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Rough running EZ EFI 1.0

Discussion in 'FAST Support Forum' started by Yadkin, Aug 23, 2016.

  1. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    This confirms what I suspected- I went up too fast on the idle AF. I'll set it to 13.6, enrichment at 0 and try again.
     
  2. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    You'll want to pay attention to what idle A/F does to both cold and warm engine cranking. Cold engine cranking will likely be the most noticeable as you lean A/F, and is especially so with high overlap cams (which shouldn't be a problem with your cam). The right idle A/F will make the initial cold cranking RPMs stabilize more quickly to the ECU set cold start RPM. The bad thing is you only get about one shot at this a day - only after the engine has cooled completely and any remaining fuel has evaporated from the intake. I set cold start after seeing how the engine cold starts over a number of days while watching the RPMs closely at start.

    You want to achieve a balance using the idle A/F first, and then the handheld start enrichment, for best cold and warm start cranking. You'll see a pattern emerge.

    It wouldn't be this difficult, but the ECU uses the warm engine set A/F maps to adjust its internal cranking maps (adding or subtracting from the initial cranking fuel squirt). So, the ECU has to learn each new warm A/F. Go slow, and you should hit optimum settings in a few days time. The color handheld only "fine tunes" the initial ECU crank settings.
     
  3. A A

    A A Well-Known Member

    Joined:
    Jun 22, 2014
    Here's an added piece of information on cold start. When you do the cold start, let it idle and shut the engine off before it warms more than a minute or two - and check a few plugs right away. If you see any raw fuel on them, lean the idle A/F another tenth until you see no more raw fuel. The cold start should continue to be easy - maybe even better. I found one of my engines liked 14.3 sitting at warm idle in gear and didn't show any signs of gas fouling with cold start at 14.3 with zero crank enrichment. I then set the start enrichment for best warm starts. Before I did it this way, the engine appeared to like a much richer idle A/F.
     
  4. Yadkin

    Yadkin Member

    Joined:
    Jul 22, 2013
    Location:
    Yadkin Valley, NC
    Been a while and I've been busy with other things but now I have something to report on the ignition issue.

    Over the 4th Holiday my son was here visiting and we hooked up the oscilloscope, first on the coil wire. We determined that the Second Spark unit does nothing. Set at 1,2,3, or any number up to 9 registers the same on the scope and setting to zero, which the manufacturer states turns the second strike off. Disconnected the engine does not run so it is basically a very expensive tach signal for the EFI unit.

    The shape of the signal is consistent and basically text book. It's more of a buzz than a snap, meaning that the spark is fairly long in duration.

    Next we read each spark plug wire. I found out that I was getting stray signals from the adjoining leads, per the firing order. My theory is that the signals are getting picked up inside the cap, causing misfires and possibly cylinders working against each other. This is a small diameter cap, not a large diameter as per later years when high energy ignitions were introduced. Apparently the reason why the more modern caps are bigger is to space out the rotor contacts for less interference.

    I did screen shots of each so can post if anyone's interested.

    So I bought an OE replacement coil. I haven't scoped it but it should be around 10k volts instead of 45k. Anyway, the car runs a lt better. Still not perfect (probably the cam). But a lot smoother, quieter.
     

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