My A/C weirdness continues.

I have pretty much dialed in the idle with the A/C off, it's not the smoothest but I'm getting there (I think I might have a vac leak or a shitty injector, I have 4 equally flowing cleaned up NB injectors that will be going in soon).

Anyway, this started in another thread but I was having other weird issues that have been somewhat solved. (With A/C on, if I pressed the clutch the RPMs would drop bad, now it's good).

The problem I have now, is that whenever I turn OFF the A/C, or the TXV cycles the compressor, the RPMs drop A LOT, under 500, sometimes it dies.

I have attached a log, but for some reason, right before ADC6(or 7) (which I think it's the A/C in/out) changes states, the idle RPM target goes down to 900, while the compressor is still ON, which causes it to pretty much drop the ball.

Here is a graph:

The Yellow line is the IDLE target, it goes from 1100 to 900 out of nowhere.

The green is the idle valve dropping out, then coming back up when RPMs are at 750, but it's too late and the RPMs continue to drop to 550. Them it comes back up again overshooting, a mess.
Any insight? I thought that perhaps my idle valve was sticking or something, but it seems like the ECU is actually making it drop down.
The ADC6 or 7 drop AFTER the idle PWM has been modified.
if I set the min PWM% higher, it might help, but then I get an idle speed that is too high when idling w/o AC.

I'm getting too confused to continue playing with this, please help?

 

is the value it dropped to the same value that it started at before the a/c turned on?

 

Idle% goes back to closed valve%. I've kicked it up a bit to 36.1% since I posted, so it goes:

AC off: Idle% 36.1, RPM target 900
AC on: Idle% stabilizes at 49%, RPM target 1100
Ac off: idle% immediately back to 36.1, RPM target 900, but RPMs die.

Status of AC goes down to 0 AFTER the idle drops the RPM target, which is weird to me. Unless it's logging wrong

Edit: I do NOT have idle closed loop set to use last value, if that's where you were going to. I have it set to use initial values. After AC goes off the pwn goes to closed value I believe.

My closed value is actually way lower than 33, but I found that it causes weirdness if I set it too low

 

can you post the tune and log?

 

This is the last log I have.

The tune should be the same as the posted in the first post with the idle closed valve at 36 instead of 33. I might have also changed dashpot adder timing but I don't think it helped.

Also I've noticed that for idle changes one MUST power cycle the ECU, it's not required by tunerstudio, but it seems like the reference numbers are off. If I change my IDLE targets, the ignition advance does not reset until I turn off the ECU. So if I drop the target, the advance will think that 0 is still in the old value, or something like that. Once I restart everything it's all synced up and everything runs better.
I might be wrong though, but it's worth looking into if anyone else is testing stuff.

There are two logs, they were made during WUE because I had limited time at lunch. I'd use the first one (AC on off WUE) since it's shorter and cleaner, it should have two cycles.
The other one is longer and more random just in case the other one is too short.

Thanks by the way! I appreciate your time spent on this

 

I find that it leans way the **** out when that stuff happens.
I wonder if I should mix up a bit of mapdot accel enrichment with my TPS enrichments... Altough it shouldn't matter right?

This also happens outside of CL idle, I tried warmup only (which actually idles ******* awesome) and the dip still happens.
I wonder if it's something outside the ECU, like something in the AC system, or electrical.

 

In for Education.

EDIT:

Nicolas,

You do need to set MAT Air Density Table (under Basic Load Settings) to 100% across the full temperature range. This is one of the last things to tune, and when you do tune it, it will be more like 104% at 0 (cause really, will your car EVER see -40) to about 97% at the top: WAY less than the default, mess you up setting.

If I had to hazard a guess, it would be that your delay is too long. But, honestly, I'm not sure that is the cause.

A possibility: You're minimum idle valve is 36.1, but your Initial Values Table has targets as low as 32.9. This does not make any sense. If you have tested the idle valve minimum, and the 36.1 is correct, then none of your Initial Values should be even that low. If you have not legitimately set your AIC Duty Cycle Min and Max, you need to do that.

 

The cause for the discrepancy with the initial values is that previously I had the IAC set to 32.9 as the minimum, so both were the same. But you're right, it's something that needs to be corrected.
I think I need to make a plan and stick to it. Those initial values were acquired by moving the IACV in test mode to match the RPMs in each cell, but later I played with the fueling at idle, and those things kinda change a bit. I'll leave everything as is and I'll try to get those values set again.

I had my closed valve value set at the same number as the value that allowed me to have the idle where I wanted it.

So if 33 gets me at 850RPM, then I'd set it at 33 so whatever happens I wouldn't be under that value of 850rpm, trying to correct this A/C issue.
What I don't know is if in open loop the values picked up are from the table or if those values are only used during CL idle and in open loop the valve just goes to closed.

If the open loop looks at the table and I have it lower than the closed value I'd see a problem, but I just want to clarify that before this last change the values were matching.
I'll change them anyway and upload logs again, HOPEFULLY it will fix it, because it's getting hot as **** and my car dies at almost every light if I wait long enough for the compressor to cycle.


On another note, why would I have to play with the MAT table? Wouldn't put everything at 100% mean that the air density is constant across every temp? Which isn't? Wouldn't that remove the IAT measurement from the fuel calc formula? Just asking, not really sure how that works.


Thanks!

 

1) Wrong approach to setting minimum. See the MSExtra Set-up Manual. The Max number is negotiable, the Min number should be set to what gives no more change to idle speed.

2) Trust us on the MAT correction. The theory of Speed-Density just does not play out in reality.

