I've spent spread out portions of the last 2 years trying to tune my MS3x between classes. Now that both my wife and my daily drivers are going to be in the shop coming up i've gotten more serious about getting the car reliable.
I finally ironed out some of the major problems I was having and isolated what I guess is a major problem now. I got the idle and AC idle up spot on last week, drove the car to work for a few days AC blasting with the only problem being the MTX-L overheated, no problem, I have copper sheet i'm about to make a heat sink with, no problems at this point...then the weather warmed up...
I work night shift so driving the car in the other day was flawless, driving home was equally flawless. Idle is spot on, no longer trying to die at lights or traffic. I get home, take a nap for a few hours, start the car to run to school, then my old problems came back to haunt me.
1. Cold starting the car after sitting in the 75* sun, it absolutely refused to idle. Would freely rev, but would instantly die with no throttle.
2. Driving down the block with the AC on, I had what would seem like a fuel cut anytime I gave it more than 30-40% throttle. If I remember correctly it goes way lean. Now that I type this I could be off and it could be way rich, but it's not variable, it's like a button is pressed which cuts the ignition until I let off throttle. I can hear the butterfly open and engine tone change, but zero power. This is not consistent. Will do this only half the time, sometimes it will accelerate 100% fine.
Now if I so much as hit the AC button and turn it off during one of these episodes the car will instantly rev up with 100% power.
I was not able to find anything like this by searching, maybe yall can give me an idea where to start. I have a log of me trying to start with no idle. Not sure how useful it is since the car instantly dies. I have logs somewhere of the AC ignition cut somewhere but I have to go to class this morning, i'll sift through and post them today around noon.
Anyone have ideas where to start here? The car is near daily drive reliable if I can just get it running when the sun is up.
Thanks in advance.
Car is a 94 N/A, light flywheel, exhintake and exhaust boltons, stock other than that. Edit: Also I have no idea what i'm doing on this mess, lol.
Last edited by Jiggerachi; 02-11-2015 at 08:48 AM.
Attached the msq and the no idle log. My apologies, my kids woke up so I've got to get on the road. I haven't looked at the log yet but when I get back i'll go through it and get the log for for the AC thing.
have you tuned your MAT corrections table?
have you tune your idle VE map to work well when the a/c is on running at like 40kPa vs 28-30kPa?
I have not tuned the MAT corrections table, until now I didn't know I needed to as I was able to get the car running fine until the weather warmed up and changed everything.
The idle VE map has been tuned to work with the AC and idles solid AC on or off...when the car has been parked in the shade.
I'm not sure you're understanding the problem I've ran into. I've got the car idling perfect with or without the AC on. On a cold start if the sun is out and the hood is warm the car does not want to idle at all with or without the AC on. The ambient air temp was not any higher, the only difference is at cold start it was parked in the sun vs previously being parked in an underground garage. The way I understand, I don't think the idle table is the issue here, some other sensor is. However i'm no expert so I could be dead wrong.
Originally Posted by Braineack
the only thing a/c does is add load. if everything else is getting out of whack it's because you told the MS to let **** get out of whack.
I understand this, I thought I had corrected for the extra load in the idle up and idle VE, since the car runs perfect if it's been parked in a garage. The sun warmed cold start idle problem has thrown me for a loop. Again I don't think the engine is not compensating for the extra load, the higher cold start temp seems to be screwing with the IAT or something else.
Oh BTW this is your old MS3x out of your car. I believe I'm working on the settings you sent with it as a base line. IIRC you said most settings should be good for an NA car and you rewired it for a '94 1.8. Some settings could be left over throwing everything out of whack with cold start temp increase.
Originally Posted by Braineack
reading your post is just sounds like you haven't tuned at all, or dunno how/what to tune.
You would be 100% correct here, I don't know what i'm doing, but i've been reading and learning. Problem is I bought the MS3x at a time when I had time to learn it. A few months after I transferred to engineering dept at a university and changed jobs to a night/weekend shift so my free time went bye bye and the car basically sat in a garage for a couple years. Now i'm trying to do what I can with the time I have. Not a perfect scenario I know, but it's what I got. Believe me i've been reading and searching, i'm only posting here since I got everything running what I thought was fine but seem to have some critical issue with a warm sensor or something and i'm at my knowledge limit.
Thanks for the MAT corrections tip, i'm reading up on that now.
I've attached the tables that have been mentioned. I attached the boost control settings as boost control is set to ON, being an NA car this is probably unnecessary and should be set to OFF, but could this be causing any of the mentioned issues?
Originally Posted by Braineack
the MS3x or the MS3-pro?
if on the on Ms3x, I'd update to the newst ms3 firmware. They made improvements to the mat corrections.
I will update, however this problem has plagued me through a previous firmware update, and that update opened up a can of worms that took a couple days to sort out. Since the car is running decent in spite of the hot weather issues, i'd like to get to the bottom of them before introducing more variables.
I took the car out just now for some logged runs, wouldn't you know it car ran completely fine. Conditions are same as yesterday when it broke down on me. No idea why this is so sporadic.
