Please Help O2 Sensor Hookup 5.0 Swap

Tbird8850

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Jun 1, 2016
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Okay so this may be a little long but want everyone to know the story behind the car so any answers I get will have the whole story. Its an 88 t-bird turbo coupe with a 5.0 swap. When the car was first swapped it was a 5 speed car and now has a built AOD in it. The issue is the car breaks up and boggs down to what seems to be fuel starvation only at wot. Up to 3/4 throttle car runs good and idles well. What I know is the car used to be supercharged running a Paxton unit. I believe that is why it ran fine before. The o2 sensors are disconnected forcing the computer to run in open loop and the boost would mechanically force fuel through the use of the FPR at wot but now there is no forced induction no added fuel pressure and therefore I think this is my issue. If my o2 sensors were connected it would run better in closed loop. Now the car still has an A9L computer and I have read about frying the computer issues due to the computer getting power through a port that is supposed to see ground from a neutral switch. What can I do to make my setup work? I am willing to make up a harness or whatever I just need to know if its doable and howbto hook it up? Power or ground or???? Any help would be appreciated.
 
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Tbird8850

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I should also include the car has 24lb injectors, a 90mm mass air calibrated for the injectors, a fenderwell cool air intake, gt40 upper and lower, Mac flowpath headers, xpipe with flow masters and dumps. When I tried setting fuel pressure at a normal base 36, 38 or so it breaks up lower in the rpm range in order to run up to 3/4 throttle I am running 44 lbs fuel pressure at idle which makes it boggish down low. hElp:bang:
Search out @jrichker on this forum- he has every fox wiring schematic posted you will ever need to build your harness

Thanks I reached out to him.
 

jrichker

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The problem is with the O2 sensor harness and how the start circuit is wired through the O2 sensor harness.


Here's what I know so far.
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

?temp_hash=80c1e17d46ac51f7e7f8cbbe0869fbb0.jpg

Not all wires are shown for clarity and simplicity

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 may 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.
The 4 cylinder O2 harness uses 4 wire O2 sensors. It probably won’t work correctly without modifying it.
 

Tbird8850

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OK so I bought and auto sensor harness on eBay and I am going to pick up a c3w auto EEC this weekend. The harness does not exist in the car currently. If I plug in the c3w it should run how it does right now correct? Then all I would have to do is install the o2 harness and tap in wherever I need to? How will I need to tie in the harness for the o2 sensors?
 

Sn95 bryqn

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Where is the sn95 o2 sensor harness ground location and where should it be connected ?
 

jrichker

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Where is the sn95 o2 sensor harness ground location and where should it be connected ?
The O2 sensor ground is in the engine mounted fuel injector harness. It gets grounded to the back of the passenger side of the cylinder head or to one of the lower intake manifold mount bolts.

See the graphic for the 10 pin connector circuit layout.
salt-pepper-10-pin-connectors-65-jpg.68512.jpg





The following are diagrams courtesy of Tmoss & Stang&2birds


Engine mounted fuel injector harness
mustangEngineHarness.gif



Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:
TPS_IAB_Pic.jpg


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.

94-95 Mustang wiring diagrams
http://www.veryuseful.com/mustang/tech/engine/#95-95Diagrams

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

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.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

Mustang 5.0 Lights and Radio schematic, by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.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

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg

Convertible top motor wiring http://www.veryuseful.com/mustang/tech/engine/images/mustang88VertTopMotorCkt.gif

Engine mounted fuel injector harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangEngineHarness.gif

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/TPS_IAB_Pic.jpg

Starter circuit
http://forums.stangnet.com/attachment.php?attachmentid=21328&d=1080916057

Alternator diagram for 94-95 Mustangs.
http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-Alt.gif
 
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fredfifty

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Nov 23, 2011
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im getting conflicting info..that o2 sensor looped wire for the t5 looks to be for years 88-90 according to this website http://ponyperformance.com/ (go to technical and scroll all the way down to the o2 sensor harness identification). years 91-93 have a different looped wire (see diagram in attachment in the link)

who is right?