tfbmiata

Hey all, I recently installed my boost controller and while the first night in tuning in open loop mode I didn't seem to have any issues, and going out the last couple of times to tweak out exactly what I want I noticed that each time after warming up the car from cold the boost controller seems to require a much lower duty cycle to hit the same peak boost and then after a while of being warm suddenly that will inverse and my previous duty cycles seem to work again. Has anyone else experienced anything like this? It's really annoying because I don't want to hit boost cut constantly which I have set a few PSI above where I want to be for my actual max boost. Thanks

tfbmiata

Anyone?

I noticed again today that I had to sit and idle for a bit after driving around to warm up, then the open loop duty cycle seems to work before that I just run into boost cut repeatedly.

curly

iTrader: (25)

This is normal behavior. On my Link, I have trim tables for coolant, air temp, and gear (and anything else I put in a general purpose table). They all trim 2-100% duty cycle depending on the conditions.

In colder air temps, you'll hit boost targets with much lower DC. Why you can't trim for CLT/AIT is a big gripe of mine.

If you're MS2, wire a switch inline with the signal line, and turn it off in colder temps, running only wastegate.

If you're MS3, you have a few more options with CL boost control, such as lower CLT threshold, soften up the bias table, table switching, etc, or you can do the same inline switch.

tfbmiata

Thanks for the response cury! I do have an MS3. I haven't done any of the closed loop stuff b/c i can't seem to find a good guide on it. I started out trying to do boost by gear w/ kpa limits, but that didn't seem to actually work at all. One open loop tuning video i found mentioned closed loop doesn't work well until you have a decent duty table which I, at the time, had everything on 0. Is this possibly the cause of boost by gear seemingly not working?

As for this issue, that is crazy annoying b/c I'm like 5psi higher until boost cut while 'cold.' I did want to add that after sitting and idling for a bit, I hopped out and used my infrared thermometer on the EBC and noticed it was up to 175F. I know it says to keep it at 120F, does that have a major impact? I suppose I could move it, but I already thought I had it pretty far out of the way (it's by the driver's side fend bump where the diagnostic port is).

mrfattbill

While it may not apply I thing it's worth mentioning that when I was having mine remote tuned (MS3Pro & Flyin Miata kit) we were having issues dialing in the EBC and ultimately discovered that if you have any washers between the waste gate actuator and it's mount this can cause the EBC to be erratic.

Bill

Blkbrd69

What Link? Would love to compare tables.

I have the same problem with my Time Trial car. Hit boost cut on warmup lap consistently. Normal by hot lap but aggravating on street or warmup.

curly

iTrader: (25)

G4X pnp. I'm ashamed to say I'm still on open loop boost control, really need to dial in my CL settings. Despite having free dyno time available to me, three kids keeps my free time to a minimum.

For those of you without a Link, GP=general purpose. Any parameter you can think of can be assigned to X and Y axis. I randomly made it oil pressure and TPS to demonstrate trimming boost for low oil pressure, but my rev limiter protection would kick in way before boost cut did anything, so again, just an example.

You can see I trim 100% of duty cycle in first gear, so just wastegate to save the tires. I'm at 60% DC at WOT, so trimming 40% in 2nd gives me 20% DC, so probably close if not the same as wastegate.

RusMan

I have the same issues with boost control varying with temperature, very frustrating. Closed loop control is also very difficult/impossible to tune and can't compensate for temperature.
I'm thinking of switching to Link and this is one of the main reasons.

In the mean time I want to try getting a wastegate spring that's close to my target and maybe that would help. 12psi wastegate -> 14psi target.
I have a 5psi spring that I'm trying to control to 14psi.

RusMan

You mean the washer to pre-load the actual wastegate actuator/arm?
This is interesting, I think mine has at least one on there, interesting hypothesis to test I guess.

tfbmiata

My EBC is getting upwards of 180F and I know the site recommends no more than 120F. Right now its by the diagnostic port and after a while it just gets heak soaked. It seems the hotter it gets the less effect duty cycle has. I've noticed there's a spot near my power steering pump reservoir which is likely a better, less heatsoaked area that I'm hoping will have more consistent temperatures and thus open loop will have a better effect. I found the below information in the other thread at the top of this forum and if the location change for my EBC doesn't help, I'll be using it to see what I can do for PID control of the EBC. I will say this, I had 2 tuning shops both refuse to tune my car if it had at a megasquirt. Both just said some vague "issues" were why. Maybe this is one of them?

curly

iTrader: (25)

I guarantee you're not the first to have a temp over 120 degrees. I run an EFR solenoid and it's mounted directly to the compressor housing. There are kits out there to mount the MAC in the same place to an EFR turbo.

I'm almost 100% positive its a issue with boost control, not temp of the solenoid.

Try running the car on wastegate only. Log a full throttle pull from ~2000rpm to redline in 3rd/4th (5-speed) or 4th/5th (6-speed) as soon as you're comfortable doing so after starting the car on a coldish day.

Then get it hot, like 30+ minutes of driving, and do the same pull. I bet your max MAP reading will be different between the two.

redursidae

@tfbmiata You could try to set bias duty to values that work when the car is up to temperature, find a delta that prevents most of the overshoot, and let the closed-loop PID make up for the rest. Curly's recommendation of a switch to turn off boost control is a good idea, and in MS3 there is a CLT threshold you can setup as well. Try 140 or 160 for that threshold. Those are unfortunately your only options in MS3 to control duty cycle based on CLT, and there is no IAT compensation. The latest firmware, 1.6, made some changes to closed-loop control but I haven't tried it yet to give any input.

That post you found with the video and meaning of PID is a great way to understand it. If you need someone to tune it for you, shoot me a DM.

As for the "issues" those shop mentioned, they'll have to tell you what they mean. MS3 does a great job of running a car, but there is certainly more to be desired in refinement and you have to set your expectation accordingly. Boost control and warmup are some of those areas that need refinement compared to Link and Haltech for instance.

mrfattbill

That is correct.

Bill

tfbmiata

Great advice. I tried to do that and made a new thread here: https://www.miataturbo.net/megasquir...issues-109418/ . So far I've only tested once but it seemed to work well. I'm going to be relocating my EBC to that gap between the firewall and cabin under the windshield as it is way cooler than the engine bay and hopefully the temperature delta and thus duty cycle swings will be marginal. Thanks for the advice on the other engine management systems and why. Perhaps that will be one day in the future when I have an idea what I'm doing better.

tfbmiata

Relocated tonight. Will report on temps when I get a chance to test in the next few days. Hopefully the net effect is a consistent temperature range which doesn't impact duty cycle settings in open or closed loop.

mrfattbill

Um....that looks like it is hooked up incorrectly. Port 2 goes to the wastegate actuator, port 3 goes to the turbo and port 1 is open to atmosphere.

Bill

tfbmiata

Its been working this way so I dont think so. I have a dual port external waste gate so I followed the setup here. I think you are referring to the single port internal wastegate setup. I was actually really curious if simply setting it up as a single port would have the same net effect only allow me to go beyond 14psi (double waste gate pressure which I think I'm limited to with the dual port design and 7psi spring).

https://www.diyautotune.com/wp-conte...id-768x872.png

Watterson02

https://www.diyautotune.com/product/...-solenoid-kit/

I missed that you have the dual port and already linked this post lol. I'm just going to leave this up so that the image is more visible I guess

tfbmiata

This was definitely the right move to control temperatures. 77F after over 90 minutes of tuning session probably two dozen redline pulls and ended the session with some hoonigan things on some back roads.