fourwhls needs help! 99 IAC settings - Page 3 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-03-2008, 02:05 AM   #41
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Originally Posted by FoundSoul View Post
Just a thought... when you turn it over, what are your PW when it's cranking? Not the settings, the actually PW readouts on the gauges. I want to make sure it's not reading your TPS funny and going into flood clear mode, which will cut off the injectors.
how would you tell from the gauges that it was in "flood clear"? i am having a starting issue and believe flooding may be the culprit, when i try to set mt TPS it reads 126 when i'm OFF the throttle, i checked cont b/t pins 2 + 4 and it read .5 off to 1.5 full throttle. could this be the problem?
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Old 03-03-2008, 02:08 AM   #42
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If you're in flood clear mode your PW will show as zero (0) when cranking...
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Old 03-03-2008, 02:16 AM   #43
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ok, then thats not it, they are at 3.5ish now, sound too rich for 440's?
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Old 03-03-2008, 02:19 AM   #44
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Not really, should be fine for cranking.
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Old 05-26-2010, 12:02 PM   #45
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My stock ECU is controlling idle still. We scoped the valve at 488-490 hz. So that should make it right around ~20.5 as the value you would enter.
I know this is an old thread, but I'm looking for a little more info...

What are the other values you guys are using for the '99/00 IAC control?

Idle Valve Frequency = ~20.5
Cranking (dc) = ?
Minimum (dc) = ?
Closed (dc) = ?

thanks!!
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Old 05-26-2010, 12:57 PM   #46
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with MS-I, you set the parameter by taking 10000 divided by the freq.

so, 10000/490Hz = 20.4, so 20.5 as said above is a good number.


luckily for you, first350, you have a MS-II, therefore things are a bit different.

for MS-II, you need to enter the parameter as 30.5Hz times X. so 490/30.5 = 16.

then make sure on your dashboard display you have idle PWM% shown and open advanced > idle valve test.

turn it on, and start from 0%, once you move run to home, the PWM% values should change.

each time you make a change to the PWM% value you are testing, you must change run to home or home to run, you can watch the value on your dashboard behind the window.

you need to determine the lowest PWM% that the value can react and note the RPM, and then the highest PWM% and note the RPM.

Then turn on PWM closed Loop idle.

open your "closed loop idle target RPM" set it to something like 1000RPM across the board.

open 'closed loop idle valve settings'

set the idle open/close duty % to the numbers you determined as the highest/lowest values the idle valve can lower/raise the idle with.

open 'closed loop idle PID settings'

set the RPM range in which the idle valve operates. make sure the min PID% number is just slightly above the min closed DC% number so the valve cannot b e adjust lower than it's range.

make sure the P I D settings are all zeroed out.



burn all change and cycle power to the MS.

your idle should now be pretty high. so start increasing integral Gain % until the target of 1000RPM is achieved. Next increase Proportional gain% until there is oscillation, then then back the number back a little bit.


you should now have good idle.
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Old 05-26-2010, 01:44 PM   #47
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Can you actually get good close loop control with a frequency of 490Hz? That only gives you a 6.25% resolution on the duty cycle. I think that you'll still get oscillations with perfectly set PID parameters simply due to the fact that it's a very coarse resolution.

Jean
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Old 05-26-2010, 02:10 PM   #48
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In my experience with it, the PWM% number hardly needs to deviate once it settles down from the dashpot setting; once it's idling under PID control the pwm% hardly changes unless some random load is on the motor.

I've run my 1.6L IACV at 390Hz before and it hardly oscillates, only when I would switch on the A/C and it was trying to recover, settled within a few seconds. But I had improperly setup the parameters, but I really don't have any experience tuning a '99 valve, so you may still have a little. Right now my idle is better than with the stock ECU controlling it in a parallel configuration.

Tuning idle AFRs at all loads is key to win as well.


also, fwiw, I have to run inverted polarity...
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Old 05-26-2010, 05:10 PM   #49
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I struggle with my idle, though it's a lot better since the sequential code was fixed...