Only caveat is I am able trigger the AC ignition cut thing every time entering the freeway. It will happen 100% of the time in 3rd gear, full throttle, around 5kRPM with the AC on. Basically the engine will not accelerate past 5k no matter what. Keep the gas pedal down, car will decelerate until I back off throttle. No AC, that range is fine.
Some of my ignorant thoughts on the matter: it has to be related to engine load since it gets worse with each successive gear, e.g. 2nd gear will cut ignition close to redline, 3rd gear will cut ignition around 5k, 4th, maybe around 3k, etc. This seems to be common regardless to temperature, but I admit I haven't tested it fully in this manner in cold weather.
Has to be related to temperature since on warm to hot days, after sitting in the sun, this will happen seemingly random times like around 3 or 4k in 2nd, 3rd, not even past 1 or 2k, when it's at it's worst.
Has to be ignition retard or cut because when it just happened on the freeway run the AFR stayed pegged around 15.2, didn't change. So to correct the earlier assumption I don't think it's a fuel cut and I should have said ignition cut in the title.
I've attached the log of the run I just did. The problem happens during the long acceleration near the middle of the log. You can see the idle is fine when I parked at the end.
Thanks again for the help, I admit I got in way over my head with tuning, I have a TON to learn still but not a lot of time.
I've got a midterm to study for so I'll check back in later.
Edit: I went through the log and I forgot I didn't start a new log before the freeway run, I can't find how to trim the log and i'm out of time. It happens around 75% of the way through. Here is a screenshot of the exact event, notice how RPM is pegged around 5200.
Last edited by Jiggerachi; 02-11-2015 at 02:37 PM.
This is the problem. The RPMs stop rising because the throttle is open but the engine is effectively dead. Like the the injectors or spark plugs stop firing until I let off the gas.
Not ignition huh...can rule that out. I understand now. I guess it's suddenly leaning out under heavy load? It feels just like a computer induced fuel cut, not bouncing like a rev limiter though. You know what, it feels exactly like my weedeater when I give it too much gas with an open choke when it's cold.
All of my maps. These are the base NA maps that came with the MS3, i've played with the idle area, bumped the timing a bit and autotuned, but I haven't tried to adjust much in upper RPM.
Last edited by Jiggerachi; 02-11-2015 at 03:10 PM.
Anyone have feedback about these tables? I always thought the AFM table's upper right cells could use to be a lot higher but want to fix whatever the hell is happening first to keep from introducing more variables. I've just about got it isolated now.
But would it be worth it to try to bump the AFM table? Anyone have a good NA table they can share? I never could find anything to compare to and while driving I thought performance in that range was ok, guess i'm way wrong. How badly can that AFM affect things in that area of the map? Could that lean condition be a portion or all of my problem?
Still doesn't address the weird idle thing though.
Your target AFRs are too high in your acceleration sections (higher load areas) of the map. Try adjusting any of your 70kpa and higher cells that are higher than 13.0 down to 13.0 and then autotune on "very easy" until it finishes making changes. If it is indeed a lean miss then this should help. If the autotune adds a bunch to the values in the VE table but the AFRs don't respond by richening to match the targets, then the fuel pump isn't keeping up and will need to be replaced.
You may choose to fine tune your AFR targets a bit after this experiment but please remember that anything above 70-ish kpa is not an area you should set up for "lean cruise" AFR values, but rather for values matching the need for acceleration under a load. What you have now is a de facto fuel cut, even though that was not your intention.
Ahh! I see that now. That's a pretty good sign he's got a dying fuel pump (or clogged filter).
His targets are still too lean in load. Jigger, the car would accelerate much better while naturally aspirated with a little more richness up there. Give it a shot after you replace your pump.
Is hot weather known to aggravate a dying fuel pump?
So the theory is fuel pump is dying(or filter clogged) and putting out just enough pressure to not cause issues most of the time, the AC adds just enough load to overcome the given fuel pressure at WOT and high RPM. Would make sense why it cuts power at lower range in each successive gear.
Sun warms up the pump, starts going haywire, if it's in the shade it seems to work normal albeit at lower pressure than required at high load. The temp range difference would point to the pump rather than clogged filter in my mind.
I'll look into getting a new fuel pump. Would be hilarious if that's the case since the fuel pumps in both my wife's Nissan and my MINI have died this month, it'll complete the trifecta.
I'll work on the AFR table in the mean time, but I guess that would just make the problem worse.
I'm pretty choosy about gas stations usually. I've only had the MINI a year, and i'm super picky with it since it's the turbo so I avoid all shitty stations, usually go to the QT since it's the nicest in the area. The Nissan is whatever and was a well known sensor problem and the MINI HPFP problem is so prevalent BMW issued a special 10y warranty on just that part, some guys have gone through 3 of them in a year.
The Miata has had weird issues stemming back before I lived in this area that now seem like the pump could have been bad all along. It's averaged less than 300 miles in the last 3 years so that can't be good for gas to sit that long either.
Still though I wouldn't doubt it, stations around here are really shitty. MINIs have a lot of issues attributed to shitty gas from what i've read.
Last edited by Jiggerachi; 02-12-2015 at 05:48 PM.