Mspnp idle issue.
 

1993 Miata, just installed MSPNP gen 2 with AFM delete a few days ago. I was able to get the idle tuned very smooth at approx 900rpm and 14.2:1 approx AFR (aem Wideband). The issue is that if I let the car idle for more than about 10 minutes the AFR slowly wander all the way down until it pegs at 10.0:1 and idle goes down to a very unsteady 750rpm. iat and coolant temp sensors readings look good. Driving the car hard for approx 15 minutes or so seems to fix the idle until you let it sit again. Other notes are that my Wideband seems to read substantially richer than usual when driving away from the rich/idle issue and slowly clears up as I drive. Not really sure where to go from here, any ideas would be appreciated.

-Matt

Can you post a MSQ and a log? Could be several things.

Attachment 164664

Attachment 164665




Ok, here they are. although it does richen up slightly in the datalog, unfortunately I couldn't get it to go all the way as rich as is was last night. it was doing it very consistently last night (I tried letting it cool of and restarting over 5 times last night and it kept slipping into really rich idle) so I'm not sure what that's about, but either way, id appreciate you checking out the .msq file to see if theres anything obvious that I missed/setup wrong. the only thing I can think of that I changed is somewhere in the middle of messing with the car last night I raised that idle some, but like I said I still had the rich idle thing happens even after that.


Thanks,
-Matt

Couple things.

You are running way too much ignition advance at idle. Open it up in TS, and start your car. Once warmed up between 27-29KPA ( where your car idles) try making the Idle KPA zones completely flat and try 12-16 degrees advance there.

Second, you have closed loop idle turned on, you don't want that since you are not tuned. Go to idle settings, select warmup PWM. Next go into PWM Idle duty table and tweak it if needed to hit your desired RPM ( you say 900, but higher it is easier it is to tune. I'd bump it to 1k and lower it later). It may have dropped once you lowered your timing.

Finally once it's stable as you can get it, open up your VE table. Raise and lower the 4 or so cells around it together while watching your KPA gauge. You want to tune Idle for the lowest KPA possible. Consider re-binning your break points if needed.

Wash, Rinse, Repeat until it runs great. Only then start worrying about closed loop. Its a steep learning process, but you'll get it. Post back after youve spent some time tweaking it.

Thanks for the reply. Please excuse my ignorance, but how do I turn off closed loop idle? On the idle control screen i see algorithm is set to "open-loop (warmup)" but I can't find another mention of open or closed loop.

wow! Thanks! Idle is WAY better now with the lower ignition timing. Still wondering if I'm missing something with the closed loop idle setting you mentioned though.

Thanks,
-Matt

Good to know. :) open loop warmup may be the same. You may be running different software than me. Using tunerstudio?

https://www.miataturbo.net/attachmen...ine=1457312764
Yep, tuner studio. This is what my idle control looks like.

You must be running newer code than me. I haven't updated in years. Start reading up on closed loop, and when you think you're really satisfied with idle, give it a shot, it'll be even better.