I don't think my overly large (600cc) old school (poor - low PW - spray pattern) injectors help, though I keep thinking I may have thedead time wrong for them

Agreed though that if you can get the PWM to stay static the idle is absolutely blob on, you just need closed loop there to compensate for temp changes, not to actually vary the idle valve to regulate an rpm range. getting it to do that is the tricky bit
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Old 05-26-2010, 06:05 PM   #50
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I get perfect idle 750-850 rpm with/without ac, fan, headlights. I'm running sequential 750cc injectors, 1.8l, ..........check signature



I also read over the ms3 closed loop idle documentation and spent about half an hour adjusting parameters to set this. I am not using a 99 valve, so this could all be useless.
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Old 05-26-2010, 09:19 PM   #51
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I get perfect idle 750-850 rpm with/without ac, fan, headlights. I'm running sequential 750cc injectors, 1.8l, ..........check signature



I also read over the ms3 closed loop idle documentation and spent about half an hour adjusting parameters to set this. I am not using a 99 valve, so this could all be useless.
But you're also running your valve at 30.5Hz which means you have a 0.4% resolution which is 16 times better than running at 488Hz. That alone will make close loop work much better because the valve can be controlled precisely for any situation.

With a 6.25% resolution, if the code decides it needs just a bit more or just a bit less PWM duty cycle, it will either stay where it is or jump by a full 6.25% which will make a big difference. You can probably find a stable position and the duty cycle will not change (because it can't due to the coarse setting) but if you try to set your idle just between 2 steps then you're screwed and you'll have wild oscillations which no amount of PID parameters tuning will be able to get rid of.

I'm not familiar with this specific setup so this may just be a theoretical situation which is of no consequence because it won't happen. However, it is something to keep in mind if a stable idle can't be reached because there will be differences in each setup and it might be the reason someone is struggling with it while others aren't.

Jean
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Old 05-27-2010, 11:28 AM   #52
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you can see where I trigger the a/c and all is still well in the universe.
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Old 05-28-2010, 04:16 PM   #53
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I tried setting the freq parameter (30.5Hz times X.) to 16...but tuner studio pops up a window and says 15 is the max. With it set at 15, the idle would ossiclate a few times before becoming steady. I'm not too concerned with this...but will mess w/ the setting more.

Also - When I turn the ignition to ON (but the car is off), the IAC "hummmsss"...I confirmed that it's the IAC by unplugging it and the sound went away. Is this correct? I don't recall hearing the IAC w/ the OEM ECU.

Thanks!
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Old 09-23-2010, 03:44 PM   #54
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Starting to play with closed loop idle as well but I'm not sure how to set 'Idle Open Duty'.
When I raise the steps in the idle valve test window, my idle rpm just goes up and up until steps are 100%. At that point I'm idling at 5K rpm. Does this mean my Idle Open Duty is 100%?
Or should I set Idle Open Duty to a value that I think is the maximum that my PWM should go. IOW, the duty needed to reach say 1500 rpm or so?

Idle valve closed duty: my rpms never drop under 850rpm with the sweet spot around 10% PWM (anything lower doesn't lower rpms). Am I right that Min Duty for PID can be set to the same value? (in my case 10% to reach 850 rpm)?
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Old 09-23-2010, 03:51 PM   #55
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sounds like it. anything below 25% duty on my valve does nothing, there is no reaction. anything above 70% is the same, i hit something like 4K and it wont go higher. So that's the window the valve operates.

you might want to manually close the bypass screw a little, but i guess that isn't bad as is.


what your timing and AFRs as those can easily cause the idle speed to get upset, im going to be using table switching for my ignition table with A/C activation now.
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Old 09-23-2010, 05:06 PM   #56
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Here is what I did to find my values. It may be wrong. It is not the way that was recommended, or maybe it is and I just didn't understand. It seems to work. Datalog while driving and then select PWM duty and look at the min/max values while driving. My min value was 23.2 and my max value was 43.0. This was during about 30min of driving under different load conditions. I input these as my min and max duty. I then looked at what rpm these values seem to correspond. 750-850 for min rpm and 1300rpm for max rpm. I did a little research on the valve, and the 1300rpm max seems to fall in line with how the IAC is supposed to perform.
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Old 09-23-2010, 05:10 PM   #57
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pretty much the values I'm using.
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Old 09-25-2010, 12:07 PM   #58
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Been playing with it for a couple of days and this stuff is just amazing. Rock solid idle @ 850 rpm and 14.7 afr.
Turning on headlights gives an ever so slight dip to just under 800rpm thanks to idle advance. Cool stuff.
Guess I'll have to do EAE now as well.

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Old 09-25-2010, 12:26 PM   #59
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PLease post your settings Frank!
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Old 09-25-2010, 01:19 PM   #60
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