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Idle control using heater/ac/headlight inputs

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Idle control using heater/ac/headlight inputs

Old 01-05-2009, 06:58 PM
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Lightbulb Idle control using heater/ac/headlight inputs

I'm not crazy about the PWM closed-loop idle control in MS... it just doesn't seem to work as consistently and smoothly as the stock ECU.

From what I can tell, the oem ecu looks at the heater, A/C, and headlight inputs and adjusts the idle accordingly. I don't think it would be too hard to modify the MS code to do this. It would just require wiring in these inputs, and having the MS code adjust the idleDC (warmup mode) when these inputs are switched on. I should be able to handle the code changes myself.

Any foreseeable issues?

Discuss!
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Old 01-06-2009, 06:38 AM
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wait until keith has finished the PID control loop for closed loop idle?

That should make idle far better at coping with changes.

I'm testing an early version with just P and I and it's far better already!
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Old 02-10-2009, 05:08 PM
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Justin, I totally agree... I brought this up in the A/C FAQ thread, but it seems like most folks shy away from touching the MS code (maybe with good reason). I don't think the PID control loop alone will be enough since it will still have to react to a drop in idle rather than preempting the drop by reacting to the actual accessory coming on. An alternative solution might also be to use an ammeter to measure alternator current added to an additional "A/C is on" signal to drive a vacuum leak valve of some kind.
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Old 02-10-2009, 05:15 PM
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once suggested solution was triggering the purge valve solenoid to open with the A/C
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Old 02-10-2009, 05:19 PM
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Holy, I think you're right, but I'll probably wait until the PID code is released before I make any changes. If the PID loop works well enough, then I won't bother. But if I'm still not happy then I'll do it.
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Old 02-10-2009, 05:23 PM
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Originally Posted by Braineack View Post
once suggested solution was triggering the purge valve solenoid to open with the A/C
Yeah, I actually have my car setup to do this on your suggestion. The purge valve alone doesn't create enough of a vacuum leak to fully cover up the idle dip. I think a bigger valve is needed. Of course, and adjustable valve would be awesome... however, at the end of the day we're just reinventing the idle air valve which already has computer control

Is there a thread about Keith's plans/progress somewhere?
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Old 02-10-2009, 05:25 PM
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The only thread I know of is this one: MSx/Extra EFI • Login
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Old 02-10-2009, 05:28 PM
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Originally Posted by JustinHoMi View Post
From what I can tell, the oem ecu looks at the heater, A/C, and headlight inputs and adjusts the idle accordingly.
Incorrect. A/C, brakes, gearbox (neutral switch), clutch switch, steering switch, yes. Heater, headlights, power windows, other electrical loads, no.

Jim
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The “into to megasquirt thread” mentions that the MS3 basic has 5 inputs with built in pull up resistors - and I was just wondering why it would have so many, while the MS3Pro PnP has just 2 (with no pull ups?)
MS Labs: Plug and Play Megasquirt ECUs for ANY 90-05 Miata (NA, NB1, NB2 w/VVT, MSM), including basemaps to get you started ASAP. PM me or email or details.
For support on MS Labs ECUs: Please email, be sure to include the unit's serial number and include a datalog and your current map.
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Old 02-10-2009, 05:32 PM
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What about the blower control switch? I see there is an input to the ecu that goes low when the switch is at mid or high positions.

How sure are you that it doesn't adjust idle when the headlights are switched on? I see there is an input to the ecu for the headlight switch.
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