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Old 01-20-2010, 05:19 PM   #1
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Default Idle Control Talk (From VE Live Thread)

With closed loop PID idle, everything is really ok except for two or three things:

1) The algorithm can't catch the A/C when you are idling. Too much load, too sudden. The idle will drop by 200-300rpm before the valve opens some more, it will then overshoot by 150rpm and then rest to the final target RPM. Btw my target idle once warmed up is 1000rpm, not 800rpm. I'm going to add an idle-up air valve to remedy this.
2) When you coast down, the algorithm will try to settle somewhat higher than your target RPM (ie with 1000rpm target, that's about 1400rpm) for a couple of seconds then slowly drop down to your target RPM. Annoying, but the car never stalls that way.
3) When you first start the car, it will first idle at 2-2.5K rpm for a couple of seconds and then drop to 1400rpm (my target when CLT ~= 5C). Probably due to 2).

Jim
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Old 01-20-2010, 05:26 PM   #2
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Quote:
Originally Posted by Reverant View Post
With closed loop PID idle, everything is really ok except for two or three things:

1) The algorithm can't catch the A/C when you are idling. Too much load, too sudden. The idle will drop by 200-300rpm before the valve opens some more, it will then overshoot by 150rpm and then rest to the final target RPM. Btw my target idle once warmed up is 1000rpm, not 800rpm. I'm going to add an idle-up air valve to remedy this.
2) When you coast down, the algorithm will try to settle somewhat higher than your target RPM (ie with 1000rpm target, that's about 1400rpm) for a couple of seconds then slowly drop down to your target RPM. Annoying, but the car never stalls that way.
3) When you first start the car, it will first idle at 2-2.5K rpm for a couple of seconds and then drop to 1400rpm (my target when CLT ~= 5C). Probably due to 2).

Jim
Idle has been my pet peeve with MS
I've screwed with everything that I can screw with and driven DIY people nuts. Even installed a VTPS.

I don't mind the idle moving around, having the motor idle fast etc but the idle drooping between shifts drives me nuts cause the car seems to jerk when you let out the gas between shifts.
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Old 01-20-2010, 05:31 PM   #3
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Quote:
Originally Posted by Reverant View Post
With closed loop PID idle, everything is really ok except for two or three things:

1) The algorithm can't catch the A/C when you are idling. Too much load, too sudden. The idle will drop by 200-300rpm before the valve opens some more, it will then overshoot by 150rpm and then rest to the final target RPM. Btw my target idle once warmed up is 1000rpm, not 800rpm. I'm going to add an idle-up air valve to remedy this.
2) When you coast down, the algorithm will try to settle somewhat higher than your target RPM (ie with 1000rpm target, that's about 1400rpm) for a couple of seconds then slowly drop down to your target RPM. Annoying, but the car never stalls that way.
3) When you first start the car, it will first idle at 2-2.5K rpm for a couple of seconds and then drop to 1400rpm (my target when CLT ~= 5C). Probably due to 2).

Jim

Thought about opening the purge solenoid when you trigger a/c? This should make a small vacuum leak when it's on, so it might be a big droop.

Heck, my stock does that.

Lame.
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Old 01-20-2010, 05:35 PM   #4
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What the hell is with all of you guys having such big problems with idle? I don't run any sort of idle control and my car is ruck solid @900 rpm regardless of load. It idles so well that when JayL saw it he was like "Damn, your car idles really smoothly".
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Old 01-20-2010, 05:50 PM   #5
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Originally Posted by Jeff_Ciesielski View Post
What the hell is with all of you guys having such big problems with idle? I don't run any sort of idle control and my car is ruck solid @900 rpm regardless of load. It idles so well that when JayL saw it he was like "Damn, your car idles really smoothly".
With the lights on too? If I let mine idle at 900 it would probably do well with the lights on. Mine idles at about 800 rpm with lights off and about 550 to 600 with lights on. It doesn't stall with the lights on, but I always think it might.
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Old 01-20-2010, 05:51 PM   #6
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Quote:
Originally Posted by Reverant View Post
With closed loop PID idle, everything is really ok except for two or three things:

1) The algorithm can't catch the A/C when you are idling. Too much load, too sudden. The idle will drop by 200-300rpm before the valve opens some more, it will then overshoot by 150rpm and then rest to the final target RPM. Btw my target idle once warmed up is 1000rpm, not 800rpm. I'm going to add an idle-up air valve to remedy this.
2) When you coast down, the algorithm will try to settle somewhat higher than your target RPM (ie with 1000rpm target, that's about 1400rpm) for a couple of seconds then slowly drop down to your target RPM. Annoying, but the car never stalls that way.
3) When you first start the car, it will first idle at 2-2.5K rpm for a couple of seconds and then drop to 1400rpm (my target when CLT ~= 5C). Probably due to 2).

Jim
I posted on MSExtra, tuning tips from Ken may well help?

Megasquirt MSEXTRA and MS3EFI • View topic - Advice on tuning Close loop idle

RE: point 3, that's easily fixed, alter the PWM Cranking Duty table a bit, and then reduce the crank taper to PID setting lower, Mine cranks and catches to around 1500rpm then drops to 1300rpm.

I'll try a higer target, but I'd really like an 850rpm idle like stock
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Old 01-20-2010, 05:54 PM   #7
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Originally Posted by poobs View Post
Idle has been my pet peeve with MS
I've screwed with everything that I can screw with and driven DIY people nuts. Even installed a VTPS.

I don't mind the idle moving around, having the motor idle fast etc but the idle drooping between shifts drives me nuts cause the car seems to jerk when you let out the gas between shifts.
LOL wut.

How can idle be dropping inbetween changing gear, the two things are not related.

