So I was gonna do a low net gain turbo setup on a D15. Neptune seems user friendly and not too bad on cost so that's the route I plan on going for management.
I'm not afraid by any stretch to set up a street tune, my only issue is I live in a small town about 4 hrs north of Vegas, way up in the mountains. 6500 foot elevation,
and obviously that's where I'll do the most driving. If I take it down to Vegas for a dyno tune, running open loop, (which I'd like to), I feel like the elevation difference would
play havoc on my AFR's. Any ideas to counter this, should I run open loop? This stuff is still a little ways down the road for me, I haven't started calling shops in Vegas to
see who tunes on Neptune, or whether they prefer tuning in open loop or what.

 

Proper tuning must be done in open loop. There isn't a perfect solution to the problem that you have when using a narrow band O2 sensor and conventional closed loop operation. I suggest you speak to the tuner in Vegas about tuning the car with a wideband O2 sensor and keeping the car in closed loop all of the time... even at WOT. This can be done with A/F target values.

 

This confused me a little bit,
You mean as in when the car is in the process of being tuned, to prevent the ECU fighting with you while you adjust fuel tables? If so I'm aware of that, and that's what I meant as far as the actual process of tuning is concerned.
But I mean after the fact, disabling open loop operation, and running in closed loop ALWAYS, running on your preset tables, including idle/warm up tables, etc.
The ECU will still have enough range of adjustment, in a permanent closed loop state, to compensate for the altitude changes? Maybe I was underestimating how far the ECU will trim on your fueling tables to reach target A/F. Am I misunderstanding the mechanics at work here?

Also, yeah I know the wideband is necessary.

 

I just realized my mistake, I said "running open loop" instead of closed loop, my bad

 

The Barometric Pressure sensor only takes a reading for global compensation when you "key on" and start the car for the first time... it does not function in real time, so this would not alter the fuel delivery as the altitude changes during your drive. Also, the Baro correction is fixed, so if you install larger fuel injectors, the correction will be skewed and unfortunately magnified.

 

I'm running Neptune currently and a few pointers to follow.. There is information I found in regards to elevation changes, I will see if I have time to dig those up for ya today..
open/closed loop.. You'll never run full time closed loop and if you do, you won't be happy at all. Closed loop is good for cruising and retaining as much fuel economy as you can after you've dialed in your actual tune, that's it. I had mine set on full time and ran like **** until I figured it out. Lol. Had another member point me in the direction I SHOULD have gone to begin with and she's now running like a scalded cat and I'm back up to a friendlier fuel economy.. A properly set up closed loop will deactivate under your set conditions, engine load, tps input, etc... then go back on under set or met condotions.. you can run full time open loop with only minor setbacks; fuel economy and emissions being the largest.. There's not MUCH worry about the little things as far as tweaking your tune for weather that I have discovered and I live in the south; humidity and temps change on a dime, particularly between seasons and summers are like saunas; hot and humid..

 

Well, fortunately there, since I'm gonna be running such a small amount of boost, I don't think I'll have to order anything huge as far as injectors. Is there any way you could PM me a little more info on Baro function? Iirc Neptune has quite a few voltage offset settings, so I feel like there has to be a way to dial that in.

 

Okay, but this is kind of another point of confusion to me. Given that you tune fuel and spark on three different planes, being load: maf/map, throttle position, and AFR, all of those parameters give you the full range of control over any driving condition, or so I thought? By that logic, if your car ever ran like ****, at idle, cruise, WOT, whatever, it's because you didn't refine a certain area correctly, you know what I mean? You go back, refine that area of your tables, and eventually you'll work out all the kinks. Like why at that point would I want my car to run on anything but the tables I so meticulously laid out?

I know there's just a little bit of info that'll flip the great switch of understanding, I just need to know what it is. Haha.

 

I do know that a lot of the confusion has a lot to do with the sheer number of conflicting opinions I've read on different forums over the last week or so:
"You shouldn't ever run open loop."
"You shouldn't ever NOT run open loop."
"I don't even know how any of this works just let your tuner worry about it all.
And everything in between.

 

It was recently put into perspective for myself.. Begin your tune in open loop to get as close to, if not dead on your target a/f settings, then enable closed loop and you can let the ecu do the grunt work. I got dialed into about +/- 3% or so of my target (open loop) on fewer than 15 cells, then enabled my closed loop again and it runs beautifully. I am still learning myself though and it has taken me several maps; configurations and adjustments, to get to a good starter tune. Lol

 

What parameters do you use for open loop/closed loop crossover? Like standard open loop at warm up and WOT? Or does your tune ever switch to open loop?

 

I'll take a snap of my CL settings for ya and get them here. Gotta charge the laptop. Lol

 

There ya go. This is where it is as of now. I'm still in the process of watching my daily commute data logs to study tps positions so I may adjust that particular area later but for now, it's doing alright. Most of my commute is spent under 700mbar with a few areas I can stretch her legs to go over that. So it's a good start.
if you're boosting, you may need different settings.

 

Sweet man, I appreciate you taking the time to do that. So yeah, generally for warm up, and 5k to redline. Probably not even idle? Unless you idle at 500 rpm. Only thing I don't understand there is the invert setting, I'll have to look into that more.

 

invert is for wideband. If you're running a wideband o2 sensor, that should be checked. Stock o2 sensors work opposite to widebands; the lower voltage on a stock sensor indicates lean, higher is rich. That is not the way wideband operates. The lower voltage indicates rich; higher lean. So if you're running WB, invert should be checked so it is reading right.