VE table tuning philosophy - need help

[Dan_the_C5_Man]

Ok - So I am in the middle / towards the end of my VE table tuning (them will move on to MAF, then PE).
I am using the guide, have my MAF, PE and LTFT's disabled, etc.

My question - if the idea is to tune all cells in the table to 14.7, err-

What happens with cold start idle (too lean)?

What happens when trying to tune on the upper end of the MAP range (high RPM + high load + 14.7 = not good)?

The other thing I’ve noticed is the stock VE table seems to be about 25% rich on the bottom (idle) and at least that much at the top end of the RPM range. - My setup is not radical at all - which makes me concerned / why would the factory programming be so far off?

I am questioning the methods here - maybe I don't understand the stated goals. For instance, if you were tuning a car to run purely in SD mode, would you really want everything to be 14.7 across the board?

Please help! Thanks.

[Gh0st]

1. Why are you disabling PE when tuning your VE? Strike one.
2. Sounds like you aren't using a wideband. Strike two.

I have no idea what your mods are. Typically when you put a cam in your car and change the VE, you're going to move the VE up in the RPM range. This means at around 2krpm and lower, you're going to have lower VE numbers. At some point the numbers will be "close" to stock and then the numbers will be much higher than stock. This is why you are 25% rich near your idle cells. Your top end should be too lean, but if you have PE disabled, I Hope you are NOT going close to your "top end" while trying to command a 14.7 AFR in OL....

No you do not want everything to be 14.7. The guides who tell you to put everything to 1.0 in the OLFA table are outdated. Leave everything past 170+ ect at 1.0 because you should really be tuning with a vehicle that is warmed up so you'll be at 1.0 anyways.

Sounds like you're reading off the incredibly bogus CPIG guide or something.

[Dan_the_C5_Man]

1. Why are you disabling PE when tuning your VE? Strike one.
2. Sounds like you aren't using a wideband. Strike two.

I have no idea what your mods are. Typically when you put a cam in your car and change the VE, you're going to move the VE up in the RPM range. This means at around 2krpm and lower, you're going to have lower VE numbers. At some point the numbers will be "close" to stock and then the numbers will be much higher than stock. This is why you are 25% rich near your idle cells. Your top end should be too lean, but if you have PE disabled, I Hope you are NOT going close to your "top end" while trying to command a 14.7 AFR in OL....

No you do not want everything to be 14.7. The guides who tell you to put everything to 1.0 in the OLFA table are outdated. Leave everything past 170+ ect at 1.0 because you should really be tuning with a vehicle that is warmed up so you'll be at 1.0 anyways.

Sounds like you're reading off the incredibly bogus CPIG guide or something.

Oh crap.. "Sounds like you're reading off the incredibly bogus CPIG guide or something" - yeah, that is EXACTLY the method I am using..

I do have a WB, and I have built the AFR % err PID - so I am logging the WB via my A/C input, works great.

You triggered something - maybe my PE is NOT disabled? Now I'll have to go back and look at the guide. And to that point, we really CAN'T tune the VE table in the higher MAP areas (w/o risk), correct?

Chrimeny - if that guide is "no good", why not pull it? Or at least give a noob like me a clue to not use it - So I assume the last 2 weeks of logging are all for naught? Please help!

[Gh0st]

Oh crap.. "Sounds like you're reading off the incredibly bogus CPIG guide or something" - yeah, that is EXACTLY the method I am using..

I do have a WB, and I have built the AFR % err PID - so I am logging the WB via my A/C input, works great.

You triggered something - maybe my PE is NOT disabled? Now I'll have to go back and look at the guide. And to that point, we really CAN'T tune the VE table in the higher MAP areas (w/o risk), correct?

Chrimeny - if that guide is "no good", why not pull it? Or at least give a newb like me a clue to not use it - So I assume the last 2 weeks of logging are all for naught? Please help!

