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Premium Member
2015 Cruze LT 1.4, aka Yuffie, aka RecklessRed
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289 Posts
Discussion Starter #1 (Edited)
I will preface this with saying that I am by no means an expert. A LOT of reading and trial/error have gone into what I have learned, so if there are errors, please don't be a **** about it, but for sure post in the thread so we can clear it up.

The VVE tables (Virtual Volumetric Efficiency) are interesting. They are not the same as the older VE tables in previous computers, but more of an abstraction to calculate data for the SD coefficient tables. SD (speed density) is essentially a way of measuring the air coming into the engine sans MAF. The MAF reads incoming air by a heated wire and the voltage it reads (or rather: it wants to maintain a certain level of heat, and to do that, requires electricity; more specifically the frequency of the electricity being conducted. As the air blowing by cools the hot wire, the computer has to turn up the frequency of the voltage, basically "forcing more pressure through the pipe" (electricity behaves very much like water in that sense) to maintain the flow of current (electricity or water.. they are not dissimilar in that way. The freq. measured has to be calibrated like any other precision measuring device. Sorry about the late edit. I just find it interesting.). As cold air moves over the wire, it cools down, changing the voltage (refer to above-aside parenthetical), which in turn gets sent to the ECM and converted into airflow (in lbs/s, I believe).

To get more technical, the wire that the air passes over is part of a large oscillating circuit. The wire is warmed, then subsequently cooled by air, changing it's inductance, hence the difference in frequency that the ECM uses to calculate the airmass based on the arbitrary correlation between the programmed airmass v MAF freq table (which is why if you modify it, move it, make it bigger, etc, you will need to calibrate the MAF.). source: https://www.camaro5.com/forums/showthread.php?t=185592&highlight=Tutorial:+pcm+sets+fueling (bluetorp)

SD works without this, judging it by the absolute pressure in the manifold and the temperature of the air inside of it. From what I have read, the MAF is "disabled from the factory", but it still reads and sends that data to the computer. SD will kick in completely in case the MAF fails for any reason.

The general idea for this is to tune your car to run completely without the MAF (it still has to to be hooked up, as it contains an IAT sensor in it, but the actual mass airflow data will not be used to calculate airflow as a whole).

Tuning for this can be a little time consuming, and you should have a working knowledge of your car, tuning, HP Tuners hardware/software, etc before even attempting to do this. I am not going to put the stupid disclaimer up that says do this at your own risk. If you are reading this, you know what can happen, and go ahead and try to sue/blame me if you pop your motor or something... good luck. haha. ;)

With all that, this is what is working for me from what I have learned. Take it or leave it.

Let's get to it.

NOTE: Before doing any of this, please make sure your car is running well. Nothing is worse for a tuner than someone wanting you to get more boom in their ride, only to have them bring it in with problems. Correct all boost leaks, check/clean or change your spark plugs (make sure they are gap'd properly too), tired are properly inflated, you have at least 91 octane in your tank and a healthy amount of fuel, etc.

Workflow summary for this is roughly as follows:

1. First and foremost, download your stock or whatever calibration you have and back it up. Google drive, dropbox, whatever. I usually upload to google drive and email it to myself. That way, no matter what, I can always go back.

2. After downloading and subsequently backing up your current running calibration, save as a new file. I tend to use the following name/folder scheme (use whatever you want). (TheFuzz is the name of my one-man performance crew. lol. Named after my late cat. Yuffie is my car's name.).

$HOME/TheFuzz/HP-Tuners/Yuffie/Tunes/2019/10/28/2019-10-28_TUNE_YUFFIE-SD-Calibration-v1.hpt

3. Disable MAF sensor and LTFT (long term fuel trims). These will skew your data (MAF) and/or take much longer to dial in (LTFT). Disable DCFO. Disable COT. DO NOT DISABLE PE!!, LEAVE TORQUE SETTINGS ALONE FOR NOW.

