HOW TO: Setting up Fuel Trim Graph in VCM Scanner V3 on Virtual VE Vehicles

[99LS1SS]

Does DoD need to be disabled when tuning VVE?

[schpenxel]

There's a VVE table for DOD enabled and one for DOD disabled. Most people just disable it and only really tune the DOD disabled one but you could do both if you wanted

[mevershed]

Can someone help me get my tune better.
I have the ve vs fuel trims in the log. if I need to change or add to the log set please let me know what needs to be added.
Not sure how to transfer the fuel trims in the chart to the VVE chart.

I also include MAF Hz vs LTFT-STFT how do I adjust that in my airflow graph of tune, Just remove or add the fuel trim number in each block from the number in the airflow graph?

Thanks
MIke

[8850]

Here's a good link how to set up your scanner.

https://www.hptuners.com/forum/showt...621#post416621

From there open your file. Change the drop down box on the left to manifold switch to open. The default table is Closed. Open the log file. Click VE vs. Fuel Trims. Highlight and copy the graph. Go back to your file to the VVE editor table, highlight and right click paste special, then click multiply by %. You want to get all the cells you can but you can manually change some cells if there are ones you didn't get much data. If your log represents the way your normally drive then you should have most of the cells corrected. Finally click "calculate coefficients" over on the left. It will update the table and you are done after saving the file. You should see some values in the table change when you click calculate coefficients.

I think you will need more frames logged than this log has.

[mevershed]

Thank you that helps.
Just takes driving in a bunch of different situations while logging?
I guess this is where a dyno is a needed tool

[schpenxel]

Yeah, I also like to manually go in and look at the 3D graph view and adjust spots that weren't picked up in a log. You should be able to spot trends and apply them to other cells to at least get you more in the ballpark. And I usually use the smooth feature as well

[roastin300]

Hey schpenxel: If you perform those MAF Failing tasks but forget to go into Engine-->Airflow-->Dynamic and max out the High RPM Disable and Re-enable, will you still be reading the MAF?

I was getting 1 of those 3 codes, so I assume the MAF was failed as you state. However, the VE table is very choppy and seems to have poor repeatability. Thanks for your feedback.

[02Ls1]

Guys I just finish setting up my scanner to tune my VVE, I got a couple of questions.

Can I tune the VVE with the MAF on stock settings? I tune my MAF using the MAF fuel trim graph from schpenxel work great my fuel trims are on point.

Going boosted it there's a way running just on VVE? Like the older models that they can go on SD on a 2/3 bar VE table?

Now since my fuel trims are good with just the MAF fuel trim graph what will the VVE fix or do getting it tune? I'm new to the VVE tables sorry if I sound crazy. I do have a small issue with my cammed g8, when I take off I feel like a it fall on he's face like for like a second and then reacts. They say tuning the VVE would get it done.

[5FDP]

Disable the MAF like you would on a GEN 3.

Should be able to set the fail high to 2hz and the low fail to 1hz, set the DTC's to MIL on first error. Log MAF status to make sure it's failed and then you know it's running off the VVE.

[02Ls1]

I was looking at a video and say the same, So tuning the VVE correctly i can just leave it running on VVE? No MAF?

Now I should disable the LTFT so it wont mess with my fuel right? and leave it on closed loop?

[mowton]

I was looking at a video and say the same, So tuning the VVE correctly i can just leave it running on VVE? No MAF?

Now I should disable the LTFT so it wont mess with my fuel right? and leave it on closed loop?

My preference is open loop so there are no trims messing with the fueling....you get what you asked for If you must tune in closed loop then I always recommend leaving the LTFT enabled becasue it collects most of the error in a particular zone so the STFT is only moving enough to fine tune the fueling requirement ...more stable to me. Disabling the LTFT makes the STFT have to do all the trimming and if you are far off, it will be swing quite a bit as you go through your tuning progressions.

Ed M

[8850]

My preference is open loop so there are no trims messing with the fueling....you get what you asked for If you must tune in closed loop then I always recommend leaving the LTFT enabled becasue it collects most of the error in a particular zone so the STFT is only moving enough to fine tune the fueling requirement ...more stable to me. Disabling the LTFT makes the STFT have to do all the trimming and if you are far off, it will be swing quite a bit as you go through your tuning progressions.