3) Initial values cannot be set for the range of MAT in a single sitting, because you don't see a range of MAT. It takes time. BUT, you can get the normal ones set correctly (Full CLT temp -> Target RPM + MAT and read your DC. Plug that into the table where it belongs. That is a start.

4) Again, I don't know the full ramifications of a target DC value being below the MIN value, as I don't know the intricacies of the PID loop.

5) Have you tried adjusting the delay from 700mS?

 

DUUUUDE. I changed that MAT thing to 100%... holy **** so many issues resolved. My idle off A/C is way better. I can now idle at 14.7 SMOOTH. Before it would do a miss even with new spark plugs. I even purchased new injectors to work around that. ****. Also hot starts I don't get my AFR going to 17:1.

The A/C thing is not 100% fixed but I gotta say it's WAY better. It only dies when I have the fan set to 4, I think it draws too much power, but at 1-3 it works almost normally.
I get a peak of RPM now after the turn off but I'm almost positive that's my CL idle settings being messed up, I gotta play with that.

I have hunting while the A/C is on too, but I can fix that with idle tuning.

I don't know what fixed it the most and I'm curious so I'll probably move the A/C delay back to 700 to see if that breaks it, so future miatas know.

 

By the way. My idle sits at 33-35kpa, I've read other Miatas idle at 22kpa, wtf?
Do 1.8s idle at higher vacuum? If this value is too high I'm thinking two things. Either it's the case because of my idle screw being far too open? But it's required for it to idle at 850rpm :?

The other thing I can think of is my injector o'rings, but again, wouldn't I be getting idle too high?

 

Your idle kPa is fine. I'm not sure where you heard 22. That is over-run territory.

 

Yep, that's what I get in decel. I guess I read that people were getting between 28 and 30, not 22 lol.
Is there much importance about tuning for highest vacuum at idle? I guess that would mean getting the same RPMs with less air and therefore less fuel (if you manage to keep AFR constant). I just tuned it to 850-900ish and I'm trying to lean out as much as I can in the idle to save fuel.

At some point I got 31mpg combined and now I'm back at 25 which is what I get stock, but I'm also driving like a retard so that might be it. I would love to get some better mpgs... anyway, I'm drifting away. I charged my laptop, I'm ready to do some more parking lot idle testing now. I'll report later.

 

Well it looks like the delay has something to do with it.

Initially I had it at 700ms. Droop.
Then Moved it to 300ms, most of the time no droop, but turning off the a/c would make it kick higher than idle target for a moment to around 1050rpm.
Moved it to 400ms now and there is a slight droop, so I guess it needs to go at 350ms.

I've also played around with the limits of the CL idle and the overrun. For example leaving the idle valve closed above X rpm, I had it in the low 1X00, I moved it up to 2000 to discard that being in the way, since sometimes the RPMs would climb up while trying to figure out the A/C and then it would close the valve, doing weird ****.

It seems like the dashpot adder also activates when coming out of A/C, because I've been playing with that value to adjust the kick in RPMs after the a/c turns off. I actually turned it down once I got the idle to not kill the engine because it would drop to 950 and then kick up to 1100 with the a/c off.

I've also moved the kpa limits around for overrun and CL idle to give it some more room.
Anyway, there is more to play with, it gets messy with all the RPM and MAP limits in many different places. I think TS should re-organize some settings and group them differently, but it's just my opinion.

What I've noticed is that with the A/C on my overrun limit moves up to 2000rpm, but this might be because having the idle valve open further I might not be hitting low MAP so the overrun gets disabled.
I had to correct a few things because the overrun would fight the idle and I would get on-off injection at 2000rpm.

I know this all sounds like a mess so I'll attach my last tune.

The last thing I need to work on is that it doesn't jump inmediately to target RPM. I turn the A/C on and it sloooowly climbs from 950rpm to 1100rpm (target for now, it runs rough at 1000 for some reason). And I've tuned the I in PID of the CLidle higher than others, I have it around 40-60% and it still takes some time to hit target.

 

You're on your way. Keep working with it and your understanding will get better and better.

Too many things in too many places may be what MS3 1.5 FW "engine states" is trying to overcome. Not sure.

I don't use close delay. I don't see the value and it complicates things, as you have noted. Set it to "0".

 

I don't even have the option, but it looks like there IS a delay from AC off to IAC back to normal, but it works backwards? IDK. Seems better now, I brought lunch to work so I have more time to play with it.

By the way, I noticed I never stated what the **** this is running on.
It's a 1.6, 1989, all stock, I still have the MAF and all that ****.
And the MS is a DIYMS2

 

Ooook.

I've done some testing. The issue has changed a bit. Before I'd turn off the AC with the switch and it would do this drop. Now it seems to be a CL idle issue.

So whenever I change the fan speed from 2 to 3, 3 to 4, or 4 to 3, I get the drops. I THOUGHT that perhaps the AC switch was cutting off, but I'm not sure anymore, it seems like something weird is happening, the AC status stays on for a biiit longer, long enough for the idle to die. Now when I switch the AC off manually everything is graceful. It's either when the TXV cycles or when I change speeds, even when I change speeds DOWN. Could it be the switch cutting off between speeds?. I think the problem might be on the RPMdot settings of CLidle but I don't really understand them all.

So here is what happens:

WHITE: A/C switch
YELLOW: CLIdle target, UP is AC, down is NO AC targets
Green is PWM%
Red is RPM

You'll see that BEFORE A/C switch goes down, the CLIdle target has already dropped to 850rpm, while the compressor is engaged. This kills the rpms, so the idle compensates somehow.

White goes DOWN once the RPMs go UNDER the A/C RPM limit, until then it stays put.

Why the ****? I don't know.