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Altezza Rev Hang and idle swing


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hey im chasing an return to idle/ rev hang issue, ive been going around in circles this is my 4th attempt to make cl idle work, i can get a perfect stable idle with open loop no accuator and just using idle ignition control however i have to retard the timing all the way to -12 for it to idle and ther switchover point between wanting to use that ignition value and whats in my igniton main table makes the car a c**t to drive around car parks and in slow moving traffic and causes alot of pops and bangs not ideal. 

Today i adjusted the throttle stop to allow the throttle to be more closed from what it would be set at from a factory altezza throttle.

This let me get the idle down to 800 rpm without any ignition retard in fact is was around 24 degrees still ableto bring rpm down this tells me i can get the throttle closed enough to restrict airfloe and drop engine speed.

But my issue is when overcomming the idle lockouts the ignition values make the car rev hang and i dont know if i need to add more resolution in my ignition table or if i can make the throttle close quicker, i can see in my log that its not commanding alot of dc - to close the throttle.

Also smetims getting the tps/aps out of sync error so far this is the best ive manged to keep it from alarming out(aps self calibration still doesnt set the sub 100% value correctly it seems ). 

Can anyone please provide some insite as to what i need to get this working better

Log attactched here https://drive.google.com/file/d/1pndQRwTQztRH9RMmWtbQBua0xiyo9wnc/view?usp=sharing

rev hang and idle swing.pclx

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You google drive link is just another copy of the map, so I haven't seen a log.  But several set up issues in your map that should be fixed before you do another log:

1. You have zero integral on your E-throttle control, this means it will never actually reach target.  I would change your throttle PID back to the base map values below as a starting point which I have seen work well before:



2. Your idle ignition target is too high and the proportional and derivative are excessive. 24deg is close to MBT so you have little capability of increasing torque when needed quickly to prevent a stall.  Since E-throttle is relatively slow at increasing or decreasing torque, it is important to have good idle ign authority.  My suggested starting points:



3. Your idle speed control integral is too high, 0.02 to 0.05 is typical for e-throttle idle control.  Set this to 0.05 initially.  

4. Your fuel table could do with flattening out around the idle entry area:



Please do a fresh log after those changes are made.  You will likely need to adjust your idle base position table with some of these changes.  

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Sorry here is the log file originally,

Have made the suggested changes and here is a provided log from a start up car is already warm.

Car would idle better woulnt do as big of a surge to get the idle back on track after a undershoot but rev hang is very present, Cheers


Adam suggestions.pclx After Adam Suggestions.llgx

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Your E-throttle still has no integral.  As you can see this means the throttle will sometimes be a long way off target with no action to correct it.  



My suggested values:  2NVHehZ.png


Values in your latest map:  yYYltPk.png

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On 1/7/2024 at 6:32 PM, Twistcee said:

May need to up the target positions ?

Yes, as I mentioned yesterday.  

The log only covers ECT 80-84°C so cold start will likely need more work, but start with something like below should be closer than what you have now:


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Hey Adam so have the base positions a shot car started up after upping them a little more and the just adjusted them to what the throttle was actually positioned at as it was warming up, seems to start up hot and idle, just need to sort out idle undershoot after throttle blip now, if the values in the base position table seem hig it may be becasue i have adjusted the facotry stop on the throttle to allow it to close further as initally it seemed the carwould jsut not idle under 2000rpm without -15 degrees timing, how do i go about this undershoot problem cheers 

have provided log of warm up from cold: https://drive.google.com/file/d/1tYhjD4e-bv9IYLra8C0NJeyaQeSJ0Fvv/view?usp=sharing 

, did adjsut base positions as it warmed up and also have a log of a startup while hot it is only a short log but it does have the undershoot issue present. Also updated tune file provided.

short log restart while warm.llgx updated base positions tune.pclx

From the log it looks like when the undershoot happes the e throttle isnt actually being comanded to open it jsut stays at its base position, the timing is at its upper limit commanding 30 degrees advance but its not enough, or is it all to do with the timing of when it starts to command it, i suppose you could give it all the timing in the world but if it aint got enough air coming in then you cant increase engine output, this is wher im stuck, traditionally should the throttle be opening to aid in these events or do we go about it differently all togehter.

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The undershoot is a combination of idle control kicking in too early and no dashpot.  

Change the "RPM lockout above target" to 500RPM as a start, then you will need to experiment with dashpot offset, hold and decay.  Dashpot settings seem to vary a lot from car to car so I dont have a typical suggestion, start with about 0.4%offset, 0.5s hold, 0.2s decay.  

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Alright undershoot is fixed car catches idle fine, its not perfect but it doesnt seem itll ever stall, ill dial it in te more i drive it, my biggest gripe is the ammount of rev hang the car has its like half a second on light throttle blips, provided log of a drive and revving a the end of the log, any suggestions? 

Log/Tune here: 




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No tune attached.  

On 1/9/2024 at 11:41 PM, Adamw said:

Change the "RPM lockout above target" to 500RPM as a start,

What do you have the RPM lockout set at?  It looks more like it is set to 150-200 in your last log?  It should be close to 500ish.

I would also try the changes in orange below to the ign and vvt.



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Hey Adam have made those changes, and many more, here was the tune i forgot to upload, https://1drv.ms/u/s!Aos7W0SmQeO75gKbM6vpy4EsdPkO?e=ja2R0w

The IGN and VVT changes made a difference to the rpm drop rate but it is still seems excessive i also changed the e throttle target table to clloser to what come son base map and that made it slightly better aswell.

Ive been through so many forum posts and comparing tunes i cant seem to figure it out, as i mentioned right at the start the only way i could get the throttle response and decay to feel good was using excessive amounts of ignition retard as soon as im off throttle.

Comparing another altezza tune on a modeled fuel mode where he was having jerk issues at low speed ive noticed his fuel map to have decently lower ve numbers in the off throttle zone he does have it setup for facotry injectors, but given the same engine and my rev hang issues does that point out that A: my injctors are smaller than what i think they are (deadtimes could be off too, dug up from very old forum post theyre caldina gtt injectors) given im still pretty good on my target afrs given my ve numbers in the same areas im comparing or B my throttle is bypassing more air than i want itto be by either vacuum leak which im pretty certain if any it could be tiny ive boost leak tested and cant hear anything around intake manifold or throttle body.

could i have some sort of table that activates a ignition trim confined to activate just after those throttle blip scenarios, im struggling to think of a way to constrain that to only come on when i want it to without it activating while driving maybe by using

If aps < 2% While rpm < 3000 Then Igniton angle =-10 Until 500 rpm > Target

Here is the current tune in the car anyways, and a log of few revs. 

Tune : https://1drv.ms/u/s!Aos7W0SmQeO75hGGGhr7mqErHmoW?e=LjwkdU

Log : https://1drv.ms/u/s!Aos7W0SmQeO75hD3qnv8MVUuNX1c?e=8bnNVz 


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