[LNF SS/TC] - Stock Internal & BW S252 Turbo

[Mayor West]

Took it for a 30min spin today. Adding 1.44x on the MAF makes it idle, not 100% perfect but decent enough to call it idling.

I'm not entirely sure I understand how to tell if I need additional adjustments to the MAF main freq +/- regarding the new placement of the MAF and the fact that it's blow through. To know if the scaling is good enough to start doing ST/LT fuel trims.

Should the idle Hertz be in a specific area or something?

Other than that it's incredibly twitchy at low throttle. Sometimes hard to look like I know how to drive a manual which is obviously a blow to my awesome manly ego, lol.

Anyway, progress is progress.

 

[ctuinstra]

It's time you work on tuning it in. Don't get too wrapped up in how much to move the numbers up or down, tuning will tell you that. There is not specific hertz setting for idle, every Goblin is going to be different when tuned.

Once you get it tuned and many other things fine-tuned, the throttle will be a lot more smooth. Our car was set too stiff in the compression of the QA1 in the front and that made the car bounce hard on every little bump which in turned caused my leg to bounce and I could not control the throttle for crap. Softening the compression made a world of difference to make the car ride smooth and in turn smooth out the throttle. In addition, do NOT disable the torque control, at least not while tuning.

When tuning the MAF, you want slow and steady throttle changes, not quick and sudden changes. You may even be able to tune the idle and just off idle while in the driveway and in neutral.

 

[Ross]

Took it for a 30min spin today. Adding 1.44x on the MAF makes it idle, not 100% perfect but decent enough to call it idling.

I'm not entirely sure I understand how to tell if I need additional adjustments to the MAF main freq +/- regarding the new placement of the MAF and the fact that it's blow through. To know if the scaling is good enough to start doing ST/LT fuel trims.

Should the idle Hertz be in a specific area or something?

Other than that it's incredibly twitchy at low throttle. Sometimes hard to look like I know how to drive a manual which is obviously a blow to my awesome manly ego, lol.

Anyway, progress is progress.

To do MAF (mass air flow) tuning, you are going to need to set up VCM Scanner tool and the VCM Editor tool for your engine.
The high level concept to MAF tuning is:
- When the engine is up to temperature and running, use the Scanner tool to log the wideband's observed AFR (air fuel ratio), compared to the ECM's requested air fuel ratio. The difference between these two is the AFR error.
- Once the error is collected from a test run (driving 5-15 miles, or maybe just near idle in the beginning), then you apply an error correction to the ECM MAF table, based upon the AFR errors collected.

Here is a VCM Scanner log file of mine.
The left window has the parameters that I was logging. The highlighted line is my AEM wideband, showing a .96 lambda at the moment. 2 lines above that is the AFR commanded by the ECM, which is 14.70 at the moment. 14.7:1 is equal to 1.00 lambda, so my engine is running 4% rich in AFR at this moment.
The top right window has a chart of the collected AFR errors, broken down by the closest Hz reading from the MAF sensor.
The highlighted cell is showing -7.3% error (running rich AFR) at 3600 Hz MAF frequency. This is my average error at that frequency during this test run.

What you need to do to start MAF tuning:
- Connect the MPVI to the OBDII port, and your laptop, with VCM Scanner running. Does the software connect to your car? Can you start logging data?
- Add your wideband to the parameters on the left that are being logged. Also add the AFR Commanded by the ECM. Maybe some other useful info, like RPM, Throttle position, speed, etc. Try to keep it under 20 parameters logging, so it doesn't get too slow at logging data. Can you find your wideband O2 sensor? Is it showing valid data? (mine needed to be divided by 10 to get lambda)

After you get thru these first steps, we can talk about setting up VCM Scanner math parameters for calculating error percentages, and VCM Editor stuff to put the engine in open loop and settings for MAF tuning.
Do me a favor, and tell me where you are currently. Have you installed VCM Scanner software on a laptop?

 

[Mayor West]

Yes I've been scanning and have all my parameters set up, wideband included. My last scan was about 30 minutes long.

 

[Ross]

Have you been logging the AFR error percentages?
Have you put the ECM in open loop with the settings for MAF tuning?
Have you applied AFR error corrections to your MAF table?

