I am trying to establish open loop idle with the $42 bin. Vehicle has a 383 with patriot heads, a Comp 260XFI cam and 82 lb injectors. I am frustrated by a surge at idle when in neutral and on decel and light throttle when in drive. I have tried changing open loop idle AFR enable and disable thresholds around and it still wants to enter closed loop idle. Can anyone give me some pointers on this?

I used to run a 7747. Hard to recall. Is there a bit to check in constants for OL idle?

Is there a MPH threshold to enable CL that you can increase?

Also consider changing the SA "corrections" to zero. I forget what they are called. SA might me changing. I also change adjacent SA tables (rpm/map)to same value so if it wandered to adjacent no change in SA.

I would change one thing at a time(thanks Grumpy). Also maybe consider lowering the proportional gains maybe 10% at a time and see if that has any effect. I had exact same issue as you and it is improved significantly.

Check you pulse width at idle. I suspect it is moving around. Same on SA.

Oh yea almost forgot. Consider idle "synch'. Consider disable of asynch fueling altogether. I think that may hinder max PE fueling so watch DC there.

I thought I had a post on this that described the parameters. But alas, I can not find it. Did find this:

http://www.thirdgen.org/techboard/di...an-i-idle.html (How can I idle in open loop?)

Check those parameters in either ANTZ or ANTY. They a BBC BINS that I am sure ran open loop at idle.

Actually, looking at the linked post, those are the values to use for open loop idle. Ha, I didn't even read my own post correctly, lol.

RBob.

First off thanks for your replies. I'm not sure why I couldn't find RBob's post in a search. I'm using the Tunercat definition file to edit this so some of the parameters are labled differently. I am assuming at this point that:

'OPN LP IDLE THRESH' = 'Speed to Enable Open Loop Idle',
'OPN LP IDLE THRESH TPS' = '%TPS to Enable open loop Idle',
'Open loop RPM thresh idle off' = 'Open Loop Idle AFR Disable RPM Threshold'
'Open loop RPM thresh idle on' = 'Open Loop Idle AFR Enable RPM Threshold'

Is this correct?

Looking at the settings in the example given in the link it appears that open loop idle will occur between 950 and 1400 RPM? Since the parameters are labled differently in Tunercat it makes this a little confusing...

Tunercat generally adds whatever might not be in their program if you ask. They are good at that.
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I will guess it enters OL at <1400 rpm and leaves OL I at >950 rpm.

transition?

Enters < 2 mph and enters < 2% tps.

That was what I was thinking. I am thinking that there is no reason for it to only activate idle between 950 and 1400. What happens when idle drops below 950? Seems that it might cause it to surge again. I guess I'll try it and find out. I'll let you know how it works. FWIW I don't see any switch in constants for OL idle.

switch may be specific for $61 or EBL.

I have now managed to get it to open loop idle but I had to lower the Enable RPM Threshold to 500. Strangely, it doesn't always go to open loop when I slow down and I have been unable to get it to open loop idle while coasting, only at a complete stop.

Try setting up the open loop decel option to be active. Need to set b3 ($08) at address $06. Note that this is a single bit flag, so whatever is at address $06 gets changed to have that bit on along with whatever other bits were also on.

Then the OpLp decel parameters follow the OpLp idle params:

RBob.

{edit: here are the parameters from ANTZ, which runs open loop decel. Address $06 has bit 3 set}