issues what so ever
    #12
  13. LarsD

    LarsD Founding Member

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    I had a very similar issue that turned out to be a red-top with an intermittent cell. Doesn't sound like your problem though. Pull your ignition switch and see what it looks like. These cars start to do all kinds of screwy stuff when that switch goes bad. I had to replace mine a few weeks ago because my blinkers on the dash got intermittent, and it would die while coasting if I bumped the key.
    #13
  14. missin'5.0

    missin'5.0 New Member

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    Ok cool, battery I have not checked, ignition switch is new though..I got a ghost im chasing here guys very frustrating
    #14
  15. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Make sure that the car does not start in gear. There are some differences with the O2 sensor/neutral safety circuit wiring harness between 5 speed and automatic transmission.

    Diagram courtesy of Tmoss & Stang&2birds

    [​IMG]

    O2 Sensor harness interchange and modification

    Originally Posted by 302EFI


    Revised 16-Oct-2011 to add O2 sensor harness warnings
    The wires for the 02's and low oil did not change throughout the years, they are all in the same place.
    The main ones you need to worry about are (on the harness end (ECU) that plugs into the 02 plug) is:
    \- 1. Lightblue / yellow
    - 2. White / Purple
    - 3. Purple / Yellow
    The White/Purple & Purple/Yellow gets looped for a automatic ECU
    The Purple/Yellow & Lightblue/Yellow for a manual ECU

    See http://forums.corral.net/forums/gen...manual-auto-differences-year-differences.html for more O2 sensor wiring harness info

    Basic premise to use with transmission swaps:
    Only run a 5 speed trans O2 harness with an A9L. Do not run an Auto O2 sensor harness with an A9L. Doing so will damage the computer’s internal signal ground.
    Only run an Auto trans O2 sensor harness with an A9P in a car that has an Auto trans. Using a 5 speed trans O2 sensor harness with an Auto trans will cause no crank problems.
    See http://www.stangnet.com/mustang-forums/749974-computer-issue.html#post7490537 for Joel5.0’s fix to the computer internal signal ground.

    90 model year harness only works with 90 model cars without inspection/rework.
    The 4 cylinder O2 harness uses 4 wire O2 sensors. It probably won’t work correctly without modifying it.

    Recall on Ford Ignition switches:
    Some of the symptoms of ignition switch problems are things that don’t work or are intermittent like radio, turn signals, wipers or heater.

    There was a FREE recall on Ford ignition switches. They overheat and sometimes catch fire. That burns up the steering column and sometimes the car interior. Since this is very old information, you may not be able to get the switch replaced for free anymore. The auto parts stores sell the switches for $13-$15.

    [​IMG]

    [​IMG]

    [​IMG]

    Saleen0679 was nice enough to dig this up for us awhile back: Replace a 1979-1993 Ignition Switch Assembly


    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.

    Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
    http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.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

    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


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

    HVAC vacuum diagram
    http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

    TFI module differences & pin out
    http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

    Fuse box layout
    http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

    87-92 power window wiring
    http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

    93 power window wiring
    http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif
    #15
  16. missin'5.0

    missin'5.0 New Member

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    I have a new ignition switch, from ignition switch the white pink trace wire runs to driver kick panel to a plug, at that plug a white with purple trace wire is factory crimped inside the plug with the white pink trace wire the white purple trace goes though firewall around to passenger side into cabin and to pin 30 on eec. The white pink continues through plug and to the reverse switch shifter plug at tranny... not landing on anything its just a loop. From there it goes back through same plug in driver kick panel and to clutch switch. This circuit has 2.7 volts on it even with a brand new ignition switch.
    #16
  17. missin'5.0

    missin'5.0 New Member

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    Ok so pin 30 is puttin 4.5 volts. I clipped and verified that, started car and now it will advance timing but it idles around 1400 rpm
    #17
  18. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Did you verify that the proper O2 sensor harness is being used?
    Are the proper wires on the O2 sensor harness being looped for use with a 5 speed transmission as described in my previous post?
    #18
  19. Gearbanger 101

    Gearbanger 101 we love us some gays up here Super Mod

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    You say it runs normally when you "get on it". What do you mean by that. Do you have to stand on it to get the voltage to normalize, or just bring up the idle slightly? Could be a bad battery as LarsD stated, or even a weak alternator. Are you running underdrive pullies by chance? What's the alternator putting out at idle?
    #19
  20. missin'5.0

    missin'5.0 New Member

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    Yes its the right harness, ive drove the car 4 yrs since I did the swap, no issues. 14.4 volts at idle. I have a 3g alt. No it runs normal with the clutch pushed to floor....as when I push clutch it takes the stray voltage off the start clutch safety switch circuit
    #20

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