 

[Mayor West]

For all but open loop, I believe so, terminology is not something I'm 100% familiar with in terms of HPTuners but I've got @OptimizePrime setup and config from his tuning section. We're IRL friends so he's shown me the basics in person as far as getting set up.

I have MAF base correction, MAF hz ST/LT trims, KR, Boost, retard/advance, and AFR in lambda.

As far as open loop, I'm not 100% sure so probably not. I followed goat rope garages suggestions on how to go open loop but I can't apply half his trucks settings to my setup.

I'm putting the kids to bed, I can upload my current tune and latest scan later if it'd be helpful to get an idea of what I'm working with.

 

[Ross]

Oh good, you have tuning support.
You are a lot farther along than I realized.
Feel free to reach out if you are stuck, or when you have questions.
Watch your wideband while driving, and be sure not to run the engine too lean before it gets a proper tune.
You wouldn't want to kill the engine during your first few runs.

 

[Mayor West]

I'm not sure I know how to get into open loop, or if I'm already in it? Can you fill me in on that gap? Goat Rope had a bunch of options that I don't see and DFCO is confusing on this in comparison to his.

The times I was watching my lambda it ranged from .7 at higher load and to 1 closer to idle, but rarely went over 1.06 near idle. I set my base maf correction to 1 so I expected it to be rich.

I haven't goosed it yet, biggest boost I've seen is 3lbs or so, so I'm mostly in vacuum in low load just putting miles on it.

Can you share your param/PID section so I can compare it to what I have, too?

 

[ctuinstra]

There is a PID that specifically shows whether you are in open or closed loop. This is good to make sure and monitor when you are. If I was around mu HP Tuners, I'd direct you to it.

You must be watching the wrong videos, he has some that are almost identical to our P12. I have notes typed up on how to set up for VE and MAF so I can refer back to it and make sure I don't forget any.

 

[Mayor West]

There is a PID that specifically shows whether you are in open or closed loop. This is good to make sure and monitor when you are. If I was around mu HP Tuners, I'd direct you to it.

You must be watching the wrong videos, he has some that are almost identical to our P12. I have notes typed up on how to set up for VE and MAF so I can refer back to it and make sure I don't forget any.

He's got a lot of videos around MAF tuning so it's a little overwhelming, do you happen to know which ones those were or know what key word I can look for? The ones I've watched are his basic MAF tuning series plus a few random others ones, but they're all in his truck and it seems a good bit different.

Also, my front springs are turned up all the way for this run and I can see how it was a lot less jumpy than my previous neighborhood runs where I had them set much softer, I'll set it lower... thanks for the suggestion.

 

[ctuinstra]

I went back to look for the videos that I followed but I can't find them after a year or more. I see what you are saying and his being different. As long as you follow the GEN 3 labeled videos, that should get you really close. When I can get to my computer, I'll send you my notes on the settings I use for each tuning. That will help a lot.

 

[Anks329]

I went back to look for the videos that I followed but I can't find them after a year or more. I see what you are saying and his being different. As long as you follow the GEN 3 labeled videos, that should get you really close. When I can get to my computer, I'll send you my notes on the settings I use for each tuning. That will help a lot.

These notes would be really helpful!

 

[Ross]

Mayor West,
We talk about PID lists in this thread.
Glad you are watching the AFR while you learn your modified engine, and keeping it safe.
Tuning will really wake this engine up, and make it happy and safer.

 

[Mayor West]

Thanks Ross!!! I'll take those PIDs and slap them in.
Chad, those notes would be a lifesaver.

If anyone has a pro-tip on getting the LNF into and out of closed/open loop I'd appreciate the leg up. I've googled a little bit and all the ecotec folks seem to disagree on DFCO settings.

 

[Ross]

I zero out my STFT, short term fuel trims, and my LTFT, long term fuel trims, when I am tuning.
If those parameters are changing from 0, then I am in closed loop, and I need to fix that for tuning.
Kyle changed multiple places to put an engine in open loop, but it should only require one place.
That is why you get various ways to put it in open loop. Some tuners modify 5 places, some 7 places, but it only takes one place.

DFCO, deceleration fuel cut off, when active, will stop fuel going to the engine when the throttle is off. This shows up on the wideband gauge as very lean condition, and collecting that data in your tuning logs will collect bad data. Watch your wideband gauge when collecting tuning data, and you can tell if you have successfully turned off DFCO.