Go to:

http://www.hptuners.com/help/

Working With VCM Editor > Tuning How To Section > User Submitted > Speed Density

Start here for figuring out the "proper" way to tune your car with a wideband. I'll edit this post with notes about this sometime tomorrow as I'm at work right now. I will also send you a PM with instructions on how to access an IRC chat where we discuss tuning daily

[EaglePerformance]

First off, we would need to know the car, mods etc. The VE table should be looked into next, then the maf. Ideally the VE table should be set so that the A/F is about 14.7, some of the zones require the engine to be loaded to the point that 14.7 is too lean, but if the commanded PE is say 12.5, then the VE should be adjusted till the A/F comes into line. The cold start is done with a different multiplier table. LOL, the last two weeks of logging aren't a waste, I'm sure there are things you learned.

[Dan_the_C5_Man]

Well, allow me to clarify - "wasted time" as in I have a finite amount of time to get the car tuned, basically 2 weeks - and that is with 10 hour work days and the wife and the kids.

So, what I need is a method (that is safe and is proven) to work from so I can get out there and log, update, call it good. I just don't have weeks or months to play with.

Perf. (motor) mods - 2000 C5 with Z06 injectors, LS6 intake and 243 (stock) heads, LPE GT2-3 (very, very mild cam - 118.5 LSA if that tells you anything), equal-length shorty headers, Z06 cats and Ti exhaust, home-made cold-air intake (stock lid, inverted), Vararam air bridge with 85mm MAF (relocates to just in front of TB).

Attached is a dyno run made before the heads and Vararam air bridge / MAF, with the IFR table scaled to match the stock Z06 injector profile and PE tuning by me, all other tables stock (besdies fans / CAGS, etc.) - keep in mind this is with 3.90 gears, so you'd need to add another 3% or so to compare with a stock geared car.


As soon as I installed the MAF / air bridge (using a stock MAF table from an 02 Z06), I saw my idle LTFT's jump to 20 - 25% positive (which I am not sure I understand - with my mods I basically have a stock 02+ Z06 motor, so why can't I use the stock MAF table from that model? Unless the MAF is broken (which I hope not), it may be partially due to the relocation / fluid dynamics of sitting right in front of the TB), which is what triggered this whole VE > MAF > PE tuning exercise.

Thanks in advance for any help / advice.

[Cantalope Kid]

Reccomend X 2

Go to:

http://www.hptuners.com/help/

Working With VCM Editor > Tuning How To Section > User Submitted > Speed Density

Just re-read this after several months of being a user. Its all there! This should be the first place we send anyone looking to learn how to tune their vehicle. It has a fairly simple step by step process on how to get your VE/MAF in line. PE adjustments are covered well enough in CPIG's guide for a DIY. There are some other tidying basics covered on the above link that I think all noobs should seek out as well.

[Frost]

Reccomend X 2

Go to:

http://www.hptuners.com/help/

Working With VCM Editor > Tuning How To Section > User Submitted > Speed Density

Just re-read this after several months of being a user. Its all there! This should be the first place we send anyone looking to learn how to tune their vehicle. It has a fairly simple step by step process on how to get your VE/MAF in line. PE adjustments are covered well enough in CPIG's guide for a DIY. There are some other tidying basics covered on the above link that I think all noobs should seek out as well.

Bill's profiles don't allow PMs so I'll just post it.

In that guide in the help, it mentions DFCO disable, but it needs to note that on M6 cars that the clutch fuel cutoff must be disabled as well...

[Dan_the_C5_Man]

Ok - thanks for the tips. Reviewing that guide, it looks like the CPIG guide I was using is a cut and paste from the HP Tuners version.

So, a couple of questions -

1. When measuring for AFR % error, IF I try to hit the high RPM / high load cells, we are saying that will put the car in PE mode, and the actual AFR error reported is the difference between the current commanded AFR (which would / should be, say 12.8), NOT the error / difference from 14.7? Is it valid to try and tune those high-load cells using this guide / method? I can check my scans, but I am wondering if the reason the VE table looked so rich on the top-end is because PE was kicking in, but then that goes back to my question - is it AFR error compared to 14.7 or the base + PE EQ? Could someone please clarify this?

2. On the low end / idle - should I be trying to adjust to 0% error with VE table scaling (I have to pull 25%+ percent to get it even close), or should I leave the stock values alone and do this in a table dedicated to idle tuning? If so, where is the best place to adjust idle parameters?

