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Thread: What is going on?

  1. #26
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    Agreed. I hate doing the swap tests too and probably most other owners on here but, it does help to save throwing parts at the problem.
    I went down this path several years back and spent almost 2 years troubleshooting the problem before figuring it out.
    Many new parts were thrown at it including sensors, spark plug sets, coils, O2 sensors, Cats, fuel injectors, intake manifold gaskets, and so on and so on.

    Along the way, I went from LHM to vacuum leaks, and other headaches. I finally replaced the engine wire harness and it fixed the LHM for good.

    Now, not sure why LHM is coming back in short times and low hours on the odometer. I will check the cap/rotor to verify that the source for spark is good.
    I do have spare CIDs so I will use it for testing as well and will report back.

    - - - Updated - - -

    Thanks everyone for your input so far. It does help me to think straight and somewhat sane.

  2. #27
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    Swapping Mafs is a good idea when considering a purchase, You say both sides run crappy? and both exhaust are equally warm?

  3. #28
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    No, the bad side is the driver side...consistent. Driver side exhaust is cold and I can touch the motor block without getting burned.

  4. #29
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    Have you swapped the mafs to see if the limp swap sides?

  5. #30
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    Yes, I have. The LHM did not swap. Still the driver side so makes me feel somewhat confident that the MAFs are okay.

    I tested the MAFs two ways:.
    1: disconnect the MAFs connectors on passenger and driver side one at a time. When the MAF supporting the passenger side was disconnected, engine died immediately. When MAF supporting the driver side was disconnected, passenger bank ran without a hiccup.
    2: swapped MAFs across. Still, passenger side runs fine(smooth). Driver side still in LHM. Disconnect the MAFs connector like above and same exact results as described above.

    So, driver side is definitely in LHM.

    Quote Originally Posted by 8eights View Post
    Have you swapped the mafs to see if the limp swap sides?

  6. #31
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    When you slightly rev, Do CEL go off briefly? If Mafs check out, I would say it's time for a fuel pump 99% of the time.

  7. #32
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    I am going to throw this out there, but I just had an identical issue to the OP and it turned out that one of my fuel pump fuses had a hairline crack. I actually had to pull out the fuse and look closely at it. It was still one of the original fuses (fusible link style). I R2 the fuse and all was right with the world.

  8. #33
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    Quote Originally Posted by ChrisFuture8 View Post
    No, the bad side is the driver side...consistent. Driver side exhaust is cold and I can touch the motor block without getting burned.
    If the drivers side exhaust is cold, then you have a problem on the passenger side bank - V12's have a cross over at the engine -drivers side airbox to intake runners are for the passenger side of the engine (#1-#6), however the distributor on the drivers side is for the driver side...
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  9. #34
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    Interesting, 8Eights and possibly others have implied fuel supply issue as well. Will check that out too. Thanks.

    Quote Originally Posted by rotomoto712 View Post
    I am going to throw this out there, but I just had an identical issue to the OP and it turned out that one of my fuel pump fuses had a hairline crack. I actually had to pull out the fuse and look closely at it. It was still one of the original fuses (fusible link style). I R2 the fuse and all was right with the world.
    - - - Updated - - -

    Yes, roger that Stef. The MAF on the passenger side regulates airflow for the drivers side intake. The rotor/cap/coil/spark plug cables, and CID on driver side is for the driver side.

    Thanks for the reminder.


    Quote Originally Posted by TxGR8White View Post
    If the drivers side exhaust is cold, then you have a problem on the passenger side bank - V12's have a cross over at the engine -drivers side airbox to intake runners are for the passenger side of the engine (#1-#6), however the distributor on the drivers side is for the driver side...

  10. #35
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    Chris, in one of your first posts you wrote "I can definitely smell the raw fuel at the exhaust of the driver's side."

    I'm not convinced it's a fuel supply problem and believe what you are smelling is unburnt fuel due to spark mismanagement, hence a bad or dying CID.

    I know that is *could* be a lot of the other things but you've swapped most all of that between sides with no change. Add the fact that from my own personal experience a failing/failed CID will NOT throw any errors at all, and your symptoms point to a bad CID. I know changing out the donut isn't the easiest thing to do unless you get the right tools and such. I my case, fortunately the after market maker of my spark plug wires was right up the street from my house so all I had to do was ask them to test out all the plug wires and replace the donuts which they did for $30 bucks. Right after that, the car came back to life from the same. exact. symptoms...

    I do hope you get it sorted soon.
    Taylor in Cardiff

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  11. #36
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    A failed CIS still allows the affected bank to run in lost-spark mode for a couple of seconds - and then the lack of a cylinder identification signal received by the ECU inhibits the injectors.

    As your injectors are firing then the CIS is probably working - and you possibly have no fuel pressure....
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  12. #37
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    Hi Taylor,

    I just performed a but more testing. Took the acoustic noise cover off and out the mechanic stethoscope to the driver side fuel injectors. They are not firing.

