1.6 Idle Valve Megasquirt
 

Hey all, anyone set their idle on a 1.6 with the stock idle valve? I'm using a MS2PNP, and I'm starting to get the impression that the stock idle valve isn't as configurable via megasquirt in the 1.6 as it is in the 1.8.

I've got it to idle at a decent position, but depending on the temperature it's either too high or too low, and changing the thresholds either makes it not idle cold or not idle hot. I've got them currently set the same, which doesn't seem right but has me driving mostly reliably.

I've been looking for a few weeks now, and maybe I'm just really having a mental lapse, but I can't find anything other than people with idle issues. I'm hoping the wealth of knowledge here can slap me on the wrist and get me pointed in the right direction. I know people have boosted 1.6s running MS2PNPs so surely there's something I'm missing.

I have been screwing with the idle on my 92 engine on ms2 since i've gotten the car running. I've ran countless IAC tests and have tried as much as someone teaching themselves over the passed year can.

In my experience it has never been perfect and i always end up settling for a 1100rpm idle as its better than 600 and constantly stalling.

The best setting i have found is using the "simple" PID slider and adjusting it to ~2500 or so. any time I've attempted to find P and I numbers that work well it usually is worse of a result than the slider scale.

Dont forget to set the base idle air screw on the throttle body BEFORE you start screwing around with the idle settings themselves otherwise the IAC is going to be fighting that which may make it lope.

Now I am on an MS3 so I do not know how much difference that is but I've been following the stickied tuning series.
I setup the valve as shown and it works however I have also found that tuning the startup enrichment and warm up enrichment play a BIG part.

Idle tuning should be done once warm with no accessories on and such.
Your enrichments and such will throw it off while trying to be helpful so get the warm bit steady then work back.

I have an odd thing when the car is warm and i start it again.
The valve opens and the various enrichments are competing to stabilise so i get this bouncing idle of about 500rpm or so but its trying to idle at like 2k.
I am also new to MS but i am having a whale of a time figuring it out as its so much easier than my previous software.

So how could you configure a cold start idle? Or do you just have one set idle that you're stuck with on a 1.6?

I'm amazed there's no aftermarket solution that the modding community has created. I'm about to start dismantling 1.8/1.6 Idle valves to figure this out.

I almost would've invested in a 1.8 and done the swap if I knew it was going to be this difficult. At least it is able to idle.

MS2 works just fine with the 1.6 ISC. No need to go down the path of finding out if the MS2 is compatible with the 1.6 ISC.

MS2 can idle a 1.6 @ 850 reliably.

Yes I could tell you how, no I probably won't. Just need to stop the propagation of misinformation.

My car idles fine. I just have no control over that idle other than it being virtually static. I can change where the static idle is, and raise or lower the idle depending on the AFR, but not with the idle valve. Every bit of information I've seen says that you should start at 0% in the idle valve output test mode and raise the PWM Idle Duty Percent until the RPM starts raising. Whether I have the valve mode inverted or not, raising the Duty Percent only lowers my idle. It just changes whether it starts higher or lower (normal starts me at an idle at 2000 RPM, inverted starts me at an idle around 1350.)

If I'm running the PWM Idle duty% test, I can vary the idle by damn near 2500 RPM. So, in theory I should be able to set a higher idle on cold start and have it gradually fall as the CLT rises.

I have researched this for months now, and I've tried just about every configuration of Idle valve type, algorithm, valve frequency, and valve mode. This really isn't a RTFM situation, because the manual doesn't apply on a 1.6 idle valve. I've found settings that are good enough to get me to idle at ~850. But none of those settings were configured using any method that anyone else has used that I've found.

There's no propagation of information, I'm asking a question, not stating facts. And "Yes I could tell you how, no I probably won't" makes you sound like a middle school bully. I didn't post nearly as much detail above as I did here, but I also very clearly didn't ask to be spoon fed base idle settings.

My idle changes depending on cold start, This should be easily configurable. The stock ECU was able to take inputs from the CLT sensor, the ISCV, the airflow meter, and change the ISCV position. The megasquirt has to be able to control the same dumb valve. Yet seemingly nobody online is talking about this.

Start at 35-40, go down. Stop when it stops changing, use that as the min. The 1.6 ISC has an inversion around 25% where a decrease in DC increases the RPM. IOW it is not monotonistic, and the PID requires monotonicity.

Min should end up around 25%

Edit: the 1.6 has a separate cold start valve connected to the intake manifold

I have my MS2 ready to install this weekend, I'll be keeping an eye on this thread...

If you have any questions hit me up, Also if you aren't already on the miata discord it's a great resource. Tons of knowledgeable people there. I've got the same username there so I'll be easy to find.

I have no doubt someone more proficient can get my car to idle correctly, however i truly believe my IACV is somehow screwed up and it gets "stuck" partially open and forces the idle very high(1600RPM randomly)

Also, after nearly a dozen times performing the idle test my values are quite close together at 12% and 31% respectively. I assume there would be a larger margin in a properly functioning one?

I've spent countless hours researching idle settings for 1.6's and pretty much all i've found are old tutorials and threads similar to this one with problems that most people aren't willing to help out with.

@Ted, that inversion you described makes a LOT of sense and it is the first time i've ever heard of that. I will retest yet again and see if i cant come up with better results. I really do appreciate the help! My sh!t idle has been driving me crazy for a year. I've also deleted my cold start valve as I wanted to simplify a lot of the extra coolant junk on my engine. besides having a lower idle when cold, i really haven't noticed any difference.