I've been getting my stock na6 going on ms2 and have been slowly working kinks out as i go. I've finally got the idle tuned to where it sits around 950 and i finally somewhat understand the PID closed loop tuning. However i'm getting a weird oscillation at idle that i can't figure out how to tune out. I've messed with all the PID settings and have tried VEAL the idle blocks however it keep's continuing. Here is a log of it happening i hope it helps. Thanks!!

edit: ive also added my current tune. please feel free to **** on it as i'm learning and could use the advice. I am not a complete noob when it comes to tuning an engine AFR wise however learning tunerstudio has been interesting.

 

Afr table needs work, ve table also, set same value for 4-6 idle cells. Don't autotune your idle.
You might want to consider lower timing values for idle.
Your CL Idle settings make no sense also, search for idle tuning, there are many great topics about it.

 

The AFR is dumb rich right now just to make sure it wasn't lean anywhere throughout the curve. I'm working on leaning it out.

As for the idle tuning, i most certainly don't know what i'm doing to put it simply. I'm going to redo the idle this morning using this guide Tuning Idle Valve - Ms2 - Guides: Forced induction - MX5Nutz Forum

Any other advice much appreciated!

 

It's a simple process actually, first you have to make sure you have correct VE and timing numbers dialed in.
Then using idle valve test mode, you're gonna determine your valve's operating range and Duty cycles for given rpms.
You'll have to dial these values in cl idle settings and initial values table, then tune closed loop parameters(try with slider 1/3 from left to right, or half and dial in P, I and D values.
Don't forget to tune thresholds, cl activation etc.

 

Redid my AFR table according to a few NA charts i've seen. I also redid my closed loop PID settings, please look those over. It's idle quite nice now around 900rpm and it has no noticeable oscillation. Im definitely still tweaking the initial throttle input where it had a tendency to be a bit lean(15.5-16 afr) however it's getting there.

Please let me know if anything seems super wonky, i followed most of the settings for the CL out of that guide however I did do the Idle valve test mode and used my own numbers there.


I have not touched any timing or spark as i really don't completely understand what, how and how far i should be taking things there. The car runs and drives well and i much prefer a conservative map than a risky more powerful one.

I should also add that i'm currently running NO TPS sensor. I plugged the stock unit as thats what I was told to do. I DO have a FM Vtps kit that i WILL be installing shortly. I already have the wires inverted and will get it calibrated and added in. I imagine this would help my intial throttle input from being lean due to lack of input and guessing by the MAP based charts now.

edit: i started off using the basemap from EFI analytics website.

 

Install that variable tps asap.
Timing is aggressive for 13.5 afr at 100KPa.
Chose the afrs you want to run for each load/rpm situation, tune for them(learn to use VE analyze live correctly, your ve table suggests you're not).
Ignition is heavily afr dependent, each afr gives different flame speed, so you need to tune accordingly.

 

VTPS is installed and functioning. I've read up a bit more and dialed in my idle a bit better and generally tried to clean up the AFR and ve table all around. Have been using VEAL with better results once i locked the idle cells. Have been tweaking the VE table a bit by hand as it was going a bit leaner on part throttle and decel than i'd prefer. Right now my decel AFR's are probably more rich than they need to be but i wanted to get rid of the popping on decel.

Is 13.5 at 100 KPA too aggressive as in too rich or too lean? This tune is to bide me over until I boost the car, I just simply want it to be safe and drive me around until i can pay a tuner to dial everything in with more expertise. 93 octane for fuel.

I do very much appreciate your help!

 

13.5 is on the lean side, try around 12.8 for good torque and safety.
Smooth your afr table around idle, that 13.5 part needs to be integrated.
You're gonna use overun fuel cut anyway, turn that on, dial proper values in your low kpa rows, set your overrun settings and decel percentage under accel enrichment.

 

I dialed the AFR's richer above 80KPA and it gets around 12.9-13:1 and seems to pull smoother for sure. I haven't been taking it to the high revs very much but when i did did not hear any detonation at 13.5 but I very much would keep it richer than leaner. I've educated myself a bit on timing at least on the miata and while the basemap spark advance table is pretty safe, it's only as safe as the AFR's you run.

I couldn't get overrun fuel cut running right so i've continued manipulating the bottom row cells to keep it around 15:1 for now. Still dialing it in however no more popping or anything too weird. I've stopped using autotone at this point and have been dialing in most cells by hand and using the smoothing tool to try and balance things out more nicely. More time consuming however the car is driving more smoothly.

It turns out i installed the VTPS but didn't properly switch the settings from MAP AE to the TPS AE. I've now switched it properly and the on/off throttle and low inputs are muuuuch nicer. I don't know if its totally normal but if i crack the throttle the slightest amount on decel(1-2%) the car runs rapidly lean to like 22:1 afr's. If i'm quick through that portion of the throttle when i get on it than it's not an issue. it really only happens when i'm stuck following traffic however it's just a habit from my BMW as the throttle is totally different than my miata in regards to input sensitivity.

Thanks again for the help! The car is driving nearly as good as the stock ECU at this point.

 

I would suggest zeroing the MAT table until your VE table is fully tuned. Also in general, that stock table (MAT) is too aggressive. Your cranking pulsewidth has a random huge dip at 110 degrees, this is definitely not correct. You will definitely have to mess with the cranking duty table as temperature changes to get starts without throttle modulation, as yours is fairly flat. Closed loop gain slider at 0? Closed loop idle initial values table will need tuning over time as that hasn't been changed. Ignition table looks fine, just keep on tuning and smoothing out that VE table. If you need any help with such things, I am running a ms3 on my basically stock na6.

 

MAT table? Havent touched that as far as i'm aware. I've been dialing in the VE table and the tune in general. I've gotten overrun fuel cut to work so i gave up on trying to dial in the bottom row of the VE table. For some reason sometimes it would go as lean as it should(18AFR) and sometimes it would go rich into 13. no idea why but over run fuel cut has eliminated that problem at least for now.

I havent touched the closed loop idle initial values table however the car starts(few cranks more than stock but not absurd) and idles without an issue. It doesn't rise to ~1400 or so and slowly drop like stock, but it goes up to 1200 or so and eventually when its warm it settles to 850 or so. It takes a while for it to come down from 1100 down to the 850 but by the time the coolant has warmed it usually drops. When the air temp changes the idle tends to raise or lower and the AFR changes slightly. i've been trying to find a happy medium to set it at so it doesnt go too lean or too rich in changing temps.

Definitely still learning however the car runs and drives nearly as good as the stock computer. A bit of jerking in 1st gear between 2-3k RPM that I can't really figure out the cause of but other than that its been good.

I definitely would appreciate the help, i'm going to go out and take a look at my MAT table and the closed loop idle initial value table and than save my tune and post it up so you can check out my current one. it's a good bit altered from the one i posted above.

 

I fixed that big dip in the cranking pulsewidth, no idea how that happened must have bumped it or something at some point. Here is the tune i'm currently running.

Edit: 1990 1.6, No AFM, GM iat near the throttle body, MS2, AEM x series UEGO, FM VTPS

Intentions: to turbo by spring. power goal-~180rwhp using a Kraken manifold, DP and full exhaust, CX intercooler, and turbo to be determined. Likely going to be the smaller Chinacharger from bell/Begi