[Frost]

AFR % error is commanded AFR / Actual AFR (wideband)

[EaglePerformance]

For top end tuning, I believe commanded AFR would have to be base+ PE, good question, got me thinking, if the wide band readings are off, (assuming the WB is accurate), changes to get things right would have to be in the VE table to get the commanded, (base+PE) A/F correct. As far as idle, hmmm, I think I'll do some more reading!!
BTW, +1 on the "Kids" post, I reread that also. CPIGs guide kind of puts a lot of posts in one placel

[Dan_the_C5_Man]

Right - and think about it - how would you know exactly when you were in PE or not? If PE is kicking in while trying to tune the VE table, you'd end up leaning it out excessively on the top end , which is exactly why when I saw the "+25%" reading on my stock VE table (and I am making about 55 more HP than stock) - it doesn’t make sense. I am starting to think the entire VE table cannot be properly tuned via WB / road-tune methods.

The factory has dyno mules and fancy mathematic calculations to get around this, no doubt.

I hope I am making this more complicated than it really is; somebody with "the answer" please chime in.

[Frost]

Right - and think about it - how would you know exactly when you were in PE or not? If PE is kicking in while trying to tune the VE table, you'd end up leaning it out excessively on the top end , which is exactly why when I saw the "+25%" reading on my stock VE table (and I am making about 55 more HP than stock) - it doesn’t make sense. I am starting to think the entire VE table cannot be properly tuned via WB / road-tune methods.

The factory has dyno mules and fancy mathematic calculations to get around this, no doubt.

I hope I am making this more complicated than it really is; somebody with "the answer" please chime in.

you know when it 'kicks in' because commanded AFR switches from whatever you have commanded in the OLFA table to whatever is in the PE table and STFTs move to 0% and do not update.

It can absolutely and easily be tuned on the road with a wideband; you are a little mixed up.

[rwj383]

You have essencially 3 different WOT range fueling modifiers that have direct affect on your AFR at all times: PE Enrichment table, VE table (at the 95, 100, 105 kpa ranges) and OFLA table (at the same ranges as the VE table). More on that but first- You will also know ur in PE if your TPS% and MAP satisfies the PE Enabled table, alas you will be in cell 22/OL. At any rate, you can certainly tune your WOT/PE parameters utilizing the VE table, the numbers >95kpa MAP + your WOT RPM range you wish to tune will affect your AFR per your WB. I dont try to Paste Special the %err from the histogram scans to tune WOT PE AFR, I simply look at my WB scan recording results in the cells 95, 100, 105 (or more if you have 1 bar HPT + forced air) kpa readings throughout the RPM range I am tuning for my 12.8:1- 13.0:1 AFR for naturally aspirated WOT AFR. I make changes in those cells accordingly in my VE table in those cells. Leave the OLFA cells at 1.001 in all the wot range as well as your PE Enrichment table to 1.001 then simply tune your WOT AFR using the 95,100 and 105 kpa cells in the VE table. Using the VE table to tune your WOT along with Closed Loop part throttle SD tuning gives you a little more resolution to tune WOT AFR because instead of a single cell per RPM column to tune WOT (as you only get in the PE Enrichment table) you get 2-3 cells per RPM column to tune naturally apsirated WOT in the VE (95kpa, 100kpa, 105kpa cells per each RPM column). Remember to leave your OFLA at 1.001 in the WOT range and leave the PE Enrichment table alone, as well, at 1.001 as these are WOT modifiers at all times.

[rwj383]

