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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
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engine swap elec problems

  • Thread starter Thread starter Sanford
  • Start date Start date May 9, 2004
S

Sanford

New Member
May 3, 2004
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0
Maryland
May 9, 2004
#1
  • May 9, 2004
  • #1
Ok guys i have one here for ya that im sure isnt in the threads... I have a 94 gt with an older engine 92 i belive... engine is a built 306... the guy i got the car from said it wouldnt run with the stock computer and he put an older style computer in it out of a 91 i think and it runs... the problem is it seems like it will only run in open loop mode, if i hook up the O2 sensors it wont even start, so i have to leave everything disconnected, tps, o2s are all not reading with the computer correctly... i looked in my book and checked voltage on the o2s and i have 9 volts on three of the wires, according to the book that is wrong it should be on a relay with voltage on one wire for like 3 seconds, one hot, a ground and a signal wire.... anyways im just trying to figure out some options... is there any way to run WITHOUT the o2's and have the car run good... i see threads of people saying they do it but my car runs like s&^t unless its WOT... sits there and just blows fuel out the pipes... Help me please the car runs great at wot and i would love to be able to drive it now its a driveway king... i was also wondering about a stand alone system if all else fails $$$ =/ but im running out of ideas..thanks brian
 

tmoss

Gettin Wired
Founding Member
Jun 28, 2001
7,153
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128
Saint Louis, MO
May 9, 2004
#2
  • May 9, 2004
  • #2
Brian, if you need a color wiring diagram of the older EEC wiring to compare to yours, you'll find one at:

www.veryuseful.com/mustang/tech/engine

Make sure the sensors have the 5vdc from the computer as they will not work without it......
 
S

Sanford

New Member
May 3, 2004
15
0
0
Maryland
May 9, 2004
#3
  • May 9, 2004
  • #3
i checked my voltage and on three of the wires i have like 9 volts with the key on at the o2 harness... but see the problem is when the person installed this engine they cut the harness off of the o2 sensors and hard wired them... and used different colored wires just to extend the sensors... so i dont know what is what... am i suppose to have 5 volts on just the supply voltage or what? thanks brian
 

tmoss

Gettin Wired
Founding Member
Jun 28, 2001
7,153
32
128
Saint Louis, MO
May 9, 2004
#4
  • May 9, 2004
  • #4
One wire on the O2 sensor gets 12v from the ignition to preheat the sensor for faster startup time, and another wire delivers the sesnor voltage and the third black wire is the ground.
 
S

Sanford

New Member
May 3, 2004
15
0
0
Maryland
May 9, 2004
#5
  • May 9, 2004
  • #5
i have 4 wire o2 sensors.... i had voltage on 3 of the wires and no voltage on the other... but if i check polarity i have it between one of the wires that has voltage and the one that dosent that dosent seem right to me... like when hooked up it would cause a short? and the other 2 wires that have voltage also have polarity between the 2 of them... argh... =/
 
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