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Thread: Megasquirt and Variants Running Thread

  1. #21
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Megasquirt and Variants Running Thread

    Well, crap. It didn't start after I returned home from church today. It's getting zero crank or cam signal when I attempt to log it. However, if I jumper power to the crank sensor and look at the signal with my oscilloscope it puts out ~10v square wave. That was with the MS unhooked and a pin in the connector to back probe it with the ground hooked up to the sensor signal ground.

    I'm at a loss on this one. I'll be calling DIY autotune tomorrow to see if they have any suggestions. I'm wondering if feeding the hall sensors off of the 5v reference signal didn't damage the unit somehow?

  2. #22
    turbo addict
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    Re: Megasquirt and Variants Running Thread

    Every Microsquirt is different so it's very difficult to troubleshoot without fully understand and see the quality of installation. Did you solder, did you crimp, size of wires, did you use new or old wires, all those make a difference.

    When I did my built, I used new wires for ALL engine harness and crimped it all. I used on 5v to feed MAP, TPS, and Crank Sensor and One sensor ground to ground them all.

    The problem followed, so what are the parts you re-used? I did NOT want to use the factory HEP for this reason.

    Here is the diagram I made for my car.




    As for Idle, I started with a on/off solenoid, then PWM Ford Idle Valve, then to PWM turbo Volvo BOSCH Idle Valve. Solenoid works great but didn't supplied enough air for a/c compressor and a/c fan, the ford idle valve leaks at Idle, and the Volvo BOSCH Idle Valve is what a TURBO Volvo uses, good enough for my car. All mentioned here. http://www.turbo-mopar.com/forums/sh...ht=microsquirt

    Idle is just a vacuum leak, I drilled/tapped the pre-turbo pipe/after air filter then ran a line from there to one of the port at intake manifold. Used a hose that can withstand pressure as well as vacuum. I plugged the throttle body IAC hole for good.

  3. #23
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Megasquirt and Variants Running Thread

    Thanks for all that. I bought the 8' harness and I used 99% new mils spec wiring for things I needed to add, and new connectors, of which I needed very few as the MS has a map and baro sensor integrated into the unit. The only thing I reused were the connectors with pigtail wires for the LS coils, and then only a couple inches of each one. I did crimp every connection, and I used either genuine Thomas and Betts barrel splices or open barrel splice connectors with the "proper" Delphi crimper. I did test all of the crank and cam trigger wiring with my Load pro, and it checked out.

    I spoke with Randy at DIYautotune today. He suggested that I should have been able to use the 5v reference signal or a switched 12v signal for the crank trigger sensors. After I told him that I checked the wiring with my Load Pro to verify a good power wire and sensor signal wire, along with the fact that I get a nice square wave on the scope, he said to maybe try turning off the pullup resistors.

    I turned off the pullup resistors tonight and the car fired right up. It ran for some time, though with a little loppier idle than before. I made some adjustments to idle settings and attempted to apply the changes by cycling power and restarting the car. Once again, it was dead as a doornail and wouldn't see a crank signal.

    Upon seeing no crank signal in Tuner Studio, I immediately removed the connector and hooked up the oscilloscope. It showed a very nice square wave of around 6v or so.

    At this point, I'm inclined to believe that the unit is internally faulty. Nothing else would explain how the wiring would check out good, and the oscilloscope would generate a signal without fail, while the car sees zero crank signal. The one thing I'm worried about is that this unit will test good on the bench for the guys at DIYautotune but it will continue to intermittently fail in real world use. We'll see...
    Last edited by cordes; 10-28-2024 at 09:22 PM.

  4. #24
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Megasquirt and Variants Running Thread

    I spoke with my father tonight who voiced concerns that the hall sensor could be putting out a nice signal for the scope with no real current flowing through it, but that even the MS trying to read it might be enough to make it a bad signal. I'll take a spare sensor and see if I can hold it up to the trigger wheel while it's cranking to generate a signal. If I can swap back and forth with a reliable change, then I'll hesitate to send off the MS to DIYatuotune and perhaps swap sensors to put on some more miles. I guess either way it'll tell me if my unit is bad since the wiring tests perfectly with the Load Pro.

  5. #25
    turbo addict
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    Re: Megasquirt and Variants Running Thread

    What hall sensor are you using?

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