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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
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ele. prob.?

  • Thread starter Thread starter 94 cobra
  • Start date Start date Jan 29, 2006
9

94 cobra

New Member
Oct 12, 2005
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0
0
Jan 29, 2006
#1
  • Jan 29, 2006
  • #1
ok here is the deal hooked up my nos. and like a dummy ran it off of 2 power wires
from the cig. lighters the first time i used it my temp. went right over past the red and oil pressure did the same . so i thought i blew a head gasketpulled it apart didnt see any where it might have leaked so bought new gaskets and put it back to gether (it also seemed like it over heated water comming out of over flow) and the same thing but the only time water came out of the overflow when i first filled it with water( air in the system?) and when i turn on any acc. my temp and oil press. goes up the more i turn on the higher it goes could it be a bad ground or still a head gasket i didnt have the heads checked no oil in water and when its cold no bubbles in the coolant or oil. ant sugestions?
 

jrichker

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#2
  • Jan 29, 2006
  • #2
Stock gauges or aftermarket gauges?

Never replace head gaskets without running a compression test. The $35 for a compression tester is cheaper than gaskets and labor.
 
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94 cobra

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Oct 12, 2005
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#3
  • Jan 29, 2006
  • #3
stock gages its on a 94 cobra.
i figured the high oil pressure was water in the oil.
 

jrichker

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#4
  • Jan 30, 2006
  • #4
Check the grounds. Grounds are important to any electrical system, and especially to computers.

1.) The main power ground is from engine block to battery: it is the power ground for the starter & alternator.

2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. Any car that has a 3G alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects.

3.) The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery. It is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire. The wire goes into the harness at the starter solenoid.

4.) All the sensors have a common separate ground. This includes the TPS, ACT, EGE, BAP, & VSS

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or head bolt.

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself. The TFI module ground is a signal ground that terminates inside the computer.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally.

See http://www.fluke.com/application_notes/automotive/circuit.asp?AGID=1&SID=103#volt for help troubleshooting voltage drops across grounds
 
9

94 cobra

New Member
Oct 12, 2005
3
0
0
Jan 30, 2006
#5
  • Jan 30, 2006
  • #5
damm, i dont think i have half of those grounds i better start there
i did find that if i turn on all my acc. i mean every thing wipers defroster,ect.ect. that i get some smoke comming from e-brake opening and my volts go down to the red and my cd player wont even come on
in the center console i think its trying to ground it self on the e-brake cable
thanks for all the help i will start running new grounds.
its just weard that it started when i used the juice maybe all the power pulled off the ground wire and it broke a motor mount
 
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