If you don't like the revs dropping when you depress the clutch fit a heavier flywheel.

Jerking when letting off the accelerator is deceleration enrichment, look it up in the MM
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Old 01-20-2010, 05:55 PM   #8
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Quote:
Originally Posted by Jeff_Ciesielski View Post
What the hell is with all of you guys having such big problems with idle? I don't run any sort of idle control and my car is ruck solid @900 rpm regardless of load. It idles so well that when JayL saw it he was like "Damn, your car idles really smoothly".
What spark angle you run at idle? It doesn't change with temperature? I'm guessing no A/C or any of that fancy stuff.
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Old 01-20-2010, 06:03 PM   #9
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Quote:
Originally Posted by Jeff_Ciesielski View Post
What the hell is with all of you guys having such big problems with idle? I don't run any sort of idle control and my car is ruck solid @900 rpm regardless of load. It idles so well that when JayL saw it he was like "Damn, your car idles really smoothly".
Meaning you aren't using your idle valve? I have mine blocked off. I shoved a lugnut in the IAC hose

So just hooked up the boost controller. Its a lot more fun at 12psi again but I think I need to get a different spring in the MBC, I think its too stiff.

Also my upper Vband is leaking again on my downpipe :(:(:( I think i'm going to end up removing it completely. It must just be warped beyond repair at this point. Oh well.
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Old 01-20-2010, 06:06 PM   #10
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14-15* at idle. No ac/ps. Idles right at 800-900 rpm lights on or off, and is pretty temperature indifferent. I haven't touched my idle screw at all since before winter started. My idle AFR is right around 13.8-14.2. Now if I back it down to 14.7 like I have it right now for emissions, it gets a little choppier, but it doesn't even come close to stalling (which I think is in part due to my use of DSM 450cc injectors, which are slow as hell).
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Old 01-21-2010, 02:12 AM   #11
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Quote:
Originally Posted by Jeff_Ciesielski View Post
What the hell is with all of you guys having such big problems with idle? I don't run any sort of idle control and my car is ruck solid @900 rpm regardless of load. It idles so well that when JayL saw it he was like "Damn, your car idles really smoothly".
My car also idles very smoothly, except for when you trigger the A/C. Only then does engine drop the revs, sometimes 250-300, sometimes only 100rpm which is "almost perfect". Damned perfectionists.

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Old 01-21-2010, 04:06 AM   #12
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Can we see your settings Reverant?
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Old 01-21-2010, 07:23 AM   #13
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Can we see your settings Reverant?
Here you go.

Jim
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Old 01-21-2010, 07:27 AM   #14
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Many thanks Jim, that helps a lot. I've not yet worked out my rpm with valve open and closed and the corresponding DC% numbers I think that's why I'm struggling, plus the bleed valve in the TB is fully shut.

I am at a P value of 200 yet stiil no oscillation. I think once the above are nailled tuning the PID loop will be more successful.
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Old 01-21-2010, 09:29 AM   #15
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Do you have the 96 or the 01 idle valve?

Jim
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Old 01-21-2010, 09:54 AM   #16
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Do you have the 96 or the 01 idle valve?

Jim
I fitted the 96 TB and Idle valve to my 2001 motor, mainly because it was getting late on Sunday and I was running out of time, but also because I didn't want to cut the harness up, the 2001 TPS is a 3 pin affair and doesn't fit my 4pin plug (obviously), and the IAC valve is still a 2 pin but a different shame (damn you Mazda!)

I realise your setting likely won't be the same in a lot of areas, but it's helped a lot just knowing that a 'P' term of 200 isn't right and a much lowewr term can be used - abeit with a different valve.
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Old 01-21-2010, 11:24 AM   #17
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Someone try these settings.



These are common settings from msextra. Weather is poor here today otherwise I would try. I'm pimping the toyota echo today.

2 Idle Control
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Old 01-21-2010, 02:23 PM   #18
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A word to the warning: I'm using Jean's PWM multiplier board to get to ~500Hz (488Hz) without losing any precision. That also means that my signal is inverted (0%=on, 100%=off). So take these settings with a grain of salt.

Jim
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Old 01-21-2010, 07:46 PM   #19
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I'm still trying to smooth out my idle before I go on to use the new sliced bread version of TS

I am trying to address idle fluctuations, idle sag between shifts.

I changed the following as per reccomendations from DIY via email.

Min dc from 21 to 22 ( to help with idle droop )

Fast idle "lower" 130 to 120

Slow idle ( upper) 169 changed to 140 RPM

Slow (warm) idle raised to 1000

VTPS theshold ADC from 150 to 10

Idle Activation 500 changed to 250

Dashpot settle time from 47 to 80

Dead band range 130 changed to 50

Fast recovery RPM 15 changed to 5

Slow recovery RPM 100 changed to 75

I would like to know if any of yous fudged around with the above issues and settings and what yous did.

Not really sure what most of these do or if I am moving them in the right direction

Thanks
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Old 01-21-2010, 10:38 PM   #20
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Can some of you who don't have or have fixed the idle issues comment on my settings ?

I would like to fix my droopy idle issue and idle droop between shifts before I start playing with the new TS

I changed the following as per reccomendations from DIY via email.

Min dc from 21 to 22 ( to help with idle droop )

Fast idle "lower" 130 to 120

Slow idle ( upper) 169 changed to 140 RPM

Slow (warm) idle raised to 1000

VTPS theshold ADC from 150 to 10

Idle Activation 500 changed to 250

Dashpot settle time from 47 to 80

Dead band range 130 changed to 50

Fast recovery RPM 15 changed to 5

Slow recovery RPM 100 changed to 75


Thanks
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