quixotic

Hi All. My 2002 is naturally aspirated with just the typical intake and exhaust improvements, and an MS3Pro.

My idle goes in and out of closed loop...but only if I either have the a/c or the defrost vent turned on. If I just have the floor vent or the dash vent on, the idle will stay in open loop (even if I specify closed loop in MS3), and the rpm's will be absolutely rock-steady, and the afr's right where they should be.

But if I put the defrost vent on (or a/c), there will be a steady oscillation, initially with about 5 seconds of closed loop, higher rpm's, and higher afr's, followed by about 20 seconds of the open loop and the rock-steady idle. Then it repeats, ad infinitum.

Right at the start of the closed loop, I can hear a click in the engine bay, and with a stethoscope, it seems to be coming from the a/c unit.

This behaviour occurs whether or not I tell the ECU to go open-loop or closed loop.

I watched the engine states indicator as this was going on. When the afr/rpm is rock steady, only the overrun button lights up. But when the spike occurs, CL idle on, idle, idle VE, and idle adv buttons all light up.

MS is version 3.1.04 and MS3 1.5.1 release. The megalog file I've attached shows the typical open/closed loop oscillation.

Any suggestions? (thanks in advance)

SpartanSV

Closed loop is being disabled because you're below the MAP threshold set in engine states. You're idling at 28 and the threshold is 30. Lower the threshold to something like 24 and see where you're at. You may have to do some additional tuning of closed loop idle after the change but you need to lower the threshold first so you aren't jumping in and out of closed loop.

quixotic

Thanks, but that didn't work. I also tried it with MAP threshold at 22, but the same thing happens with the afr/rpm spikes about every 20 seconds or so.

Should I try the MAP threshold at even lower values?

Is there any way to tell the ECU to stay in open-loop? I can set the Idle Control Algorithm to "open-loop (warmup)", but the ECU just ignores that (I suppose probably because I'm no longer in warm-up).

deezums

iTrader: (3)

Then you either have a broken megasquirt or you need to read the manual, because that's not how it works or was ever supposed to work.

I assure you it will be a million times more efficient than posting a million novice level questions here.

SpartanSV

Fresh log and updated tune please.

quixotic

Here you go. I put the min kpa down to 20, but it didn't seem to have made a difference.

SpartanSV

It did exactly what I said it would. You're in closed loop idle that entire log.

These tables are your next problem. An engine needs different fueling/spark timing depending on the load and engine speed. Setting everything to the same number is how you make a car run like garbage.

quixotic

OK, thanks. It's my understanding (from watching Evan's Performance Academy) that adjusting spark is a better option than adjusting VE because the former is faster at feedback.

So should I be adjusting the idle advance settings? Or the idle rpm timing correction curve? Or the spark table? (I'd like to reduce that variables a bit if I can, so if I can turn something off, that would be great).

For VE, can I turn off the idle VE table and just concentrate on the main VE table?

SpartanSV

I would recommend you turn off idle VE. Your main VE table needs work and your spark table is very very bad. I would highly recommend you revert to a spark table from a reliable basemap then don't touch it until you know what you're doing.

LeoNA

It has been recommended that you tune your timing and ve table already on m.net.

What is the advantage of having the idle advance on and all of the timing values are set at 10 degrees. Either turn it off or tune it. 10/30, 10/35, 15/42, 18/50 might be a good start. The button on the upper right will show you the values for the graph which makes it less difficult to change the curve. See the idle advance pic. Under ac idle up there is a setting for the load idle up cl allowance % your at 15 currently try 20.

quixotic

Thanks folks. I'll disable Idle VE, and I'll try the a/c load up allowance at 20%.

I've attached the base map imagery for the spark stuff. So I'll try something closer to its (or LeoNA's) advance timing. For the main spark table, I'll increase the timing for the 1,500 rpm column to better match the base map. I previously reduced the timing at 950 and 1200 rpm, on the understanding that 10 degrees will give more wiggle room than 19 degrees.

Unfortunately, I sometimes try isolated elements from other people's success stories, while not really understanding what I'm doing (see the last post here, for example:https://www.miataturbo.net/mspnp-55/...n-table-92130/ )

SpartanSV

That spark table is still awful and potentially dangerous IMO.

LeoNA

The timing table is not good. First adjust your x&y values for your application, use the double arrow in the lower left corner. If your na you don't need to go above 110kpa. I also like to have a specific column for my idle rpm. Your timing has to match your AFR table to some degree. The 3 main areas are the idle & off idle, lean cruise and power (90-100kpa).

Jamikins

iTrader: (1)

My suggestion is to start with a DIY Autotune map, and scale it for boost. I haven't been doing this very long, and even I can see that your fuel and spark maps need work.

I bought my MS3 Pro last year, and have spent probably 50+ hours over the summer researching, testing, and tuning my maps (I probably have 20 hours in idle/startup alone). My laptop travels with me all the time.

There are a lot of great posts in this site that will provide you with all you need. Do your homework, understand the needs of your engine at various KPA/RPM's, and adjust.

quixotic

Your reply is potentially dangerous if you're not going to tell me how the spark table is potentially dangerous.

DNMakinson

iTrader: (3)

Go to Trubokitty.com and download the base msq for your model year / ECU. It is for a DIY, rather than Pro, but the spark table is what you are after. It will be conservative and then you can build from there.

You can also use other settings as rough planning. Likely 1.4.X based for MS3. Again, most settings will still be OK for 1.5.1.

DIY base maps do not pertain to Miata.

SpartanSV

Holy **** dude I already told you how to fix it and you ignored my advise. Two others have since made the same suggestion.

I'm not going to take the time to pick away at your table explaining why each area sucks. Download a good tune and compare your table yourself. I like the ones found on www.trubokitty.com.

LeoNA

This is getting a little out of hand. The OP needs to learn how to tune or take it to someone who does. There is nothing wrong with learning but it takes time and the actual work at hand is maybe only an hour to get 90%+ correct.

No one wants to outright give you a tune because they don't know your specific vehicle and its idiosyncrasies. I gave you an example of what the start of an ignition map should approximately look like.

Jamikins read the OP's first post he is not boosted so he does not need to scale for boost.

quixotic

Got it. Thanks. Looks like a 10 degree trough at 800 and 1,000 rpm, with significant advance increase at 1,500 rpm. I see that the idle advance table is turned off, but the timing correction curve is on. Do you have any advice on whether I should be using either of those or neither?

DNMakinson

iTrader: (3)

Scott has that set up correctly. Exactly what I do.

EDIT: Actually, I lied. I do use an idle advance table, mostly set at 10*, whereas the areas in my normal Ignition Table are in the neighborhood of 15*.

That way, I get an instant jump in advance when the throttle is pressed, and the car goes out of idle.

I don't know if it really helps, but that is what I have right now.