ISC on my MS3 works backwards !!!?? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-01-2013, 04:58 PM   #1
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Red face ISC on my MS3 works backwards !!!??

Ok, I upgraded to an MS3 on my 91 with gredy turbo. My friend wired it for sequential and did some fine tuning but could not get closed loop to work right.

The car runs great but I started looking into the closed loop issue myself.

Short story long.... When I use the test facility in TS, the idle speed increases when I decrease PW !!!!!

Am I doing something stupid ?
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Old 08-01-2013, 05:37 PM   #2
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Startup/Idle -> Idle control -> Valve mode: Normal, 0% = Off (You probably have it set to "Inverted, 100% = Off").
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Old 08-01-2013, 05:41 PM   #3
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Quote:
Originally Posted by Reverant View Post
Startup/Idle -> Idle control -> Valve mode: Normal, 0% = Off (You probably have it set to "Inverted, 100% = Off").
Thank you brotha !!!

That would be great if that's all it is.. It has been driving me nuts!!
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Old 08-02-2013, 07:09 PM   #4
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Wow!! Big can of worms!!!

Reversing the function in the program does not seem to do anything with the car running or in the test mode.

Now this is interesting.
There seems to be a portion in the middle of the PW values range where the RPMs reverse – the RPMs do go up when you peg the valve at 89 and down at something like 22 but then you hit something like 56 and it drops further.
It is as if there was an over center position on the valve where it gets wonky in the middle of the range RPM wise.
I don’t know if ignition timing or something is “fighting” something else or if it is mechanical.

Mechanically; I can see the valve rotate incrementally as I increase the PW. Both valves behave the same but the lap top is not like a switch – sometimes it does not act the command or my 2 ISC valves are hosed (?)

Tired
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Old 08-17-2013, 08:18 PM   #5
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Adding a diode to the ISC connector across the wires seems to bring the range to where it should be (cathode to the white and red wire)....
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