"roflcopter" (roflroflroflcopter)
04/10/2014 at 14:47 • Filed to: None
2
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"roflcopter" (roflroflroflcopter)
04/10/2014 at 14:47 • Filed to: None | 2
| 7 |
Now I know some of you guys have messed around with Megasquirt before, and now I'm calling on the masters to help get my buddy's car running. We've been working on his Datsun 280 for the last two months or so and everything is mechanically done, the last step was engine management. After 4 days of trying things and fixing little issues we still can't get the thing to idle. Anyone want to chime in with ideas? (Details after the jump)
His Setup:
L28E+T
N/A Intake Manifold
259cc/min Turbo Fuel Injectors
Intercooled
The system he got is a MS1 v2.2 and I'm pretty sure we have the tune pretty close, but some verification on numbers looking close to correct would be awesome. We have a Req_fuel of 12.0, 6 injectors fired simultaneously for 2 injections per cycle, they are low-impedance, which puts us as a PWM Current Max of 30% with a PWM Duty Cycle of 1.0ms. The injector opening time is set to 1.0ms as well and our cranking pulse widths follow the 88% to 23% figure prescribed by the Megamanual and it does try to kick just fine(we tried setting them all the same to different values and found between 4.5ms and 5.0ms to work fine which is what the ambient temp range is in that table with proper 88% to 23% scaling). The problem is that it won't idle up once it fires. Black smoke when it dies out and every now and then it will 'idle' at somewhere between 300-500rpm although it sounds like it's missing and if you let off/roll on the throttle it dies immediately. Our After Start Enrichment is set to 250 cycles and we've played with it everywhere between 100% and 180% to no avail, as well as the Warm Up Enrichment in the 100% to 140% range.
The VE Table looks proper, in the 50-65% range for most of the idle areas(which is what we are worried about right now. The plugs are pretty fouled after trying all of this for a few days so first thing today will be to clean them and get all that sorted out. We're 100% getting spark on all 6 plugs, fuel injectors are clicking, none of them look different from the rest, we're getting clean and clear crank signal with proper RPM we think. Any other ideas?
fixthefernback
> roflcopter
04/10/2014 at 15:01 |
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Does the MS1 have the proper add-on board to control low-impedance injectors?
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roflcopter
> fixthefernback
04/10/2014 at 15:04 |
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He's the one that put all of that together, but from my reading and from what he said it seems that the proper flyback circuit is all that is required and you use the PWM Current Limit and PWM Time variables to keep from burning up the injectors.
RamblinRover Luxury-Yacht
> roflcopter
04/10/2014 at 15:11 |
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Sorry not to help, but I'm going to attend this conversation raptly, as I'm going in the Megasquirt direction with a V8 probably some time this year.
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fixthefernback
> roflcopter
04/10/2014 at 15:11 |
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I would try sucking gently on the MAP line to make sure the MAP sensor is working and isn't getting a noisy signal or pinched. I had issues with my Miata when the MAP sensor line got pinched.
Sounds like its too rich. Could be caused by the fuel table tuning, or a false MAP sensor reading. If there's any chance that it could have held an injector open while flashing firmware, doing any troubleshooting, or having hardware issues check to make sure the intake manifold isn't flooded with fuel (happened to me. even after fixing the hardware issue it took forever for the fuel to evaporate and burn off.)
Is it a fuel only install or fuel/spark? Now would be a good time to check timing regardless. Good luck!
deekster_caddy
> roflcopter
04/10/2014 at 15:17 |
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Too much fuel pressure? (will make it overly rich, which sounds like your problem) All the other specs you listed assumes the fuel pressure is where it should be.
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roflcopter
> fixthefernback
04/10/2014 at 22:16 |
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The MAP was properly reporting things(as fas as what I would expect), and it definitely sounds like too rich, except that more throttle makes it die. The setup is doing fuel and spark, but there is a distributor involved and we checked that all 6 plugs were firing and that the timing was right around 10 degrees btdc.
He ordered a different optical sensor for the distributor on the off chance we're getting bad RPM readings. We'll see tomorrow when it gets here.
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roflcopter
> deekster_caddy
04/10/2014 at 22:16 |
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We're sitting right at 40psi after turning the key on, and then it drops into the 30's while cranking. Seems normal enough to me.