    Sent from my SM-G955U using Tapatalk

  13. #38
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    So, no fuel to the driver side which means whatever unburned fuel in the exhaust system is blown out st this point.
    To the other poster, the fuel pump fuses are good. Ohms out to about .2ohm...give or take due to the inherent metal material characteristic.
    So, I will check on the CD sensor and am taking the cover off cap/rotor to verify as well.

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  14. #39
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    Hi Tim,

    My initial thought of the fuel injectors firing is INCORRECT. It does not fire after the motor fires up.

  15. #40
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    So I removed the cap/rotor and cleaned the contact points slightly with sand paper. I also wiggled the spark plug cables including the CID donut on cable 12. I reinstalled the cap/rotor and restarted the motor.

    Results:
    The driver side fired up and I can hear the fuel injectors (FI) ticking. It's delivering fuel but at a very slow rate like, "tick...tick...tick" vs. "tick-tick-tick".
    The cap/rotor doesn't look bad at all as they are also 4-5K miles new. The signal received on cylinder #12 by the donut is faint so the DME regulates the FI accordingly.

    I will look for my old stash of spark plug cables with CID and just swap that one cable out to test.

    Stay tuned...will report back.

    - - - Updated - - -

    Quote Originally Posted by 8eights View Post
    When you slightly rev, Do CEL go off briefly? If Mafs check out, I would say it's time for a fuel pump 99% of the time.
    Hi 8eights. Earlier when I tried your test, the CEL light came on and off on its own. It was not responding to throttle input.

  16. #41
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    Pull plug #12 and inspect. If this plug is fouled, the sensor won't read. Also, I didn't see if you swapped the coils... do this if you have not already.

  17. #42
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    Plug #12...gulp, I admit, I'm afraid of that one. Coils are as new as the spark plug cables but will try that too since it's a quick swap.

  18. #43
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    While in there, I would also check that the plugs are seated correctly, not loose.

  19. #44
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    Updates:

    1: Pulled plug #9 and checked for spark with a spark checker
    Result: Yes, has good spark but also slow blink. Plug is clean as well other than the wet fuel residue.

    2: Pulled plug # 12 and checked
    Result: Plug condition is like that of #9. Good shape and wet with fuel.

    3: Replaced cylinder #12 spark plug cable w/ CID sensor with another cable.
    Result: No improvement. Still in partial LHM

    4: Tightened spark plugs to ensure good firing/spark

    5: Changed DME connections around
    Result: No improvement. Still partial LHM

    6: Swapped ignition coils
    Result: No improvement. Still partial LHM.

    So while the car is in LHM, if I give it throttle, the driver side will misfire/protest. Is that a symptom of fuel starvation?

    I don't have a fuel pressure tester so I don't know if I can test the fuel flow pressure properly. I squeezed the two sections of rubber fuel hoses by the firewall that to the fuel injector rails. One looks to be filled with fuel as it's fully expanded. The other one is just slightly soft (where I can slightly squeeze it with thumb and index fingers).
    Last edited by ChrisFuture8; 11-14-2017 at 09:31 PM.

  20. #45
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    99% of the time,) You can switch the fuel lines to be sure, Just depressurize them first by pulling the fuel relays and starting, It will die quickly.
    Last edited by 8eights; 11-14-2017 at 09:33 PM.

  21. #46
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    Alright, I'll give that a try and report back. After this, I'm sort of out of ideas. And the only thing left is for me to raise the car and check the O2 sensors.

    Quote Originally Posted by 8eights View Post
    99% of the time,) You can switch the fuel lines to be sure, Just depressurize them first by pulling the fuel relays and starting, It will die quickly.

  22. #47
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    What is going on?

    Sorry... I know I sound like a broken record... MAFs. Did you swap those or just unplug?


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  23. #48
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    Quote Originally Posted by adwebinc View Post
    Sorry... I know I sound like a broken record... MAFs. Did you swap those or just unplug?


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    No worries. I swapped the MAFs...made no difference. The same bank still in.partial LHM


    Sent from my SM-G955U using Tapatalk

    - - - Updated - - -

    8Eights. Where are the fuel relays located?

    Quote Originally Posted by 8eights View Post
    99% of the time,) You can switch the fuel lines to be sure, Just depressurize them first by pulling the fuel relays and starting, It will die quickly.

  24. #49
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    Pulled fuel lines and switched. No difference. Driver side still partial LHM.

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  25. #50
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    I'm not sure why y'all keep going back and thinking it is on the fuel side... the plugs are all wet with fuel, which means fuel is getting in but not ignited. To me, this points directly at something in the ignition circuit. Spark Tester doesn't really measure how much HV comes through, just that some does. Are we sure both the cap and rotor on that side are not fooked somehow?
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