355 - What's wrong with this injector waveform ? | Page 3 | FerrariChat

355 What's wrong with this injector waveform ?

Discussion in '348/355' started by yelcab, Sep 4, 2023.

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  1. m.stojanovic

    m.stojanovic F1 Rookie
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    To me it looks like 4.5 ms.
     
  2. yelcab

    yelcab F1 World Champ
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    I am reading the text underneath the larger picture.

    It said the frequency of the signal is ~9Hz, which is correct for an RPM of ~1050 rpm. It's period is 110 milliseconds, that also makes sense. Which makes the time division to be 20ms.
    It also says the duty-cycle of the waveform is 99.8% positive, meaning 0.2% negative pulse. The smaller pic (first pic) showing multiple pulses sure do not look like 99.8 percent duty cycle. That does not compute.

    But back to the picture that does compute. The negative pulse looks to be 4ms (so 4.5 ms does compute).

    And I cannot explain the time division of 1 microsecond (us)

    Grant still has to compare the pulsewidth among 1/2/3/4, and the 1/5
     
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  3. johnk...

    johnk... F1 World Champ
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    What is the problem with the car?
     
  4. SoCal1

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    LIKE FBB said the wiring is horrible
    I am ordering the Rigol MSO5074 as my usb is poop now so I bow out

    Mitchell I think you got it covered of anyone I know so I'll watch
     
  5. yelcab

    yelcab F1 World Champ
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    Grant, we need pretty good accuracy on the 4.5ms pulse width. The ECU varies this width upto 25% when it wants to pump in more or less fuel. Comparison among cylinders on the same bank, and then comparison to the other bank tells us something.
     
  6. Qavion

    Qavion F1 World Champ
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    The pic on the right shows us, not ms.
     
  7. yelcab

    yelcab F1 World Champ
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    That is why it does not compute. I think that's a bug in the scope display.
     
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  8. taz355

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    The voltage range is 2 volts per division x10 due to the probe being on x10
    I thought it was miss firing and it is running a little rough at idle but is running rich from the ecu adding fuel as fuel trims on bank 1 are 18 long term and climbing
    I checked all vacume leaks and ignition issues and thought I had it solved due to 2 cylinders miss firing on the scope but it seems that 1 pigtail I maid for ease of testing was bad
    Once fixed I am getting good results.
     
  9. taz355

    taz355 F1 Veteran
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    Ok
    The scope as I am learning it does have a bug for recording the waves. It only saves the waveforms in the SCALE you have it set for when measuring.
    Because these were my first tests I used ‘quick save” and it saved them to a reference area likely for you to put in good reference wave forms.
    In order to look more closely at the trace I ZOOMED after the save and it made the wave form larger but changed the scale from 20 milliseconds to micro because I stepped down 4 or 5 times to zoom. So it was not measured at micro but at 20 milliseconds as above photo showed “unzoomed”

    yes Mitchell in order to get you that I will check 1 cylinder at a time zoomed in while I am testing
    The scope has many parameters and I will measure them all and you will see them at the bottom.
    All scales will be correct then as well because I will do a scope picture of the trace. I just can not manipulate it after.

    also it does have 2 vertical and 2 horizontal guides that will calculate both voltage and duration if used. after the trace is done you can manipulate those
    But the only quirk is you can only screen shot it or video it unless I output it to a computer. The scope does not seem to have enough memory to save an active trace other than by leaving the trace on the screen and not shutting it off or trying to save it
     
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  10. taz355

    taz355 F1 Veteran
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    Yes and I will
     
  11. taz355

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    It is overfuelling at all rpm’s except wide open bank 1
    It’s ignition related because once in a while it works for a few seconds.
     
  12. taz355

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    Will due work is busy but Friday night I expect to get a few traces
    It does not take too long with the pigtails fixed
    I will just due 1 at a time and I am thinking trace 1 2 3 and 4 will be in conjunction with the traces
    I also figured 5 6 7 and 8 I will make reverse so 8 and 1 will be trace 1 as you work from cabin to bumper
     
  13. taz355

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    Yes likely
    I think Mitchell nailed it that actual trace was at 20ms and I saved it. When I zoomed the scale changed incorrectly I think because it does not compute by the divisions and it’s the same trace
     
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  14. taz355

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  15. Qavion

    Qavion F1 World Champ
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    Is that the clear one or the white one? Are there any faint identifying marks on it? Without a brand name it would be hard to find.

    If you were repinning all the wires, you could probably find a substitute. e.g.

    https://www.alibaba.com/product-detail/Made-in-China-172496-1-automotive_1600476157312.html

    The key searchword for the example above is "172496-1 9p". Then you'd have to find someone to sell you individual plugs, not 1000's.

    Then you'd have to find heavy duty contacts (pins/sockets) for it. Are the originals round or blade type? I forget.
     
  16. 26street

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    Is this the one


    Sent from my iPhone using FerrariChat
     
  17. Qavion

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  18. 26street

    26street Formula Junior

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    If the car is running rich all the time the pulse-with will be short
    Try disconnecting a vacuum and look at the o2 aka lamda sensor to see if it reacts


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  19. Qavion

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    How are you defining "rich"? What is actually coming out of the tailpipes? Or what is being sensed by the O2 sensors?
     
  20. johnk...

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    ??? If it was running rich and the O2 sensors sensed, it they would tell the ECU to narrow the pulse to eliminate the rich condition. If it could not lean the system out it would throw a CEL as fuel trim would hit a limit. But if it is continuing to run rich do to a malfunction I would expect the cylinders which were running rich to have excessive pulse width. No?

    If it's just the 1-4 bank that is rich it should be straight forward to look at and compare the pulse width on the 5-8 bank with those on the 1-4 bank to see which cylinders on the 104 are rich.
     
  21. taz355

    taz355 F1 Veteran
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  22. taz355

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    Out the tail pipe and the lambdas are actually trying to richer it more and cat glows red if left idle too long
     
  23. taz355

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    That’s what Mitchell said I think
    I took some scans with the aligator clip on the probe wired to back end ground on chassis and probe to the negative on injector these are the latest
    And to me something is not correct somehow it is sensing it needs more fuel but I am pretty sure it’s wrong but the lambda sensors do change
    I am going to remove the spacers again between the lambdas and the sensors
     
  24. taz355

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    #74 taz355, Sep 13, 2023
    Last edited: Sep 13, 2023
    I don’t completely understand this above
    As I repair some minor vacuum leaks and it adjusted ltft from 23 down to 18 so I concluded vacuum leaks will make it run rich.
    Which vacuum line do you think I should try
     
  25. Qavion

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    According to the wiring diagrams, the (positive) power wires should be green/black. The ECU (earth wires) are different colours. Only injector 4 should be yellow only (no stripes). Injector 3 should be yellow/red. Injector 8 should be yellow/green

    How did your signal get so noisy? What does the waveform look like at 1 ms? We need to see the duration of the voltage dip for each pulse (and, perhaps as suggested, look at at least one cylinder on each bank at the same time to see if one side is being fed more fuel than the other).
     

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