Reverant MS2-V3, need help with acceleration enrichment and idle A/C settings
 

Hey guys,

I've got a 2000SE (100% stock other than the GM IAT and MS2) running one of Reverants MS2v3's. I got everything wired up today, started up great and did some auto-tuning. Things seem pretty good, but I'm having a couple issues:

1. Tip-in acceleration: With quick throttle inputs, AFR goes very lean for 1/2 second and the car stumbles a bit. To fix this, do I need to turn on "Enhanced Accel Enrichment" under "Accel enrich settings"? Right now it has low RPM at 1200, high RPM at 6000. Should I lower the lower RPM threshold? Is there anything else I should look at/change?

2. Turning on the A/C at idle kicks the compresor on for about 1 second, but the rpms of the engine drop to almost 0. The MS2 seems to notice and turns the compressor off and recovers the idle back to 950 or so. After about 4 seconds the compressor kicks back on, and the cycle repeats.
Is this a timing/fuel issue? Is there a different setting I should look at?
I've included a datalog, initially the A/C switch is off, and turned on at approx 4 seconds.

Any help/suggestions would be appreciated!

What injectors do you have in there and which firmware version are you using?

I'm using the stock 260cc injectors. Firmware is: msextra_310_rev_MEGAECU.ini

Thanks!

I don't remember who you bought it from, buy you probably need to rescale your acceleration enrichment values, under Acceleration Wizard.

You will also need to upgrade the firmware, as the one you have is quite old and the A/C idle-up is not adjustable.

Thanks Rev. I bought it from GDSpeed, who bought it from rlogan (Who has/had a 99). I guess this thing really gets around. :rofl: I'll read up more on the accel enrichment values and work on tuning those up for my application.

For the firmware, can I use any ms2extra firmware? For example the ms2extra_3.2.1_release here: http://www.msextra.com/doc/ms2extra/....1_release.zip
I wasn't sure if the firmware was custom/specific to your builds, or if any ms2extra firmware will work in the future (thus being a good idea to upgrade when a new stable release is out, etc).

Thanks again for all your help!

you'll need his custom firmware

You can use whichever firmware you want, however expect certain features to disappear.

I spent some time reading/learning about the accel table, then tuning up my settings. They still need some work, but I couldn't stand sitting there revving in the 100 degree garage anymore. Overall things are much better than the previous values.
I'm posting the old/updated values here incase anyone else stumbles on this thread and wants to compare values.

I'm still not 100% satisfied with my accel enrich settings. I've got a Rev built MS2 on my MSM with stock injectors. My basemap settings were similar to yours, but I wasn't able to get clean throttle blips while downshifting. I increased the values to what you see attached, but I think I still need more fuel. It seems like my basemap settings for accel enrich were about the same as others who are running 500+cc injectors. Since its supposed to be raw PW for these settings and not % i'd expect mine to be much larger, but maybe I'm not understanding something clearly.

https://www.miataturbo.net/attachmen...ine=1343919531

I'm on stock injectors as well, here's my "final" settings that seem to work pretty well. Usually it spikes to ~11.5-12.5 for 1/3 second or so stabbing the throttle, I never really encounter hesitation under accel-enrich conditions anymore.

That said, I'm still having trouble with my idle during warmup with the A/C on.
From my datalogs, it looks like something's telling the idle valve to quit trying to keep the idle up, but I'm not sure what it might be. In this log, you can see the RPM drop after letting off the throttle. Idle Duty tries to increase for 1/3 second then "gives up" and drops to ~21 which causes the RPM to drop too low and die.

I'm theorizing it's related to my close delay time: it's set to 1 second so maybe opening the throttle then closing like that it doesn't activate closed loop logic and the idle dies. That or maybe my PID lockout rpmDOT, although I think that's only relevant for positive rpm/sec changes not negative.

I've been playing with the Idle Valve/PID settings the past 2-3 days, without much success. It's fairly humorous to me that what used to be the hardest part of aftermarket engine control (starting, dialing in the A:F ratios, etc) is extremely simple with the MS, but a stable idle is such a sore point. :)

I'd like to contribute since this is a problem i've been trying to solve for a while and finally found a way which is actually idiotically simple.

When idling the engine eats air at a low rate and pushing throttle 0%-->10% may lead into MAP going 30kpa --> 80kpa. On a higher rpm you need more change in TP to increase MAP. If the adjustmen of throttle takes, say, 0,5s going from TP 0% to 10% will result in 20%/s TPSdot value whereas going from TP 20% to 80% will result in 80%/s.

You could try cure this by adding some MAPdot AE, but it will not help since it's always late and causes problems with higher rpm (turbulence).

Here's what i did:

Config: 100% tps AE, duration 0,1s

First, tune your AE in normal driving conditions. Easiest way to do this is on 4th or 5th gear on a highway. Try it in different rpm readings (>1500rpm) untill you are relatively satisfied.

After that you go back to your VE table. Most likely you are idling around 30-35 kPa and 700 - 1000 rpm. Do not touch this area. Now do some quick throttle blips and watch that dot move directly up (and even to the left if it stumbles really badly) before the rpm starts to increase. What you want to do is to enrichen those cells right above your idle! In my case they were 500, 800 and 1000 rpm columns from 40 till 100 kPa. This is an area of the map you only use during startup, throttling from idle and when you are about to stall (ok being rich).

Start making throttle inputs first going to 50 kPa and add fuel untill you no longer go lean. Do not take your foot off immediately when the engine starts revving, but let it stable to see the real result. Otherwise you could mistake going rich during liftoff for going rich during acceration. Always wait untill the idle stabilizes before iterating. Then move to bigger blips untill you have covered your map all the way from ~40kPa to 100kPa. Do not touch the cells with greater than 1500 rpm since this is where you could be driving --> worse fuel economy.

Please someone correct me if i've overlooked something important. However, this is the way i managed to lose all hesitation when throttling from idle.