EDIT: So, you hear a LOT of people saying to disable PE when tuning. I did it because it was working for me... until it wasn't. PE is needed ON and set to where you want your car to start going rich at. Just because you are not at WOT does not mean that you cannot benefit from it. Perhaps you have a nice open exhaust, and torque set high in the lower areas... regardless, you are making way more power downlow in the RPM range, you have your boost set high, your boost ratio set to double every cycle, good chance you will be well about 4-7 psi, and likely on your way to double-digit numbers, and still running at stoich. I have absolutely noticed much better, happier Yuffie (my car) when setting PE to where my power starts kicking in, instead of trying to work around it. The torque and PE systems are very easy to work with once you understand how they work, and you can put the boost, fuel, and the rate at which both give you maximum salvation. I plan on getting into more detail maybe next week when I have a buddy roll with me to get photos, screenshots, etc). Regardless... leave PE on to whatever it is bone stock. It is there to protect your car. SD tune the car up until 3500 with very light driving, then wherever you want your PE EQ set to, do so, and find where you start really picking up boost even at part throttle. Set your PE to start kicking on there. You may be surprised to see that the car easily goes to 12 psi and up at part throttle when you get a lot of flow parts. Your VVE tables are very important, but you cannot tune (in my experience, the higher RPM/load areas without PE and VVE against one another. Again, I will get in to it all later, but the gist is: Where is PE kicking in, how much boost are you running at the point, what is your EQ CMD, vs actual? When you are starting to go high enough in boost or flowing enough air outside of something sane, set PE enable there and whatever else you are triggering it with (pedal, tq, etc) and tune your VVE like that. All it is doing (PE tables) is setting your desired AFR, so you are the one that should decide on what ratio is right and user accordingly.

NOTE: You also need to make sure that the MIL still gets set. If you stop the error from hitting the computer, the MAF will NOT turn off. If you are like me and hate seeing the CEL/MIL then set SES (checked) and "No MIL Light" but leave it to "MIL on first error so that you know it's failed (check the DTCs in Scanner to make sure there is a MAF error. No error, and it's still active). If you set "No Error Reported" then the error will not get registered with the ECM, and the MAF will still be in the mix. Set the following in Editor:

  • You need to set the high RPM disable to something unrealistic. If it never hits that, it will not be used.
  • Set the MAF fail freq to impossible settings. This will make sure that it's off.
  • Setting the min ECT enable to something unrealistic will never let LTFT kick in. If it does with this set, your engine is likely f***ed. haha ;)
  • Disabling DFCO (Deceleration Fuel Cut Off) will help to not skew your results when logging. It will make huge lean spikes show up in the incumbent cells.
  • Disabling COT (Catalyst over-temp) will do the same as disabling DFCO except it will pollute your data with rich readings,
NOTE: COT dumps extra fuel in to cool off your catalytic converters. If you don't have them, I won't tell, and don't worry. If you do, this could, if run a lot like this, f*** up your cats. Stand warned. :)
- Disabling PE (Power Enrichment) will stop the juice from kicking in. This is not needed at this time and will skew your VE data if you happen to get into PE.
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4. Set up VCM Scanner channels to log a bunch of stuff (graphs, layout, and channel config uploaded to this post. :) ), and graphs to get the data you need. The row and column axis labels need to match the tables in Editor that we will be using this data on. If for some reason you need to change them because they don't match your calibration's tables in Editor, you can read the docs on how to copy the labels and create your own graph in Scanner so that the scalars match. This is INCREDIBLY important to get this accurate.

You also want to set up your VVE logging to do these three things:

  • Use an average for the cells. Not add, not highest, etc. Average
  • Set the minimum hits to 20-25 at least. 50 would be better if you are prepared for a long drive
  • Tell the graph not to log anything under 25% throttle
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If you don't do these, you won't get good data, and the rest will fall apart.

As for your KR graph, you can just use average for that. No other modifiers are needed. ANY knock is bad knock.

NOTE: MANY people turn off burst knock retard completely. I have not done it, but am planning on doing it this week to see how things go. I will post up my findings when I do. If you have already done so, please share your experience in the thread.