A few mistakes I did when learning to collect tuning data:
Bouncing the engine off of the red line RPM limiter will also collect bad data.
Turning on the data collection logging before the engine is up to full temperature will also collect bad data.

 

[Mayor West]

I'm having a hard time finding out where DFCO is disabled in HPTuners for the LNF....

I've read a good bit and one or two posts mention setting the Torque Management > General > Tq Mgt Inj Disable > last column from 15 to 0 to disable DFCO... but I have little evidence to back this up other than a very limited result set from googling.

The Fuel > Cutoff / DFCO section for the LNF only has RPM cutout, not deacceleration. like the tab title says. (It's all RPM based cutoff)

Regarding forcing Open Loop, I'm only seeing info on the LSJ - not the LNF.... so I'm not 100% sure where to go about setting this for the LNF. Open Loop is no O2, but I don't see anywhere in the editor to change O2 settings except heating on/off.

 

[Ross]

I found the same thing that you found. The LNF has the Bosch E69 ECU, and it is quite different from my LSJ P12 ECM.
Not sure if anyone here has experience tuning this.

What Ive gathered for the LNF ECM doesnt have the traditional settings for DFCO.
Under torque management - ETC Limits - tq man inj disable is what i found that controls DFCO
Set to 0 to disable cylinder cut.

To test if this actually works on your engine, look at your wideband gauge when you are decelerating. If it goes very lean, then DFCO is still active.
If the wideband gauge stays near 1.0 lambda, then you have disabled DFCO. Success!

If you can't succeed in disabling DFCO, you could filter your logged data, and throw away any data collected when throttle is less than 25%. The remaining data could be used for tuning.

Open loop is when my P12 ECU is not modifying the STFT and LTFT (fuel trims) when the engine is running. So if you see the STFT changing, you are in closed loop, and not able to gather the data needed for tuning.

As far as open loop control in the LNF, forget it, there is none. There are obviously open loop control tables somewhere hidden in the ecm, however none of which can fully be controlled through hp tuners at this point. There is a bit of a work around to that, but it's quite honestly best to just stay clear of it at this point. Regardless, the LNF actually does not enter into open loop at WOT (with some exception). The controller is setup from the factory with a built in wideband sensor so all fuel and PE control can be utilized and monitored while still in closed loop and again adjusted/tweaked through fuel trim corrections.

 

[Mayor West]

Thanks for re-confirming my LNF suspicions. There's a great deal of LSJ info out there but the LNF appears to be a void of good info.

Since it has a factory wideband, that makes the need for open loop disabling of the narrowband sensor needless, you're saying?

I've made some changes to the torque management table by RPM to lessen the available torque in 1st and reverse to around 20-25%. I'm going to soften up my front coil overs, as well, and try disabling DFCO with 15->0 changes and go for a spin this week.

The weather's supposed to be nice so hopefully I can get some good miles in.

 

[Ross]

The purpose of disabling closed loop is to log the air fuel errors.
In closed loop, the ECM is correcting the errors (using the STFT and LTFT fuel trims), preventing us from logging the errors.
Once we know the errors, we correct the ECM tables, then the ECM can accurately calculate the fuel needed.

If I owned an LNF, I would still try tuning.
After I make a small change to the engine, I would watch my wideband gauge, and see if the engine is running better or worse.
You can always go back to the previous tune if it is running worse.
Keep researching, as there are tuners out there who have figured out the Bosch ECU.

This guy posted a tune for an upgraded BNR Turbo. Compare his tune to your tune, and learn what he changed to accommodate the turbo.

2008 Chevrolet Cobalt
Engine: 2.0 L4 - Manual
Submitted By: Jamon of Colletti motorsports

08 Chevy Cobalt SS
BNR Turbo upgrade
3" downpipe
no cat
injen hardpipes 20 psi
mild timing
no traction control
11.5:! afr boost
runs good
starting point for bnr

 

[Gtstorey]

Many of you may have already seen this, and I don't know enough about tuning to know if it's useful, but here are a couple of links on tuning the LNF.

LNF Tune's Guide | Chevy Cobalt Forum (yourcobalt.com)
LNF Guides (hptuners.com)