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Idle control needs work.


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Idle control doesn't work very well with auto transmission, lol.

There is no way to quickly reduce duty cycle when shifting from drive to neutral, which is a pain.

Also power steer step is added every time the steering is moved. Even if idle is way over target, it just keeps adding until it hits max clamp. This is a bit embarrassing when parking as after a few small steering inputs to finish manoeuvring then shifting into neutral, it sounds like I've stabbed the throttle and takes ages to return to steady idle (even with gains maxed out and using -ve idle ignition correction numbers).

Perhaps adding a "return" option, where a negative dc% could be entered to instantly reduce duty cycle when shifting back to neutral?

And maybe an adjustable timer (minimum time between events) to lock out the power steer adder.



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Couple of things I've found today regarding this topic. (Turned power steer step off as it was shitting me. Barely notice the load anyway).

Note: Normal idle is around 24%DC, in gear is around 46%DC.       Max clamp is 55%.

With neutral/park step set to 22%:  Idling in neutral DC=24.6%.  Shifting into gear jumps to 46.6%.  (No other adders/steps active, base position 23%). To me that's getting up near 100% step?    Then shifting from drive to reverse or vise versa (so seeing neutral for maybe 300ms max), DC jumps to max clamp of 55%.

Shifting back from drive into neutral DC gradually reduces, so ignition control is needed to pull idle down until IAC catches up. This takes around 20 seconds with derivative and proportional gains max'd out.     But......if I tap the throttle after shifting into neutral, DC instantly drops back to 29% (which is where DC jumps to if I tap the throttle while idling in neutral).

I have logs and tune files to go with this if required.  

I would really like to get idle control sorted as this is a daily driven street car, which I also race hillclimb. It's the only real issue I have with the Link ECU. Conditional 4D lambda target modifier would be nice for lean cruise, but not essential. 

Cheers. Jay.

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On 6/5/2018 at 6:55 PM, JayGow said:

With neutral/park step set to 22%:  Idling in neutral DC=24.6%.  Shifting into gear jumps to 46.6%.  (No other adders/steps active, base position 23%). To me that's getting up near 100% step?

All idle up steps are adders.  So 22% + 24.6% = 46.6%.  It seems crazy that you need 22% neutral step, something like 4% is what I more commonly see.  If you are still using the Ford iac valve then they have big heavy spools in them so dont like any more than about 120Hz, this might be why you are seeing odd response.  It may be that doubling your DC barely effects airflow until you get to a certain point where all of a sudden the valve decides to open a big wack.  Can you try lowering your Aux 1 frequency to 120Hz to see if it improves behaviour?

You are right about the power steering and neutral steps if regularly activated will just keep adding on top of each other so we really do need some other settings that can take care of that but usually the CL looks after it well enough.

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Will try lowering the frequency. Didn't think of that, thanks.

My engine setup is a bit unique, lol. It has taken me a while to figure out what it likes as it is so far away from the factory configuration.

I think the large amount of neutral step required might be due to having to pull against supercharger vacuum. Also there is probably not enough vacuum to keep the supercharger bypass open (I've been meaning to check that).

I'm running a fairly long duration camshaft in it too.

Just a flag to drop DC back down the way tapping the throttle does would probably be enough. That works perfect. It's just not practical to have to tap the throttle every time I shift into neutral.

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Cheers for the input guys. Both good suggestions. Maybe this post should have gone in the G4+ section of the forum, lol. But I guess it's still relevant here too.

Here is the log with new idle settings. Can't upload map due to file size limit, but apart from idle settings it's the same as the above map.

 A rundown on what I tried:

Reduced solenoid frequency to 120Hz; seemed to make it more responsive, but still needs around 20% neutral step for a smooth transition into gear. The downside is now that the solenoid response is faster, the jump in steps when shifting from park, through reverse and neutral, into drive gives a pretty big shunt into gear if not done fast enough.

Smoothing the idle ignition; did give a smoother idle and force CL solenoid control to react faster, but needed a few degrees more step between cells to stop idle rolling. Tried to settle it with gains, but then it took too long to target idle. Best settings seemed to be D=3, P=5. Reduction values 10,11,13,15,18,'22'.

Without pulling a huge amount of timing, it does flair up a fair bit and take a while to come back down when shifting back to neutral. Definitely need a way to instantly reduce step. That seems to be my only real fix (besides tapping the throttle).

ECU Log 2018-06-6 7;52;16 pm.llg

Edited by JayGow
swapped D/P values
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I like this idea! I'll try that.

I have tried using map for y axis, but didn't seem to be of any benifit.

I still think a setting to subtract the neutral step would be the way to go. Trying to pull idle down with ignition while idle solenoid is bypassing a heap of air is a bandaid solution really. Hopefully the tech's at Link will consider this.

And prevent adding steps when conditions are repeated, eg power steer inputs and P-R-N-D. That would be great.



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As Adam mentioned 4% is a normal valve and the closed loop works well at such small levels. 

Another thing you could do is drop the timing down at idle in neutral and add more idle speed to keep the rpm up. That way there is less idle duty cycle between park/netural and when in gear.

With the 3d table add in more timing when in gear to keep the neutral to park idle speed duty cycle closer.

All else fails use a larger and quicker responsive iscv. 

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Happy to help.

Another suggestion is to use an auxiliary/fuel/ignition output to trigger a fix amount of air bleed using a solenoid. Then use a timer on this output. So when you shift though the gears the neutral step is not added as its no longer required or only now very small.

You could then use the 3d idle ignition for the power steering idle up. 

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