5. WAIT FOR YOUR CAR TO COME TO FULL OPERATING TEMP BEFORE STARTING LOG. With Scanner open, command closed loop, disable LTFT, and reset LTFT trims, then go for a long, *****-footed drive. No full throttle pulls, no hard transitions in pedal position. You need to drive it like you are my grandmother. Logging all of this, you will want to hit as many cells as you can in the STFT VVE scanner graph low/mid/high RPM range, all gears in different throttle positions. The more the better. You will also be monitoring for knock/KR/timing retard. This should be something you always look out for, but I feel like if I didn't mention it I would get railed.

6. After you get back home or park or whatever, stop the logger (stop button or space bar), and SAVE YOUR LOG. There is an autosave feature, but it's much more convenient to save before you even unplug your computer. Save like this (or however you want):

$HOME/TheFuzz/HP-Tuners/Yuffie/Logs/2019/10/28/2019-10-28_LOG_YUFFIE-SD-Calibration-v1.hpl

NOTE: Saving files like this will keep them grouped together and easy to find. Especially if you tune a lot, you will have a f*** ton of files to sift through. Being organized will save you in the end.

7. Copy (click top-left hand corner of table or CTRL-A to select all, then right-click, copy) all of the data from the STFT VVE graph in Scanner:

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- and open the VVE table in Editor and paste special, multiply by % (click top left corner of table or CTRL-A to select all, then right-click paste special-> multiply by %, or multiply % by half. It's up to you and how off your data vs. vve tables are).
NOTE: It will likely make your 3D VVE graph all sorts of spiky That is ok. We will smooth it out, but just for reference, this is the same one after I did the paste special multiply by %:

(Top: before, Bottom: After)

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8. Hand smooth out the peaks and valleys, click calculate coefficients. I do this by first selecting around the edges of the changed cells, selecting the changed ones, and the unchanged ones just next to it. Sometimes a little more, and using the smooth or interpolate button (I usually use smooth, but sometimes interpolate helps depending on what it is. Try both and see what works for you.) I gradually work my way around the outside and the stray cells off by their lonesome. then just start working your way in. Small groupings are better. If needed, you smooth out bigger sections towards the end, but don't do it too much, or the data you logged won't mean much.

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Copy all data from that table to every other table in the VVE screen (there should be four. When you do one, just copy, paste, calculate coeff. DO NOT paste special. Just make the 3 other tables match the first. Copy/Paste/Calculate Coeff will do that.

9. Go back to Scanner, and copy the KR table (top left corner click, right click, copy), then open up Engine -> Spark -> Advance -> Base -> High Octane. Select all (not going to repeat that again. Lol):

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Then right click, paste special, subtract. This will take whatever knock retard you logged and subtract those degrees from the base spark advance table. Ideally after a couple of logs/retunes, you should not see any more knock retard.
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10. Save calibration, reflash, and start your car. Check for anything funky (loping idle, explosions, kitten sounds, etc). Repeat process 2 or 3 times (or as many as needed) to alleviate any and all KR and get your VVE 3D graph nice and sexy smooth and curvy. You will notice that every time you do this, if done properly, you will get less and less big changes in your VVE table/graph, and start seeing less KR (until you see none). From what I have read, +-3-5% VVE difference from what your calibration has to what you see when you log is considered a solid SD tune. I could be wrong, but as of this morning, I did a REALLY long log since May (and have done a lot of mods since then) on the way to work, and it was getting very close to 7%. Probably only need another session or two to have it really dialed in.

So yeah, that is about it. It is not hard, but took a lot to find concise info, especially for our cars. I have read probably over a hundred articles, tutorials, watched videos, docs, etc. There was nothing super specific for us Cruzians, so I figured I would take the liberty and put it out there to help out other people. I have a LOT of experience tuning old-school hondas (Crome all day! haha), but they are radically different than newer cars, especially ones that are rockin this torque-based schema. I have yet to hit the dyno, but my car at 22psi with my mods, estimations are at about 170hp to the wheels. Again, estimations, but I have surprised a lot of people and have dusted quite a few cars that had their owners trippin that I did that in my car. And with this method, if you can keep your foot out of it, you can EASILY get over 40MPG and still have power to suit. I don't really care about numbers. I just want my DD to be fun. And it is. Very fun.

