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Thread: Megasquirt users thread to discuss all things Squirty

  1. #631
    Junior Member Conversion King timbosaurus's Avatar
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    Default Re: Megasquirt users thread to discuss all things Squirty

    Quote Originally Posted by Ken_T View Post
    Thanks for that timbo. I'd half heard that ms units don't like noise. I got mine running on the CA and it just hates running. Afr's look fine, timing is confirmed with a light and it should be idling just fine. I've put a backward ramp on the timing and fuelling to try and stabilise idle but it's misfire city and idles like shit. Using just about the same settings on the vipec makes it run better and has a much stronger sounding note but still has plenty of misfires. It runs fine on stock ECU though.

    I'm thinking the issue stems from having the ignitor in cabin near the ecu and all the noise it generates. I'm going to ditch the ignitor and switch to some denso coils to see if it goes away. Do you think this is an issue?
    Ken, the problem with any aftermarket ECU is that there are more configurable things, so more opportunity for mistakes. Megasquirt takes this configuration to another level, and I guess that's why it's a love/hate ECU.

    If your AFR's and timing are good (I aim to idle at around 13:1 AFR and 10 deg timing), but your car still runs like ass, then it's definitely possible that the input signal is not stable, or the firing order is out(remember that you're only checking no.1 with the timing light), or the dwell is not setup correctly. How stable was your rpm readout in Tunerstudio? any spikes?

    What sort of hardware do you use on the cam/crank trigger? VR, hall, optical? Have you looked at the composite logger to see if there are any missed/extra pulses that shouldn't be there?

    I've never had a problem with radiated EMC into the MS itself (eg: from the ignition drivers or spark leads or coils) when I do the fundamentals right. It's not to say it doesn't happen, I've just been fortunate enough to not have the issue.

    When I say fundamentals, i mean:
    • Only use "resistor" plugs (eg: NGK "R")
    • Only use trustworthy leads. I don't recommend a brand, but I do recommend tightly wound spiral core wires. Never use solid core wires on an ECU controlled car. Read this link, then read it again, then for a third time. http://www.magnecor.com/magnecor1/truth.htm
    • Keep your crank/cam signal wiring basic. I aim to have a single unbroken length of high-quality twisted and shielded temp rated cable (I use mil-spec tefzal cable - http://www.skygeek.com/m27500-22tg4t14.html), quality connectors on either end. I still haven't had a problem putting it inside the main loom with the injectors/coil/etc wires.
    • Ground the ECU per the instructions, all earths separately lead to one ground point on the block, and a heavy gauge wire from there to the body. It annoys me to having to package 5-10 earth wires in my harnesses, but enough people have had dramas for me to not take the risk.
      The rest, like good solder joints, good crimps, correct gauge wire etc just goes without saying


    I'm not sure which ignitor you use, but it *shouldn't* be a problem. On 90% of megasquirts, the ignitor (VB921 chip) is fitted inside the ECU enclosure!

    If you let me know what you've got on a CA (one coil and a dizzy, 2 coils in wasted spark, four COP units with or with out built in ignitors), I could tell you how I would set it up (for what it's worth). I'm a minimilist, and nothing bugs me more than having 3 different systems that could be replaced with one. So if I can get away with ditching some unnecessary parts, I will.
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  2. #632
    Junior Member Domestic Engineer ill-minded's Avatar
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    Default Re: Megasquirt users thread to discuss all things Squirty

    Timbo, I think you may have just answered why my Daihatsu is such a nightmare to start. At the very least, you've given me food for thought. I get sync loss issues when cranking, which makes it really frustrating when you need to be somewhere. The trigger wheel is a cam speed 3 tooth + one extra reset tooth like so. I'm also running a JBperf conditioner, and given the low tooth count and low RPM when cranking, it seems possible that this is part of the issue. On the flipside though, I've already got a shunt resistor (330R from memory) installed, so I might fiddle around with some different resistor values or a variable and see if things improve. Oddly enough, once it's up and running, there's no issues with sync loss at all.

    Pity I can't test anything at the moment until I've got the exhaust finished.

