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Advanced Engine Diagnostics help

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by losh1971, Aug 10, 2018.

  1. EYY

    EYY Well-Known Member

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    yep won't even be going into lean cruise in that case. I ran new wires from pcm to o2 sensor for mine and it fixed it when I had the old engine management (424 pcm same as yours but 5L). Broken wires seem to be pretty common. Probably get brittle from heat over time.
     
  2. losh1971

    losh1971 Well-Known Member

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    This is the latest scan. It goes from not ready to ready but still doesn't fluctuate.

    upload_2018-8-10_17-24-57.png
     
  3. losh1971

    losh1971 Well-Known Member

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    Mileage is pretty good but it sounds like I can improve on that if the O2 sensor issue is fixed. I am just totally confused with the method given to fix the issue as it makes no sense in my head. Error code is 13 meaning no signal, so I am pretty confident it is the ground issue causing the prob.
     
  4. EYY

    EYY Well-Known Member

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    Knock detected, Vats signal missing, Lean indicated (could be related to missing o2 signal)...

    Seems a bit strange. Knock can be related to a number of things including bad engine mounts, vac leak, bad fuel, weak ignition system etc etc. But really need to work on one problem at a time, o2 circuit being the first. VATS signal missing - your new memcal may have VATS turned off.
     
  5. losh1971

    losh1971 Well-Known Member

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    I have always had security disabled. I believe it is disabled in the BCM. Scanned it 18 months ago with Snapon and it was disabled back then. O2 issue has only been happening for maybe six months.
     
  6. EYY

    EYY Well-Known Member

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    All you need to do is replace the one signal wire to the pcm - if you can solder some wire you’re good to go. Just look up vr v6 wiring diagram (pretty sure the diagram is on pcmhacking). Find the pin that corresponds with the o2 sensor and remove/replace that wire. Could even just be an issue at the plug end.

    Can use a multimeter to check for resistance/continuity too.
     
  7. losh1971

    losh1971 Well-Known Member

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    do i run a new wire from the sensor right up and somehow connect it to the PCM? Do i need to drill a hole in the floor to run this wire? I tried the multimeter but couldn't work out how to test the wires, as i can't connect the plug on the 02 and PCM at the same time
     
  8. losh1971

    losh1971 Well-Known Member

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    EYY did you just chop the wire off just before the plug and splice a new one in? I had a look a few weeks ago and am just as confused now as i was when i climbed underneath trying to figure out the fix before giving up because I couldn't work out what to do.
     
  9. losh1971

    losh1971 Well-Known Member

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    I looked at the plug and couldn't see any problems. Is it a big job? I'm just not sure i can work out what to do. If it is fairly easy for a mechanic i can just book it in but if im gonna be up for 200 bucks or more then i need to live with it. For all i know the plug is faulty but I'm thinking its beyond my capabilities.
     
  10. losh1971

    losh1971 Well-Known Member

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    The plug could be faulty but i can't test it. I know I had to replace the plug on the speed sensor because a previous owner had arildited it. The clip is missing on the plug so i have put a zip tie around both sides to ensure it can't come apart.
     
  11. EYY

    EYY Well-Known Member

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    To connect the plug you can use a piece of wire pushed into the plug to extend it enough so that you can take a reading. No need to drill holes - you can feed it through the firewall grommet (may need to do this with a bit of coat hanger wire). Even just to test it you could connect the wire to the pcm, run it out the window and down to the o2 sensor signal if you wanted to confirm that wiring is the problem

    If you were able to fit a memcal and do your own diagnostics I’m sure you can sort the wiring too. :)
     
  12. delcowizzid

    delcowizzid on holiday

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    If the o2 says ready it must of come up to temp and started outputting a voltage what is the o2mv at idle should be in the 0.800s
    Get tunerpro working so you can do a lot and playback data and upload a log file here for us to look at
     
  13. losh1971

    losh1971 Well-Known Member

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    I get "ready" sometimes and other times it says not ready, more often it will say "not ready".
     
  14. losh1971

    losh1971 Well-Known Member

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    I am wondering if the best thing to do is to go to the self serve wreckers and try to pull an O2 harness. Gonna depend on if I can unwrap it from the PCM right down to the sensor. At least that way I can easily test it for continuity, including the plug.
     
  15. losh1971

    losh1971 Well-Known Member

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    OK thanks to Boozer I have a good wiring diagram. Question if I replace the harness is it just a matter of running the four wires to the PCM? Or do they divert through the data connector?? Thinking if I can get another harness and plug I can rule that out. I will have no trouble splicing new cable into a harness that I pull from a donor if it is just then a matter of chopping the old one off and connecting a new one to he PCM. Like I said the plug on the O2 loom might be faulty given a previous owner botched the speed sensor plug and it's in the same location.
     
  16. losh1971

    losh1971 Well-Known Member

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    Been thinking about it and making a whole new harness is too hard, due to heating cicuit running from the fuse box. Thinking the best thing to do is still get a harness from a wreck as my plug could be faulty. Going to temp tape in a new plug and see if that fixes it. If it doesn't fix te issue i will run a new signal wire through the window as you mentioned EYY. If it is still faulty i will run a new ground as well. Once i get it sorted i will run the cables neatly along the existing harness and use Jaycar solder joiners to make it permanent.
     
  17. delcowizzid

    delcowizzid on holiday

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    So some simple checks first unplug the o2 grab your multimeter.turn the key to ignition and grab the loom plug test for 12v between the pink wire terminal and the black wire terminal right beside it.if you have 12v good the heater will work if its low set the multimeter on ohms and test resistance from that pin beside the pink to the earth on the engine or gearbox. Do the same for the very end pin furtherest away from the pink
     
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  18. delcowizzid

    delcowizzid on holiday

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    Or log it with tunerpro tunerpro and send me a log to look at
     
  19. losh1971

    losh1971 Well-Known Member

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    Can i do the same with AED? Only because it is easier to use.
     
  20. losh1971

    losh1971 Well-Known Member

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    Delco i have some less than ideal battery grounds. Old owner has fitted them. I will take a pic and post them. Thinking they need to be redone. Can you please let me know what you think?
     

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