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Thread: Ecm

  1. #11
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    Good stuff guys and you are right that there is an issue with the electrical connection between the rear subframe and the main frame but only when you're putting 100cold cranking amps through it.The ECM is probably only pulling 300 milli amps and I have gone round the various consumers and measured the voltage drop on both the power and negative sides to see if there is a bad connection between them and the battery when they are powered up and the worst is less than half a volt .34nineteen might be right as both coils are similarly affected and that's getting a bit coincidental for me as the only common thing on the two coils is the power supply ,which is fine ,and the ECM. Separate spark plugs , HT leads , secondary windings and primary windings but the same weird primary voltage pattern and that is controlled by the ECM.
    M

  2. #12
    Senior Member Cooter's Avatar
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    I wouldn't obsess over a weird primary signal with a oscilloscope, it isn't points opening and a condenser charging

    The ECM gets its trigger signal for BOTH cylinders from one timing trigger (one wire), then it splits and times (in the ECM) for EACH cylinder (2 wires, one for each coil primary). Like I asked before, if you have spark... why are you still checking for spark?

    The bike has a history of fuel issues, I'd look there. 49psi is spec and you can trigger injectors (and the coils) under tests in ECMDroid.

  3. #13
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    Well it is true that I have not checked fuel pressure but the reason that I'm leaning to an ignition fault is that I can smell fuel in the exhaust and both plugs are wet , they are the standard 9E NGK's rather than the 9EIX iridiums but they should still fire up the motor ,
    There seems to be a good signal from the cam sensor but is it properly timed to the cam .I had a non start Porsche 964 that also used a hall effect sensor but in the distributor rather than on the cam and the locating peg had sheared so whilst there was good signal from the hall sensor it was all over the place and that was easy to find as that engine also had a crank sensor so all you had to do was get both signals up on screen under cranking and you could see the dissy signal floating about , but does the Buell have anything that I can reference the cam signal to,
    M

  4. #14
    Senior Member Cooter's Avatar
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    Ya wet plugs is a clue for sure. Does it spit/sputter/backfire? or just crank over? Buells foul plugs VERY easily and only a few repeated attempts to start will do it.
    A static timing check is as easy as rotating to TDC and checking the reluctor on the timing wheel behind the riveted cover.

    http://buellmods.com/#TabbedContent

  5. #15
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    Jan 2021
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    Found a TDC mark on the flywheel under a plug r/h side of engine and the cam sensor setting looks fine ,took the l/h side of the rear subframe off to clean up the earth points and it looks like it was sparking between the sheet steel battery holder and the alu side spar so that is now all good.
    I'm waiting for a diagnostic cable to get here and then I'll have another crack at it , but I have too much paying work to do and I shouldn't really be messing with boys toys
    Thanks for the ecm info and the link to IDS , it's good to know that this a programable ECM and that I can sort this fine looking motorcycle out.
    M

  6. #16
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    Before changing an ECM or any other part you really should do some simple diagnostics using a Buelltooth and Ecmdroid. If you do have to replace the ECM you're going to need them anyway to do a TPS reset. You can also test the spark plugs, injectors, and fuel pump. Like Cooter said, Uly's can be hard on ECMs but they usually "act up" before giving up the ghost. You could have a fuel pump problem or any number of things. Changing parts based on a hunch instead of data isn't cost effective. rev-mo.com/efitroubleshoot may help you.

  7. #17
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    Diagnostic cable got here today so I got it hooked up with ecmspy and talking to the ECM - no faults stored
    M

  8. #18
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    Thanks for your interest Upaero and diagnostics is exactly what I am doing ,no new parts have been bought yet
    M

  9. #19
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    If your ECM had the "Uly" problem you would see a laundry list of stored faults. Check your AFV which will tell you if the ECM has been compensating for low fuel pressure.

  10. #20
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    what's the "Uly" problem?
    M



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