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Dirt Track SC2

  #1  
Old 01-07-2019, 09:52 PM
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Well, I bought a 95 SC2 with a 1.9 L Dual Overhead Cam. We brought it home and ran it around and everything worked great (even "performance mode") needless to say we began to take it apart wires were cut that we thought to be unnecessary (speaker wires etc.) as well as disable the air bags. However when we tried to move the car it seemed we had a short that caused the brakes to stall the car and turn the parking lights on. we got it to the point that the brakes didn't kill it but the lights get brighter the more gas you give it and it is running so rich that the car is still stalling out. I would appreciate any ideas as to what is going on with my car as well as any links to full wiring diagrams.
 
  #2  
Old 01-07-2019, 10:23 PM
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Sounds like you cut some computer to sensor wires. Is it a manual or automatic car? Derf may have the wiring schematics for your car. Maybe you opened up the ground circuits in the dash and now have a floating ground.
 
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Old 01-07-2019, 10:26 PM
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It is an automatic. and that's great I would love to get my hands on them. How would I check a floating ground?
 

Last edited by BakerSC2; 01-07-2019 at 10:29 PM.
  #4  
Old 01-07-2019, 11:37 PM
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Change in brightness w rpm usually means voltage regulator problems. It's inside the alternator. Put a voltmeter across the alternator to chassis ground. The voltage should be a steady 14.4 ish at idle. If it is stable but significantly below that V, one or more of the alt diodes is fried. If it is bouncing around at idle, the voltage regulator is likely fried. This is all assuming your serp belt is not slipping.

Also check the v across the battery while running and 30 min after turning off the car.

After looking at schematics, I'm still puzzled how the parking lights would be powered with the stalk switch turned off. One of the few ways for the lamps to get V is if you have a batt V dead short to ground and the ground wire is now carrying 12V and current is running backwards through the lamp, but that means there must be another lower potential point for the circuit to complete itself and current to flow.

I'm thinking you must have had a batt + or alt output short to ground in such a way that the fuseable link is not blown (assuming battery is still charging) or the battery to chassis ground was/is loose and the ground potential was moving around.

If you spike enough of a current dead shorting the alt output or Batt+ voltage, or suddenly changing the ground potential, you can damage not only the alternator and battery ---you can damage the PCM which on a 95 is year, model, and I believe transmission specific. I know this as I too have a 95 SC2.

You didn't mention anything about burned fuses nor what the cause was for the brakes stalling the vehicle. I've had that happen with a thoroughly toasted battery where apparently the alternator could not supply enough current and needed to pull from the batt, but it held no charge, so, lights out.

Please search paperclip method on the forum and report back with the diag code numbers. That can serve as a starting point regarding what isn't functioning properly.

Also, please post pics of what you cut and where. I'm willing to help you un fubar if possible, but I need to know with certainty what I'm looking at w r t wiring as the diagrams I have cover 91 to 95 and are presented as "typical". Some pages actually are variations of others. It's somewhat of a fustercluck but we'll have to make due.

Burned fuses
How you stopped car from stalling on brake press
Alt and batt V's
Diag codes via paperclip

(Please)

Derf
 

Last edited by derf; 01-07-2019 at 11:41 PM.
  #5  
Old 01-08-2019, 12:59 PM
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Thank you, I will post some pictures when I work on the car again. I will also check the volts like you said. Do 95 SC2's have a mechanical fuel regulator? Could that be what is making it run rich at low RPMs?
 
  #6  
Old 01-08-2019, 04:26 PM
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More likely the ECTS or associated connector/ wiring is the culprit. Often the car is hard to start and runs rich. If the issue only started after the electrical snag, it may also be that part of the PCM that controls when the car goes into closed loop control is damaged. But that is conjecture, which is why we need the codes.

In general, the early s cars run obscenely rich until closed loop kicks in. But should not be enough to stall the car.

If you choose to replace the ECTS, use only the all brass ACDelco / Delphi sensor and replace the connector pigtail as well. About $45. Aftermarket sensors are not calibrated for specific cars and often lead to totally avoiabavo overheating, which, if you're racing, I'd think you'd want to avoid.

There are 2 coolant tep sensors on the 95. The 2 wire sensor located in the head, driver's side is the one to replace. Squeeze connector. The single wire temp sensor drives the dash gauge.

As for your original question (sorry), IIRC the fuel pressure regulators on the 1st and 2nd gen S cars are vacuum controlled and usually not a problem. Do not try to adjust it. You can always hook up a fuel pressure gauge to the port on the rail and monitor it in real time.
 

Last edited by derf; 01-08-2019 at 04:31 PM.
  #7  
Old 01-08-2019, 04:30 PM
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GOOD NEWS we have located the problem so we think. we have a continuous loop in the light wiring harness which seems to be intertwined with or at least impacting the fuel pump. The question I have now is which of the two groups of wires control the fuel pump? the plan is to bypass the now unessisary B.S. and put in a switch for the fuel pump (which is required for the track).
 

Last edited by BakerSC2; 01-08-2019 at 08:01 PM.
  #8  
Old 01-08-2019, 10:10 PM
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Twisted pairs are usually sensors fyi. Speed sensors or other computer sensors that they don’t want interference on.
 
  #9  
Old 01-09-2019, 05:07 AM
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Okay thank you. which color(s) is fuel pump though
 
  #10  
Old 01-09-2019, 12:34 PM
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Will look in a bit
 

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