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Thread: Megasquirt - direct coil control, no spark

  1. #1
    Junior Member Grease Monkey ra65's Avatar
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    Default Megasquirt - direct coil control, no spark

    Not getting any spark when trying to start the car. Running MSII 3.0 with 2.68 code.

    Have followed this http://www.megamanual.com/ms2/vb921.htm exactly. All settings seem to be fine in megatune. Getting 12v when the ignition is on and cranking. I tried testing the continuity between the negative terminal and ground while cranking but not seeing anything. Just using a multimeter though so I am guessing its possibly not fast enough?

    Getting 150rpm showing when cranking. This is on a 22re with locked dizzy and stock coil.

    Anything else I can check?

    Edit - Just put it on the stim and brought rpm down to 60. Looks like this is slow enough for multimeter to read. Pin 36 was going to ground on every ignition sequence. Looks like the actually megasquirt is probably working how it should. Should I possibly change the spark output to "going low (normal)"?
    Last edited by ra65; 03-11-2007 at 02:33 PM.

  2. #2
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    no, drive the VB921 inverted - do ti the other way and you will toast that driver.

    what coil are you using? and are you sure you have 12V when cranking?

    can you hook up a spark plug to the coil HT out, rest it on the rocker cover for a good earth and see if it sparking when cranking?

    are you using the ballast resistor attached to the coil?

    have you timed the trigger wheel correctly? from the MSnSE instructions i used:
    1) Set the crank at 20BTDC
    3) Make sure the rotor arm points towards the correct contact in the distributor cap
    4) Bolt down the distributor
    5) Turn engine backwards until the pip lines up with the VR sensor
    6) Measure angle BTDC (+/- 10 degrees is good enough) at the crank
    7) Enter measured angle in "Trigger angle"
    8) Enter "Fixed angle" to 10 degrees
    9) Start the engine
    10) Adjust "Trigger angle" until the timing light is at 10 degrees
    11) Set "Fixed angle" to -10
    12) Start tuning
    Does MSII code need to be told to do time-based cranking, iof you are using trigger return it will have issues trying to work out timing of trigger locations when cranking.

    (sorry answer is full of Q's, am up late and cant sleep)
    ------------------------------
    ST185 road barge / MZ11 forest barge / RA65 garage barge

  3. #3
    broken down ex guru Chief Engine Builder feral4mr2's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    thanks for your help
    Last edited by feral4mr2; 05-11-2007 at 05:58 PM.

  4. #4
    Junior Member Grease Monkey ra65's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    Quote Originally Posted by thechuckster
    no, drive the VB921 inverted - do ti the other way and you will toast that driver.

    what coil are you using? and are you sure you have 12V when cranking?

    can you hook up a spark plug to the coil HT out, rest it on the rocker cover for a good earth and see if it sparking when cranking?

    are you using the ballast resistor attached to the coil?

    have you timed the trigger wheel correctly? from the MSnSE instructions i used:


    Does MSII code need to be told to do time-based cranking, iof you are using trigger return it will have issues trying to work out timing of trigger locations when cranking.

    (sorry answer is full of Q's, am up late and cant sleep)
    Using stock 22re coil.
    Coil has power when ignition on and while cranking.
    Already tried to spark off rocker cover - thats how I know I'm not getting spark.
    Ballast resistor?...no?
    Set the timing around 10btdc. Haven't done it properly, just estimated, should still actually spark though.
    Dunno about that last question.

  5. #5
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    RA65: damn ... i'd check somehow (use a LED? to show earthing of the VB921) to check that you're getting a signal out to the VN921. Stim won't check the spark output ...

    this point of the install (the "i'm sure i've wired it up but the bloody thing wont work") is always frustating - when in doubt, recheck or re-do wiring assocaited with the problem (i did - the loom from ECU to engine bay was replaced and the 2nd loom carefully threaded thru twice).


    feral: welcome to the club! fuel-only will be easy - but seeing as you've got an ECU wired up for spark, you may as well take the plunge.

    suggestion? get a laptop, read the manuals <http://www.msextra.com/manuals/MS_Extra_Manual_Index.htm>, read them again, then research the MS forums <www.msextra.com>, get a 12V power supply so you can power up the ECU, check the MS forums for a WA person who can loan you a sim, then once you're familiar with the ECU, wire it up, tune it and do skids.

    I'd also see if you can track down and meet up with other WA users.

    fwiw: this is going on the 4AGE? that has a dizzi? use the existing 24 tooth trigger in the dizzi and the dizzi to distribute spark, check that your injectors are/are-not low-impedance, you'll also have to calibrate the ECU for the toyota temp sensors - the app to use is called EasyTherm and is on the main msefi.com site.

    Also, that MSnSE code should be updated, the current version is 29y4, see the manuals about how to update.
    ------------------------------
    ST185 road barge / MZ11 forest barge / RA65 garage barge

  6. #6
    broken down ex guru Chief Engine Builder feral4mr2's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    thanks for your help
    Last edited by feral4mr2; 05-11-2007 at 05:58 PM.

