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Old 04-27-2007, 01:43 AM   #1
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Default Idle Tuning

I've been trying to get a good clean closed loop idle and it seems to be impossible. I've tried just about every frequency possible with all different kinds of cranking and minimum dc values.
Is there a magic set of numbers because i've gone through about 5 different MSQs that have closed loop setup as default idle. So to no avail am I getting any closer to having closed loop idle working. I've tried warm up only and that doesn't work well either. So i'm pretty much lost as to what I need to do in order to get a good idle. I have the diode installed and am just flat out lost.

It will sometimes sit around 500 rpm and bounce around while running rough as heck.
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Old 04-27-2007, 01:50 AM   #2
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i gave up pretty quickly, since open loop worked just fine.
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Old 04-27-2007, 02:36 AM   #3
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I can't seem to get the MS to oscillate the AFs as regularly as the stock ECU causing for a rough idle which works sometimes but is unpredictable ... so I settled for open loop.
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Old 04-27-2007, 10:27 AM   #4
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I haven't messed with open loop at all. I'll do that tonight if I get a chance.
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Old 04-27-2007, 12:41 PM   #5
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Give it a shot, my BP seems to like idling in the 12-13 A/F range if I want it to be smooth. Not ideal but I hate a rough idle.
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Old 04-27-2007, 02:14 PM   #6
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My idle is butterz at 14.7 AFR with an 900rpm idle.
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Old 04-27-2007, 02:15 PM   #7
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Don't brag *******.

Closed loop?
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Old 04-27-2007, 02:17 PM   #8
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i dont believe so.
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Old 04-27-2007, 02:33 PM   #9
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Scott still has his stock ECU doing idle I believe. That is why his idle is perfect.
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Old 04-27-2007, 02:36 PM   #10
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Makes sense.
That won't work with bigger injectors though right such as 550s.
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Old 04-27-2007, 02:46 PM   #11
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we'll see i have 460s on the way...im idling 305s now, I think Brian was idling 550s with his without problems.
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Old 04-27-2007, 02:53 PM   #12
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it's also because he's sharing sensors witht the stock ecu. i had to do idle control because my CAS has its own MS-only harness now.
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Old 04-27-2007, 03:46 PM   #13
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Seeing how my stock ECU still see's its own tach signal via the crankpositon sensor and MS has it's own CAS, do I need to even worry about idle then? I guess i don't really know how the IAC solenoid works.
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Old 04-27-2007, 04:22 PM   #14
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Quote:
Originally Posted by cjernigan View Post
Makes sense.
That won't work with bigger injectors though right such as 550s.


Why not? I'm running 460s and have a smooth stock-ecu controlled idle. To do so the ECU needs CLT and rpm, which are still connected to the stock ecu. No AFM or IAT needed.
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Old 04-27-2007, 04:32 PM   #15
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See that's where me not understanding what the hell is going on with the idle control comes in. Like i said I have not much of a clue. I'm not going to screw with idle anymore than what a PITA. Get the clutch fixed and put in the 550s. Looks like i've got a tiny bit of work ahead of me.
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Old 04-27-2007, 06:36 PM   #16
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How are you guys controlling the injectors at idle with the stock ECU and then controlling them with the MS off idle? Unless you are using something like Emanage.

The car will hold an idle RPM within 20-40 RPM very well even without an IAC there at all. The A/F ratio control is the problem with the MS
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Old 04-27-2007, 06:41 PM   #17
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I didn't have much luck with the Warmup Only idle settings today. I'll spend more time with it later.
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Old 04-27-2007, 08:35 PM   #18
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Quote:
Originally Posted by Lex View Post
How are you guys controlling the injectors at idle with the stock ECU and then controlling them with the MS off idle? Unless you are using something like Emanage.
Not the case. The only thing the stock ecu controls is idle speed and the AC. Fuel is a small part of the idle equation, you'll find that ignition timing is much more influential. For example, to get a stockish idle I had to run 10-12 degrees timing. At 14 degrees the idle would be unstable. On the other hand, it seems to idle anywhere from 13 to 15 afr with little care.
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Old 04-27-2007, 08:45 PM   #19
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Quote:
Originally Posted by mschlang View Post
Not the case. The only thing the stock ecu controls is idle speed and the AC. Fuel is a small part of the idle equation, you'll find that ignition timing is much more influential. For example, to get a stockish idle I had to run 10-12 degrees timing. At 14 degrees the idle would be unstable. On the other hand, it seems to idle anywhere from 13 to 15 afr with little care.
I have a 11 timing idle and tested many settings out ... still couldn't get it to be smooth without it being rich.
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Old 04-28-2007, 01:12 AM   #20
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What is your injection PW at idle? I'm around 1.9 ms, if your idle PW is too low it may be causing your lack of idle AFR control.

http://www.megamanual.com/v22manual/mtune.htm#idlepw
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