  3. #633
    Junior Member Automotive Encyclopaedia
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    Default Re: Megasquirt users thread to discuss all things Squirty

    Theres some good info for me too. Thanks timbo

  4. #634
    Junior Member Grease Monkey
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    Default Re: Megasquirt users thread to discuss all things Squirty

    Quote Originally Posted by timbosaurus View Post
    Ken, the problem with any aftermarket ECU is that there are more configurable things, so more opportunity for mistakes. Megasquirt takes this configuration to another level, and I guess that's why it's a love/hate ECU.

    If your AFR's and timing are good (I aim to idle at around 13:1 AFR and 10 deg timing), but your car still runs like ass, then it's definitely possible that the input signal is not stable, or the firing order is out(remember that you're only checking no.1 with the timing light), or the dwell is not setup correctly. How stable was your rpm readout in Tunerstudio? any spikes? I've had the idle timing anywhere from 6 to 16 without much luck. idles happier at less than more. Can't "check" AFR's as I think I killed the wideband sensor, got a new one coming. Says 11.4ish at idle on the stock ECU so I try and get the vipec and ms to about the same. The input is from an optical sensor which has no noise that I can see on my little pocket oscilloscope. When the car's running, nothing shows up in sync error logger, the sync flag is always at 1 on the compsite log. Checked firing order using the output test mode. I've moved the dwell from 2ms up to 5ms and no difference in idle quality. No spikes in tunerstudio on the rpm needle.

    What sort of hardware do you use on the cam/crank trigger? VR, hall, optical? Have you looked at the composite logger to see if there are any missed/extra pulses that shouldn't be there? The "low res" goes in through the v3 mainboard configured in VRIN and VROUTINV as per Nissan CAS instruction. Pots have been set accordingly and the oscilloscope looks good when cranking. The "high res" signal goes straight into PT4 or the MS3X card as per Nissan CAS instructions.

    I've never had a problem with radiated EMC into the MS itself (eg: from the ignition drivers or spark leads or coils) when I do the fundamentals right. It's not to say it doesn't happen, I've just been fortunate enough to not have the issue. I noticed there were tiny little sparks between the coil mounting bolts and the coil when not bolted down. Tightened them down and the idle got better. I read on the MS forums that SR coils cause a stutter with MS and the fix is ditching the ignitor, so I'm trying that.

    When I say fundamentals, i mean:
    • Only use "resistor" plugs (eg: NGK "R") Using BCPR6ES
    • Only use trustworthy leads. I don't recommend a brand, but I do recommend tightly wound spiral core wires. Never use solid core wires on an ECU controlled car. Read this link, then read it again, then for a third time. http://www.magnecor.com/magnecor1/truth.htm No plug wires here.
    • Keep your crank/cam signal wiring basic. I aim to have a single unbroken length of high-quality twisted and shielded temp rated cable (I use mil-spec tefzal cable - http://www.skygeek.com/m27500-22tg4t14.html), quality connectors on either end. I still haven't had a problem putting it inside the main loom with the injectors/coil/etc wires. Using standard harness with patch harness so the PT4 wire being uninsulated could be an issue
    • Ground the ECU per the instructions, all earths separately lead to one ground point on the block, and a heavy gauge wire from there to the body. It annoys me to having to package 5-10 earth wires in my harnesses, but enough people have had dramas for me to not take the risk. This is not something I'm doing. MS has more earths than Nissan loom so I've connected a few together at the patch harness.
      The rest, like good solder joints, good crimps, correct gauge wire etc just goes without saying


    I'm not sure which ignitor you use, but it *shouldn't* be a problem. On 90% of megasquirts, the ignitor (VB921 chip) is fitted inside the ECU enclosure!

    If you let me know what you've got on a CA (one coil and a dizzy, 2 coils in wasted spark, four COP units with or with out built in ignitors), I could tell you how I would set it up (for what it's worth). I'm a minimilist, and nothing bugs me more than having 3 different systems that could be replaced with one. So if I can get away with ditching some unnecessary parts, I will. CA is COP with external ignitor located on the strut tower which I relocated to in cabin. Going to make a jumper and switch to denso coils when connectors arrive.
    The funny thing is, both the MS and vipec don't run perfectly. I've set both of them up as similar as I can and the vipec is outperforming the MS3 at this stage.

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