IAC Closed Loop Question

Tuning concepts, methods, tips etc.

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turbo conversion
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Re: IAC Closed Loop Question

Post by turbo conversion »

First of all using auto tune at idle is not recommended, do this manually.

Second turn off adaptive idle, it is not set correctly and keeping the timing at 15* when idling.

You need to get a stable idle with Open-loop (warmup) before trying closed loop.

Once this is set to Open-loop (warmup) you can then manually control the valve for the different loads and rpms.

Now you can set the IACV to what ever steps give you the desired rpm vs load and manually tune afr and timing.

I would set all cells from 30 to 45 kpa and 500 to 1500 rpm to 13.5 afr.

Start in neutral from your target rpm to say 1500 (changing IAC Steps to achieve 675 thru 1500 rpm) and manually tune these cells to target.

Once you achieve stability thru the whole rpm range you can then repeat these steps with the car in gear then tweak as needed.

David

EDIT: word
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:First of all using auto tune at idle is not recommended, do this manually.

Second turn off adaptive idle, it is not set correctly and keeping the timing at 15* when idling.

You need to get a stable idle with Open-loop (warmup) before trying closed loop.

Once this is set to Open-loop (warmup) you can then manually control the valve for the different loads and rpms.

Now you can set the IACV to what ever steps give you the desired rpm vs load and manually tune afr and timing.

I would set all cells from 30 to 45 kpa and 500 to 1500 rpm to 13.5 afr.

Start in neutral from your target rpm to say 1500 (changing IAC Steps to achieve 675 thru 1500 rpm) and manually tune these cells to target.

Once you achieve stability thru the whole rpm range you can then repeat these steps with the car in gear then tweak as needed.

David

EDIT: word

Thank you for the info!

I did get a nice smooth idle in open loop mode, but I read somewhere I would have to do closed loop mode to prevent the idle from dropping 200 rpms when going from park to drive.

I only recently put on adaptive idle as suggested by someone. Before my idle advance would not deviate from 16 degrees at idle. It will move if I give it some throttle. I did try to lower the advance manually while it was in gear to smooth out the 675 target but I did not get any results (whole truck shakes).

Will
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Re: IAC Closed Loop Question

Post by turbo conversion »

If not sure about anything in my post let me know, I'll try to break it down more.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:Once this is set to Open-loop (warmup) you can then manually control the valve for the different loads and rpms.

Now you can set the IACV to what ever steps give you the desired rpm vs load and manually tune afr and timing.
By this are you suggesting to go back to open loop, get my idle where I want it again, put it in gear and then manual move the valve at that load to keep the idle where I want it (at 675 rpm)? I have only been adjusted the IACv by changing the number of steps at the highest coolant temp (160). Can I have different positions for different loads?

turbo conversion wrote:I would set all cells from 30 to 45 kpa and 500 to 1500 rpm to 13.5 afr.
I have this done already. It keeps my idle pretty stable.
turbo conversion wrote:Start in neutral from your target rpm to say 1500 (changing IAC Steps to achieve 675 thru 1500 rpm) and manually tune these cells to target.
I am not sure what exactly you mean by this.

Will
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Re: IAC Closed Loop Question

Post by turbo conversion »

In the msq 1400 rpm is set to 15+ afr, if it is changed okay if not change this to 1500 rpm and 13.5 afr.

Get engine to operating temp. in neutral set IACV (in open loop) so you get 675 rpm then tune VE table (manually) to get 13.5 afr.

As you tune VE for 13.5 afr rpm may change a little so you may have to change IACV steps to maintain target as you tune afr.

Leave it in neutral and increase IACV steps so it moves to the next rpm cell then tune these cells to 13.5 afr.

Then repeat these steps all the way to 1500 rpm so from 675 to 1500 rpm your idle will be stable at 13.5 afr.

Now put the car in gear (load will change and rpm) so repeat the same steps through the same rpm ranges.

Once you have this dialed in you can repeat these steps in gear using lights or blower motor etc. to increase load and tune as needed.

After you achieve stable rpms and afr under all these different conditions you can then start tuning Closed Loop.

David

EDIT: word
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:In the msq 1400 rpm is set to 15+ afr, if it is changed okay if not change this to 1500 rpm and 13.5 afr.

Get engine to operating temp. in neutral set IACV (in open loop) so you get 675 rpm then tune VE table (manually) to get 13.5 afr.

As you tune VE for 13.5 afr rpm may change a little so you may have to change IACV steps to maintain target as you tune afr.

Leave it in neutral and increase IACV steps so it moves to the next rpm cell then tune these cells to 13.5 afr.

Then repeat these steps all the way to 1500 rpm so from 675 to 1500 rpm your idle will be stable at 13.5 afr.

Now put the car in gear (load will change and rpm) so repeat the same steps through the same rpm ranges.

Once you have this dialed in you can repeat these steps in gear using lights or blower motor etc. to increase load and tune as needed.

After you achieve stable rpms and afr under all these different conditions you can then start tuning Closed Loop.

David

EDIT: word
When I try to do this my idle 675 sits between two cells (501 and 801 - took a pic of this but it is too big to upload on here). At this point i'm not sure which rpm cell to adjust the 501 or 801 to get the desired effect. If it is a little lean I try to increase the VE cell but the 501 or the 801. The hardest part about this is that the AFR is not constant on its target of 13.5. I can get it in a range where it will go 13.5->13.6->13.7->13.5->13.4->13.3, and up and down like that. I can't get it to stick on 13.5 for any appreciable amount of time.

