Hey gents. I have searched and found a few related threads but nothing conclusive. I have been running MS for about 3 months on my NA 94. Turbo in the spring. Anyway I am having an annoying problem and I cant seam to come up with the solution. I have for the most part used MLV to tune most of my map. The 4 cells around Idle are done by hand. My cold starting is not great but works, and I'm refining it. The problem I have is that once running after 2-3 min, right at the point it drops out of warm up regulation and no longer registers in the warm up wizard window, but before it has really hit full temp. I get very lean numbers at cruise. Like 18's With surging (natch). anything past 1/2 throttle is ok, it jumps right back down into 13/14 but at a cruise silly lean. this lasts for around 4 minutes and only when it was started from dead cold. Once it is "fully" warm its fine, right where my targets should be. Ideas? is there a setting I dont know about that is adversely affecting things?

BTW the car pretty much stock and I am using an LC-1 with the "DB" gauge they sell with it. Feel free to tell me if my AFR targets are way off as well. I know the boost area is wrong but not needed yet.

And as you will ask here is a screen shot of both tables.

 

Your targets are lean at WOT IMO. Also, your fuel table could use some hand smoothing. it should constantly increase from bottom->top and left->right.
As far as the problem you experience with oscillation during warm up, it sounds to me like your AIT correction tables are off. I think that the defaults look at coolant temp for the correction. Let me see if I can find some helpful threads to redirect you to.

 

log it and watch the gammaeAE

 

I had that same issue for a while, but don't have it now and I'm not sure what I specifically did to fix it. Maybe just a whole bunch of logging and MLV'ing. Part of my trouble may have been related to MLV's tendency to overshoot on its recommended changes. If the cars runs even sort of okay, set the MLV analysis to hard or very hard, or you'll be playing a never ending game of rich-lean-rich-lean ping pong trying to tune your part throttle cells. I also agree with Jeff, for a N/A car you will be at ~100 kPa at WOT and you should target about 12.8-13.0 in that row.

 

Actually i had noticed that the MLV was doing a rich tune then a lean tune and just back and forth. I didn't realize that the tolerance for adjustment was adjustable in MLV I'll give that a shot.

I knew I was pushing it a bit with the WOT targets, but you guys really think I should bring it all the way back to 13? I had it at 13.5 for ages and it seemed to really like that. Just changed it to 13.9 last week and given that it is no faster really I was already thinking of going back.

 

Theoretically, NA cars make MBT at 13.5:1 afrs on gasoline. Once you get leaner than that, one of two things happen. You either:
a. Detonate if the fuel octane is too low/ you run too much timing. or
b. you lose power.

IIRC, most guys actually find that they make peak power running in the 12.5-13 :1 area.

 

Also have a look at the log, if your map deccel goes on - if you map threshold is set too low it will enable and pull fuel.

 

oh yeah, i forgot, turn off baro corrections. I win, game over, /thread, ?????, profit.

 

I agree with Jeff. I had the problem before and tuned it out with the IAT settings. Get rid of the coolant related air density and go with IAT, tune it and thank me and Jeff later. You can probably tune it out with the coolant as well, but IAT is better if you have your sensor in a good spot that doesn't heat soak like a bitch.

 

You should be agreeing with me...

Blaize, post your msq.

 

Right I have reset my AFR targets as per you guys advice. WOT is now 13.2 I went looking for AIT settings and found the "coolant related air density" menu. It was set to "Corrected" and "coolant corrected". I have reset the first one to "normal correction*^" which I presume turns it off (2nd window goes dark). Ran horrible after this, VERY lean, all the time. did 2 datalogs, one for 10 min, another for close to 40. After that it is running pretty sweet again. No idea until the morning if I actually changed anything regarding my original problem.

Feel free to explain in simpler terms what I turned off and what is is supposed to do.

You mention heat soak to the IAT, I had not been paying much attention to that input to be honest but I did today. My sensor is mounted to a steel length of pipe that is taking the place of the old flapper box. All sort of thrown together as it will be FI in the spring. Thing is that puts it in a steel pipe directly over the exhaust manifold. Today on the drive home it was 12 deg C. outside. at idle after a long wait (bumper to bumper traffic) it got as high as 54 deg. At steady speed, around 65mph for 10 min, it dropped to 25 deg. and again actual temp outside was close to 10 deg. all this sound feasible? I realise underhood temps will rise in stop and go traffic, but that much? Or am I chasing a red herring here and everybody gets this?

I didn't turn off baro correction Brain as I frankly couldn't find where to. It has however been set to pretty tight tolerances for quite some time. 102 and 96

and as requested here are a couple of MSQ. files By all means feel free to pick holes in them and tell me where I have/am going wrong. First one is what I was using when I started this thread, second is after today's events

 

Oh and thanks a ton for the help so far

 

To completely turn off corrections, turn it back to 'AIT related' but then go back in and zero out all the correction numbers in the table. I never really liked how the PNP map came with the correction values it did, but a stock miata sees such high intake temps it was almost required. Most of the time, I'll setup a table completely zeroed out, but only adding in enrichments for intake temperatures over 90*F to prevent it from going lean on hot-starts when the sensor heatsoaks.


Does your MS have barometer correction? I'm assuming no because 250MAP is set. Go to basic settings, then engine constants. Turn barometric corrections off.

You're welcome.

 

Right I'll try all that on the drive home tonight. Found it all and have done as told. I presume that to "zero out" the figures I set them to 100 ie normal fueling?

 

correct.

 

well it is much better. with the iat correction off it now slowly goes lean sitting at idle as that sensor warms up so i have relocated the sensor to right next to the t-body and i'll see what happens tomorrow. thanks for all the help guys.

 

anywhere inside the engine bay will heat soak. especially when the fans come on, so now you can tune the air corrections better.

did you turn off baro?

 

yep turned off baro. now reading the manual to figure out wtf the air corrections are and how they should work.

 

You're welcome. Air correction is to adjust the fuel based on the temperature of the air. Hotter air has less oxygen in it and therefor makes your car run richer if it's not taken into account. Cooler air does the opposite and you can run lean if it gets too cold without correction. That adjustment is to mitigate some of the heatsoak so you don't go lean in traffic. If you're slowly going lean, you can put a couple percent at the temperatures it's going lean at to help. The correction only occurs under like 2000rpm by default, so basically if you're moving, it's not used.

Edit: and good job on changing the location of the IAT. Over the exhaust is a horrible place for it. Near the TB is good and will have minimal soak compared to what it was before.

 

Glad that worked out for ya . Its always an adventure diving into megasquirt, but the payoff is worth it!