  7. #7
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    the 7mgte are low-Z - you might be able to get away with the flyback circuit on the board - i run the hi-res version of MSnSE so i have to run a resistor pack (it doesn't support control of low-Z injector that need peak-h-hold current control).

    if you want to run waste-spark coil packs you remove two opposing teeth from the 24-tooth wheel to make it a 12-1 trigger wheel (runs at 1/2 crank speed hence the duplication of the 'missing' tooth). If you're using a full dizzi, am fairly sure you just run the trigger wheel as-is - but if you're fuel only then a tacho-signal from ECU would be fine. The manual will cover it anyway.

    the megatune software remains fairly constant, it's the firmware on the ECU and the 'ini' file needed to configure megatune that changes - but if you find the code ok - the go for it. Some of the earlier Extra versions had issues with 12-1 wheels having timing stumbles at round 3.5k rpm - concensus at todays meetup in Toowoomba was that the current code fixes that.

    the difference with running two ECUs is mostly in the wiring - you can't share sensors so it complicates things.

    Are those sensors bosch units? or has the previous owner calibrated the ECU to use toyota sensors?
    ------------------------------
    ST185 road barge / MZ11 forest barge / RA65 garage barge

  8. #8
    broken down ex guru Chief Engine Builder feral4mr2's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    thank for your help
    Last edited by feral4mr2; 05-11-2007 at 05:58 PM.

  9. #9
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    Quote Originally Posted by feral4mr2
    wouldnt running a one way diode to one of the ecu's from any shared sensors solve this? (i used to use them alot in alarm installs).
    i dont think so - you're measuring resistance between the ECu and ground for temp sensors and voltage difference between 5V ref and ground for the TPS - i think you could share TPS, but not coolant/air temp. O2 sensor is also voltage so could be shared
    ------------------------------
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  10. #10
    Is a Chief Engine Builder wilbo666's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    Quote Originally Posted by thechuckster
    i dont think so - you're measuring resistance between the ECu and ground for temp sensors and voltage difference between 5V ref and ground for the TPS - i think you could share TPS, but not coolant/air temp. O2 sensor is also voltage so could be shared
    If the ECU has a high impedance input (which it should!) then you should be OK to share the sensors.

    In regards to the temp sensors work as a voltage divider, the temperature sensor forms one resistor in a voltage divider, the other resistor in the voltage divider is a pull up inside the ECU.

    As long only one ECU has the pull up for the temperature sensor then you should be fine, the ECU will just be measuring a voltage

    And you wouldn't really want to wack a diode in as you'd get a voltage drop across it, you might be able to calibrate it out tho I guess on the MS, but diodes aren't real temperature stable...

    Cheers
    Wilbo

  11. #11
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    ^^^ what he said , after all i only did journalism at uni, he did engineering

    wilbo: i think the Delco sensors will have different temp curve than the Denso units

    ... but i think that 1 ecu would be more simpler than two
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  12. #12
    MR 18RG Chief Engine Builder The Witzl's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    RA65 - do the "LED coil check" thing mentioned in the megamanual.

    This is where you hook up an LED instead of the ignition coil, and see if it flashes whilst trying to crank the engine.
    If it flashes, then you have a problem with the coil or leads.
    If it doesnt flash, then the problem is the megasquirt or the wiring (usually wiring).

    if you were in sydney i would help you out
    ...... butt scratcher?!


  13. #13
    Junior Member Grease Monkey ra65's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    Quote Originally Posted by The Witzl
    RA65 - do the "LED coil check" thing mentioned in the megamanual.

    This is where you hook up an LED instead of the ignition coil, and see if it flashes whilst trying to crank the engine.
    If it flashes, then you have a problem with the coil or leads.
    If it doesnt flash, then the problem is the megasquirt or the wiring (usually wiring).

    if you were in sydney i would help you out
    The megasquirt triggers the light on the stim. This sounds like a pretty good idea. I think I will try it tomorrow. Will at least tell me if there is a problem with the coil.

    Today I fully charged the battery, put new spark plug in number 1 and spun the dizzy over by hand. Getting erratic rpm readings on megatune like this but I am actually getting spark. Its not sparking exactly when it should so tomorrow I will try another coil and maybe wire it directly to the fuel pump relay (currently wired to stock wiring).

  14. #14
    Junior Member Too Much Toyota
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    Default Re: Megasquirt - direct coil control, no spark

    also worth checking the air-gap in the VR sensor - should be quite small otherwise at low rpm you get an erratic, messy and weak trigger signal for the ECU which will only compound other starting issues.
    ------------------------------
    ST185 road barge / MZ11 forest barge / RA65 garage barge

  15. #15
    MR 18RG Chief Engine Builder The Witzl's Avatar
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    Default Re: Megasquirt - direct coil control, no spark

    most toyota engine ervice manuals give you the recommended gap... check an online 7M-GTE or 4A-GE or 22R-E manual to give you the recommended VR gap.
    ...... butt scratcher?!


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