You have essencially 3 different WOT range fueling modifiers that have direct affect on your AFR at all times: PE Enrichment (EQ Ratio vs RPM) table, VE table (at the 95, 100, 105 kpa ranges) and OFLA table (at the same ranges as the VE table). More on that but first- You will also know ur in PE if your TPS% and MAP satisfies the PE Enabled HOT/COLD tables, alas you will be in cell 22/OL (cell 22 = WOT, cell 21 is Idle/throttle closed, Cell 20 is decel, right? I might have a couple of these switched up, been a while ). If you still seem to be getting stoich AFRs when in WOT 100% TPS, try setting the other PE Enable parameters to 0 value (the MAP, MAP Hysteresis, Delay, Enable Torque, Torque hysteresis). At any rate, you can certainly tune your WOT/PE parameters utilizing the VE table, the numbers >95kpa MAP + your WOT RPM range you wish to tune will affect your AFR per your WB. I dont try to Paste Add/Subtract/Special the %err from the histogram scans to tune WOT AFR, I simply look at my WB scan recording results in the cells 95, 100, 105kpa (or more if you have 1 bar HPT + forced air) readings throughout the RPM range that I am tuning for my 12.8:1- 13.0:1 AFR for naturally aspirated WOT AFR. I make changes in those cells accordingly in my VE table in those cells. Leave the OLFA cells at 1.001 in all the wot range as well as your PE Enrichment table to 1.001 then simply tune your WOT AFR using the 95,100 and 105 kpa cells in the VE table. Using the VE table to tune your WOT as well as Closed Loop part throttle SD tuning gives you a little more resolution to tune WOT AFR because instead of a single cell per RPM column to tune WOT (as you only get in the PE Enrichment table) you get 2-3 cells per RPM column to tune naturally apsirated WOT in the VE (95kpa, 100kpa, 105kpa cells per each RPM column can affect your WOT AFR). Remember to leave your OFLA at 1.001 in the WOT range and leave the PE Enrichment table alone, as well, at 1.001 as these are WOT modifiers at all times.

FYI for clarification, of course there are more fueling tables that can affect WOT fueling other than the 3 tables I mentioned above, such as adder tables like the IAT and ECT fuel adder tables, but adder tables are global, affect all fuel tuning open or closed loop. The tables I mentioned are direct WOT/PE parameters. Also, the way I tune WOT by leaving PE Enrichment table and OFLA tables alone at a value of 1.001 simplifies WOT tuning but you can surely adjust the others, just will complicate your tuning control.

Oh yah, dont pay attention to my '# of posts', something happened to my forum user acct, wiped out my posting counts, admin looking into it. this is to say Im really not a newby tuner! heehe

[5_Liter_Eater]

First thing is to make sure your injector values are as correct as possible. Then disable closed loop, COT, DFCO, CFCO. Then set your OLFA to 1 and flatline your PE to whatever you want to command at WOT (13:1=1.131) and set the PE enable to stockish; don't disable PE or delay it's onset. Clear out any residual fuel trims and you're ready to tune with. If you're short on time I'd recommend skipping the VE tuning alltogether because it's rarely referred to under 4000 RPM and the MAF solely determines airflow over 4000 RPM, but if you want to do it then disable the MAF and start logging with a histo that plots the AFR error against the VE table. With WB tuning you don't need to worry about not entering PE. AFR error is AFR error so if you command a different AFR through PE it doesn't matter, it's how far off from that commanded you are that matters. Just keep an eye out for KR and excessively lean AFR whether you're in PE or not. Remember in open loop the PCM does not correct for any AFR error; thats the point. Copy and paste the error numbers into your VE (multiply by %) and if you have a secondary VE table copy the appropriate rows into it. Re-enable the MAF and plot the AFR error against the MAF table. Realize that any work you did on the VE table is moot when MAF tuning. Dont be surprised if you are within +-5% on the VE and your first MAF log is now +-15%. MAF and VE are two independent airflow metering/calculating methods.

Questions/comments?

[SSUte01]

FYI for clarification, of course there are more fueling tables that can affect WOT fueling other than the 3 tables I mentioned above, such as adder tables like the IAT and ECT fuel adder tables, but adder tables are global, affect all fuel tuning open or closed loop. The tables I mentioned are direct WOT/PE parameters. Also, the way I tune WOT by leaving PE Enrichment table and OFLA tables alone at a value of 1.001 simplifies WOT tuning but you can surely adjust the others, just will complicate your tuning control.

Normally I would be inclined just to read and leave it to a matter of opinion and a 'matter of horses for courses' but some of the advice above although allowing you to reach the means is a poor example for the OP trying to learn, IMO, I'm not having a go but there are easier and better ways of tuning in this context. Setting your commanded AFR under PE conditions to Stoich/Eq ratio ie 14.68ish/1.001 = 14.61 and then raping your airflow model to achieve deisred AFR of ~12.8:1 based on 'eyeballing' when you have the tools to do it properly and far more accurately is not the 'best' way of tuning for these vehicles.

Put simply what generally we are trying to do is create an accurate airmass model of our respective cars and from that model the PCM can accurately calculate the precise amount of fuel delivered ie PW to achieve the desired AFR.

