Anotha MS3z that will doez the VVTz - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-08-2011, 06:33 PM   #21
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I have a loud stereo.

I do have some PWM converter boards but... it idles fine so...
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Old 03-09-2011, 02:24 PM   #22
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To answer my own question: I reduced the idle valve frequency from the MS3 to 50Hz and hooked it up to my own expansion board that ups the frequency to 490Hz: It idles better now and doesn't hum as loud.
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Old 03-11-2011, 11:31 AM   #23
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We can probably check to see if we can add something closer to 500 Hz.

Ken
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Old 03-21-2011, 12:05 PM   #24
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Now that it's been on the car for a bit what's your impression?
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Old 03-21-2011, 12:12 PM   #25
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It feels smoother than the MS2, it doesn't having a random misfiring issue that the MS2 has (at least I haven't felt it for the past week), I like that it doesn't stumble when I save changes, the number of available inputs/outputs is AWESOME. It required a LOT more fuel than the MS2, around 50% in most areas (I idle at 40 in the MS2, 61 in the MS3), and I still haven't nailed down the cranking fueling - it doesn't start as nice as the MS2, but that's obviously in the tuning, and when I want to leave I'm usually in a hurry.
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Old 03-21-2011, 12:13 PM   #26
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The misfire thing is funny. My MS3 missed where the MS2 didn't. Going seq. spark solved that however.

I noticed a similar thing with my fuel maps so I altered the req_fuel value instead of rescaling/retuning the fuel map.
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Old 03-21-2011, 03:25 PM   #27
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Hey Dimitris,

Any chance you could scope the VVT solenoid's current draw and flyback effects?
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Old 03-21-2011, 05:46 PM   #28
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Are you looking for something in particular?
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Old 03-21-2011, 06:14 PM   #29
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yes in fact!

after I started using VVT, the Q3 (upper right of schematic below) transistor started to get reeeeeally hot and screwing with all my PWM outputs on the expander board.



I know you're not using that board but I'm curious if there's something about the VVT solenoid that causes problems with that circuit.

Temporary solution was a diode between VVT and +12.

Potential more universal solution is changing the 32V zener to a 22V zener.

I'm just a user so I only have a marginal grasp on cause and effect here. As I understand it, there is something about the solenoid that's forcing that transistor to dissipate a lot of power (so much that it heats up and discolors) but only with the VVT-compatible firmware.

Big ol shot of Q3:

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Old 03-21-2011, 06:32 PM   #30
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I am, in fact, using the MS3X. I can easily scope the voltage, but not the current.
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Old 03-21-2011, 06:57 PM   #31
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oh!

I thought you made yourself a superior board.

You could measure the voltage across the resistor R69 and infer some things about current, couldn't you?
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Old 03-21-2011, 07:27 PM   #32
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Quote:
Originally Posted by y8s View Post
I thought you made yourself a superior board.
Not yet, young grasshoper.

The zener is ok at 36V, it shouldn't be a problem. I will have a look with the scope if I find some time tomorrow.
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