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P1371: Which wire in Shbox's schematic?

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  • P1371: Which wire in Shbox's schematic?

    http://shbox.com/1/95_ign_system_schematic.jpg

    Between the opti harness and ECM, is it the pink/black stripe, or the red/black stripe wire that is usually the cause of the P1371 code. I called a service dept and the guy told me it was the red/black stripe.

    I just replaced distributor No. 4 and still no fire. When i clear the code, it reappears after a few tries. I replaced the harness between the Ignition System Test Connector (ISTC) and the opti unit because of corrosion on the contacts. I replaced the water pump and all hoses just in case.

    I am coing to test for continuity between the opti harness and ECM. If it checks out ok, i am ordering the Dynaspark. The brand of the replacement Opti is ACardone. DO NOT BUY THIS BRAND OF ANY PART. I had to warranty out distributor No. 4 and now if everthing is ok on the wires from ISTC to ECM, i am warrantying out No. 5

    My brother also bought a ACardone distributor for his 92Z. The bearing seized within 4 weeks of conservative driving. When he removed it, the thing would not even spin at all!! Boycott ACardone!
    -Ryan-


    1997 Pontiac Firerbird Formula LT1/T56
    2006 Pontiac G6 GTP, 3.9L V6, 6-spd

  • #2
    The correct schematic is thes one for 96-97s: http://shbox.com/1/1996_ec_03_ign_system.jpg

    Red/black would be the low resolution from the opti to the PCM.
    Rob B 95Z A4 Tech Page (Part numbers / locations, how to's, schematics, DTC's...) Home Page - shbox.com

    Comment


    • #3
      Let me get this right: the code P1371 is triggered when there are too many pulses coming from the (Low resolution) optic sensor. Which could mean there is debris on the optic sensor, or debris on the shutter wheel on the same path as the 4-slit references?

      OR

      the harness could have a short, or crapped up contacts on either side? I have ruled that possibility out because the harness is brand new. It would make more sense that the distributor was either misassembled, assembled with not enough care, or mishandled somewhere along the way.

      Does the low resolution signal correspond to the 4-slits, and the high the 360-slits?

      Is there only one actual (eye) optic sensor? or two, 1 for the (High res) 360-slit references and 1 for the (Low res) 4-slit references?
      -Ryan-


      1997 Pontiac Firerbird Formula LT1/T56
      2006 Pontiac G6 GTP, 3.9L V6, 6-spd

      Comment


      • #4
        The P1371 code sets when the PCM sees 720 high res pulses (4 rotations of the crankshaft/2 rotations of the camshaft), without detecting a low resolution pulse. Its not "too many" low res pulses, its NO low res pulses.

        Hook up a volt meter to the red/black wire and a ground. Slowly rotate the engine. As the engine rotates, the voltage should move up and down, either 0V or 5V. The signal is a square wave. You get 0V when there is no slot in front of the optical receptor, and 5V when there is a slot, allowing light to pass through.

        The optical wheel has 8 slots for the low res pulse. The slots are 4 unequal-length slots, alternating with 4 narrow, fixed-length slots. The 8 slots reperesent 8 cylinders. The PCM knows which cylinder to fire the plug, or pulse the injector, based on the length of the signal from the unequal length slots.

        If you have the 0V/5V variation on the red/black wire, you have a working optical module. If you don't the optical module is not working. If you have the 0V/5V variation, you have to verify that the signal is making it to the PCM. That requires either checking the continuity of the wire from the Opti to the PCM, or actually measuring for the same voltge swings at the PCM end of the wire.

        Yes, high resolution is 360 slots per cam revolution. Each set of slots has its own LED emitter/receptor to generate the pulse.
        Fred

        381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

        Comment


        • #5
          Thanks for the clarification Fred. I can visualize the square oscillation (Voltage vs. Time) graph.

          When you say slowly rotate the engine, should i do short, burst-like starting attempts? I just have a semi-fancy multimeter (with a "continuity" setting as well as voltage), will that suffice? I would use the volt setting when i crank it, and the cont. setting for when i look for a short somewhere in between the opti and PCM.

          Another thing, my brother has a data-logging program on his computer. Is there anything similar that you recommend for LT1s?

          Thanks again
          -Ryan-


          1997 Pontiac Firerbird Formula LT1/T56
          2006 Pontiac G6 GTP, 3.9L V6, 6-spd

          Comment


          • #6
            You can simply rotate the enigne with everything in neutral, and a breaker bar and socket on the crankk hub bolt.
            Fred

            381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

            Comment


            • #7
              Originally posted by RAF7789
              Thanks for the clarification Fred. I can visualize the square oscillation (Voltage vs. Time) graph.

              When you say slowly rotate the engine, should i do short, burst-like starting attempts? I just have a semi-fancy multimeter (with a "continuity" setting as well as voltage), will that suffice? I would use the volt setting when i crank it, and the cont. setting for when i look for a short somewhere in between the opti and PCM.

              Another thing, my brother has a data-logging program on his computer. Is there anything similar that you recommend for LT1s?

              Thanks again
              There are a few options, when it comes to data logging, but you will need a laptop, cable and the software.
              Greg W. in West Michigan
              1992 Formula WS6-A/R Rims, Stock L05 swap, Former Abuse Victim
              1983 Z28-Parts car- *Sold*
              1984 Z28-305 HO Auto *Sold*
              1986 Camaro-V-6 5Spd *Sold*
              1984 Camaro-V-6 Auto *Sold*
              <Motor out

              Comment


              • #8
                There are a lot of data logging programs for OBD-II. AutoTap is the one I use:

                http://www.obdii.com/obdii.html
                Fred

                381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

                Comment

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