I will be posting up another one on how to up your boost and torque to make more power and how to adjust PE to kick in where you want it, but in my experience, starting here should be first. Then once you up your torque settings, you will want to do this again to account for the changes (on top of WOT tuning, which you absolutely will need a wideband to do safely). Literally every time you make airflow changes to your car, you will need to retune. Period. You will either not get any or very little power, or you will get driveability issues, or both.

I will also do remote tunes if you already own HP Tuners. I feel very confident in my methodology now with at least the Cruze and the Sonic (I have done 2 sonics and another cruze, and have had nothing but high-fives and smiles), and I don't charge much. Feel free to PM me if you are interested, but I do ask that if you have questions, PLEASE POST THEM PUBLICLY IN THE THREAD. This is a courtesy to those who are searching, so if they are looking for the answer to the questions you ask or the info you post, they can search for it and find it and keep all of our inboxes nice and tidy. :)

Thanks for reading, your support, and the "boost" I feel when interacting with the community. haha. Get it? Boost? turns to the left "Somebody write that down!"

-RD
 

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Premium Member
2015 Cruze LT 1.4, aka Yuffie, aka RecklessRed
Joined
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289 Posts
Discussion Starter #2 (Edited)
So, just a small update. After a bunch of logging. Gradually working my way up the RPM/MAP numbers to just before PE, my VVE graph now looks like this. Idle is fantastic, it drives great, no bogging or stuttering (well, a little but not much. Working on that too). Lots of power, but I still need to tune for WOT with my AEM wideband. I would really like to log it through serial, but I guess I will just do it through the AC pressure sensor.

NOTE: Obviously this still needs work, but I pretty sure the AFR err WB tuning will fix this. From what I understand, some bumps, hills etc are ok on a VVE table, because it represents multiple tables and zone and not all of them need to be smoothed in to perfectly. Please, correct me if I am wrong, though.
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As you can see, FAR smoother than before, and meaty where it needs to be. This does take time, but it can be done fairly well without a wideband. AGAIN, if you do want to really get your power and safety dialed in, you need to use a wideband, and don't let anyone say otherwise. You can get up there, but you want to be safe, so keep it sane, K?

I have also used the data logged in Scanner in regards to KR, and now have ZERO KR detected unless I am above 3800 and full throttle. Even then, it's only a degree or so, which I have logged and am going to tune out today.

I will continue to update this with whatever I find or do that may shed some light on doing this stuff.
 

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Way beyond me but props on one hell of a write-up!
 

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Premium Member
2015 Cruze LT 1.4, aka Yuffie, aka RecklessRed
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289 Posts
Discussion Starter #4
Way beyond me but props on one hell of a write-up!
Thanks! I got plenty more coming. Considering the lack of info for us cruzians and how few people actually respond, I almost didn't start posting things up. Now that I can see that people are finding it useful, I will be more diligent in posting findings. Usually detailed (probably too verbose for those more experienced.).
 

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So, just a small update. After a bunch of logging. Gradually working my way up the RPM/MAP numbers to just before PE, my VVE graph now looks like this. Idle is fantastic, it drives great, no bogging or stuttering (well, a little but not much. Working on that too). Lots of power, but I still need to tune for WOT with my AEM wideband. I would really like to log it through serial, but I guess I will just do it through the AC pressure sensor.

NOTE: Obviously this still needs work, but I pretty sure the AFR err WB tuning will fix this. From what I understand, some bumps, hills etc are ok on a VVE table, because it represents multiple tables and zone and not all of them need to be smoothed in to perfectly. Please, correct me if I am wrong, though.
View attachment 284225

As you can see, FAR smoother than before, and meaty where it needs to be. This does take time, but it can be done fairly well without a wideband. AGAIN, if you do want to really get your power and safety dialed in, you need to use a wideband, and don't let anyone say otherwise. You can get up there, but you want to be safe, so keep it sane, K?

I have also used the data logged in Scanner in regards to KR, and now have ZERO KR detected unless I am above 3800 and full throttle. Even then, it's only a degree or so, which I have logged and am going to tune out today.

I will continue to update this with whatever I find or do that may shed some light on doing this stuff.
Do you know your maf g/s reading at wot?
 
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