Datalog:
2017-03-19_14.33.05_Beginning.msl
MSQ:
Sammy 2_2017-03-19_14.53.47.msq
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Re: IAC Closed Loop Question

Post by turbo conversion »

I made a few mods in the idle area and rpm range of the VE table, this is an example of what it may resemble once tuned.

You can load this msq and try tuning the idle area strating with these settings with a warmed up engine.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:I made a few mods in the idle area and rpm range of the VE table, this is an example of what it may resemble once tuned.

You can load this msq and try tuning the idle area strating with these settings with a warmed up engine.

David
Ok, so I warmed it up with my tune and then switched over to the mods you made (thank you very much for that). It already idled better, but I was getting different AFRs on different starts. I did a couple datalogs:

First one:
2017-03-26_13.47.15_Davids_Mods.msl
Second one:
2017-03-26_13.53.50_David_Mod2.msl
I started trying to adjust the tune and apparently could not do any better then what was on here which lead me to a couple of questions.

1) How steady can I expect my AFR to be at idle? Will it lock onto 13.5 and hold it there?
2) How important is fuel pressure fluctuation? I have an inline fuel pump capable of 9-17 psi with an adjustable fuel pressure regulator in the throttle body. I have an electric fuel pressure gauge mounted so I can have constant monitoring of the fuel pressure. I noticed when it starts and the idle is high I have 12 psi (which is where I thought it should be), however, when the idle starts getting into the 675rpm range I noticed that the gauge will jump back and forth between 11 and 12 psi.

Will
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Re: IAC Closed Loop Question

Post by turbo conversion »

What ever the factory fuel pressure (for the injectors you are using) is supposed to be is what I would set it to.

Fuel pressure at idle should hold steady, if it is fluctuating then afr will go slightly lean or rich.

With throttle body injection you are not going to be able to get a perfect 13.5 afr at idle, it will drift around a little (+ or - .2 afr or so).

If you are not getting any oscillation at idle then I would call it a day and move on.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

Got my open loop idle (While in neutral) straightened out but just cant seem to get my idle up high enough when putting in into gear.

Trying out closed loop mode again. This is the MSQ that I put together using the manuals:
2017-04-18_23.45.42_Closed Loop_again.msq
Will
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Re: IAC Closed Loop Question

Post by billr »

Post the MSL, too.
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Re: IAC Closed Loop Question

Post by ironwill11 »

billr wrote:Post the MSL, too.
Here is the datalog:
2017-04-19_19.03.08_CL_Mystery.msl
Will
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Re: IAC Closed Loop Question

Post by billr »

Try raising the last (highest) temp in your "closed-loop idle target" up higher. It is presently about 143F, under where you are idling, and I'm not sure if MS sets the target flat at that last value from there on, or extrapolates the target to a lower rpm based on the preceding shape of the curve.
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Re: IAC Closed Loop Question

Post by SwedCharger-67 »

Your closed loop doesn't seem to be working, your stepper motor never moves after stopping at 20 steps.
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Re: IAC Closed Loop Question

Post by turbo conversion »

Give this a try and see if the stepper motor will move on it's own, let me know.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
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Re: IAC Closed Loop Question

Post by ironwill11 »

billr wrote:Try raising the last (highest) temp in your "closed-loop idle target" up higher. It is presently about 143F, under where you are idling, and I'm not sure if MS sets the target flat at that last value from there on, or extrapolates the target to a lower rpm based on the preceding shape of the curve.
That is a good point, I didn't think of that. Just assumed that it kept it at a flat rate.

Will
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Re: IAC Closed Loop Question

Post by ironwill11 »

SwedCharger-67 wrote:Your closed loop doesn't seem to be working, your stepper motor never moves after stopping at 20 steps.
I noticed this. I wasn't sure if it was supposed when it should enter into the closed loop mode or not. I know the manual talks about tuning for entering closed loop and then tuning once your inside closed loop but not really a good explanation of when closed loop should be happening.

Will
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:Give this a try and see if the stepper motor will move on it's own, let me know.

David

Give what a try? Raising the highest temp?

Will
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Re: IAC Closed Loop Question

Post by turbo conversion »

Here you go, sorry.

David
1976 Datsun 280Z L28ET Garrett GT35R T3-T04E stage3 50 trim 63 A/R housing custom grind cam 2000-6000 rpm 440cc injectors intercooled 18 lbs. boost
3" exhaust turbo back LC-1 o2 sensor Hallman manual boost controller EDIS 6 ignition batch fire 60mm throttle body 5 spd T5 borg warner 3.54 lsd
ironwill11
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Re: IAC Closed Loop Question

Post by ironwill11 »

turbo conversion wrote:Here you go, sorry.

David
I am not sure what you did or what we what the result would be from what you did. However, I did not seem to note anything different. When I ran this datalog.
2017-04-22_16.29.15_Davids_Datalog.msl
However, when I did another datalog after moving the temp up for the the target idle I noticed that I put it in gear at one point, the rpms dropped, then they very slowly started coming back up.
2017-04-22_16.37.21_Billr.msl
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