The MAF curve is an airmass model and the VE (along with the bias calcs etc) is another airmass model, now if you are running SD you need not worry about the MAF. I reiterate, the VE table despite what everyone seemingly keeps saying is not a fueling table, yes fuelling is derived directly from it but it is not a fueling table.

How to make an accurate airmass model (and therefore fueling)

Set your commanded AFR to what you want it to be once you are finished tuning the vehicle, so OLFA is set where you want it for cold start, hot start and I recommend 1.0 at operating temps (although some big cams dont like stoich at some loads but that is off topic) and set your PE exactly as you want it ie approximately 1.14 (~12.8) from 2000rpm up, I personally like it slightly fatter above 6000rpm and then once you have finished your airmass model you can use a dyno or strip (much harder) to find the optimum AFR for your setup.

Set all your adders etc where you want them including spark and so on, tune the car how it will be in the long run, there are some personal exclusions on that when I tune but essentially I tune it how it will be driven once it is gone.

Now assuming your wideband, narrowband (not really suitable), EGT etc or whatever system you are using is accurate, and we have to or you are forever dealing with variables and no fixed point. Anyways, most common method is to use a wideband to create an accurate airmass model

- Disable DFCO/CFCO as this will skew all decel data, just use temp setting to max
- Set OLFA as you intend to leave it
- Disable COT
- Set spark as you wish to start, tuning spark and airmass modeling is a interleaved process, you can copy high to low if you wish, eliminating another variable
- Set PE to where you want it ~1.14 or so
- Turn off Lean Cruise of you have it
- Disable Closed Loop, pulling out the narrowband to install the wideband does this for you
- Reset the LTFTs (I personally disable them permanently regardless but that is off topic also)

Now using AFR Error against VE or MAF your aim is to get this to zero reagardless of the commanded AFR. Once you are within 2% or so go for Mult % - Half and experience will tell you if there is any skewed data in there. Get a good sample amount and do your best to achieve steady state in each and every cell.

I like to do tune by area, WOT, Cruise and Idle but if you wish you can combine them, this is personal choice.

Ok, so now you have an accurate air model for your vehicle, if you change spark you will have verify that this hasn't changed the model, hence an interleaved process.

The advantage of this is when you change the commanded AFR, say you up the PE to 1.20 (12.2) , the end result 'should' be an AFR of 12.2 without any further tuning, this is where you can use a dyno etc to optimise AFR for power. If your VE and/or MAF is accurate then you can change the commanded AFR with confidence that your actual AFR = commanded AFR not some sort of compromised result.

*This is somewhat controversial but I always (on setups that will utilise CL) re enable CL and then repeat the process for cruise (and idle to some extent) using STFTs against VE and/or MAF as despite what most say on the majority of setups serviceable NB sensors are very accurate at stoich and only stoich, I stress in most cases. This is a personal choice and for me just adds an independent means of verifying what the wideband has measured, I usually find it is within ~2%. I dont bother with this on idle on cammed setups as IMO NBs are not accurate on the vast majority of mild cams and up, there are exceptions but this is the rule for me.

Once this is done

- Re-enable Closed Loop, Lean Cruise (I disable it as most common widebands struggle with leaner AFRs I rather use closer to stoich and then command as apt), DFCO as appropriate.
- Turn COT back on (if desired)

You now should have a well modeled VE setup. Now it is a matter of optimising spark and re-checking the VE. If you are using a MAF I will now repeat the WB/NB process against the MAF curve.

There are a million ways to skin a cat and there is a little more to it than that but in essence and sticking to basics that is my opinion and tuning methodology for these cars. Once you start talking aftermarket injectors, power adders, larger cams etc there are other things to consider but again that is the basics.

I would do all of this before worrying to much about areas such as cold start, RAF etc as especially RAF is heavily dependent on what the PCM thinks is actual AFR so before you end up chasing your tail on idle at least get the fueling right, the spark at least close then work on the others. You can do this prior to cruise and WOT if you wish.

I sincerely dont wish to offend anyone and hope this is of some help to the OP.

[5_Liter_Eater]

Well said.

[Cantalope Kid]

This is sticky worthy...

[Gh0st]

This is sticky worthy...

Not really, the information is every where as it is. The problem is sifting through the bullshit