Ed M

Correct me if I'm wrong but I always thought when in closed loop you we reading off the VVE table below about 4K rpm when not in PE. In OL doesn't the Mass air meter then read for these part throttle readings? If you tune in OL and with wideband connected then you aren't logging to tune the VVE table but instead the mass air frequency table.

To tune LTFTs in OL you need a wideband. In CL no wideband needed when not in PE?

[mowton]

Correct me if I'm wrong but I always thought when in closed loop you we reading off the VVE table below about 4K rpm when not in PE. In OL doesn't the Mass air meter then read for these part throttle readings? If you tune in OL and with wideband connected then you aren't logging to tune the VVE table but instead the mass air frequency table.

To tune LTFTs in OL you need a wideband. In CL no wideband needed when not in PE?

Open Loop merly says that the narrowband O2 sensors will not be used to control fueling so the LT/STFT will be inactive and are not being tuned...the MAF or VE/VVE values are being tuned based on the WB reproted error.

Closed Loop says the LT/STFT's will be used so the AFR is constantly being corrected to maintain the Stoich value. When you go into WOT or Power Enrichment, the PCM enters Open Loop no matter what mode its set to and will reset the trims to zero. One note is if the trims are positive entering WOT/PE, then the PCM will also add that amount of fuel to the PE enrichment value.

MAF Airflow Sensor is used to report the amount of air being ingested by the engine and eventually is used to calculate the g/cyl (Cylinder airmass) which is then used to calculate the amount of fuel needed to satisfy the commanded AFR.

VE/VVE is another airmodel used by the PCM which is developed from a fixed table (VE) or a set of coeeficients that feed an algorithm (VVE) and can be used to develp the Cylinder AIrmass as well.

The GM system actually uses both (blended/Hybrid mode) where the MAF reports the airflow and the VE/VVE is used to validate the MAF value and during transients, is used to "adjust" the MAF value to compensate for the dynamic effects of airflow in the intake manifold....Hard accel leads to the need to fill the vacuum in the intake and hard decels result in the intake have a reserve of already reported airmass.

When we tune MAF only, we set the High RPM Disable to a value lower than the stock 4000 rpm like 400. This 4000 rpm threshold tells the PCM to use the blended mode we defined above until then, and when it is exceeded, use only the MAF. That is why we oush the disable down below to 400 to operate in MAF only so we can tune the MAF table with the LT/STFT (Closed Loop) or the WB error (Open Loop)

When we want to tune the VE/VVE, we need to fail the MAF so the PCM reverts only to the VE/VVE airmodel for fueling...or what we otherwise call Speed Density. This we do by defining P0101-103 as fail on first error and set the High MAF Freq fail to a artificially low value (1 HZ) to force a MAF fial in the PCM.

Hope this helps..

Ed M

[8850]

Thanks Ed! To sum up what you have said to tune MAF and VVE. (I?ve also attached a configuration to tune both)

To tune the MAF for correct afr with your wideband you first convert to OL with High RPM disable set to 400+/- rpm. Then adjust your MAF frequency table which will be based on Cylinder Airmass and MAF hz values.

To adjust VVE and trims, same configuration wideband isn't needed, set back to CL, adjust your High RPM disable back to 4000 rpm and set PO101-103 and MAF frequency as you noted above. And best to set LTFTs so you are always slightly negative so afr is not leaned when going into PE.

[mowton]

Thanks Ed! To sum up what you have said to tune MAF and VVE. (I?ve also attached a configuration to tune both)

To tune the MAF for correct afr with your wideband you first convert to OL with High RPM disable set to 400+/- rpm. Then adjust your MAF frequency table which will be based on wideband error values collected in accordance with the MAF HZ axis values. Create a Graph that matches your Tunes MAF table axis values and the parameter will be the WB Error parameter

To adjust VVE same configuration the same wideband is needed, maintain OL, adjust your High RPM disable back to 8000 rpm and set PO101-103 and MAF frequency high fail as you noted above. Create a Graph that matches your tunes VE/VVE table axis values and the parameter will be the WB Error parameter.

Corrected...

Ed M

[Jay@HAP]

I have an easy question and have spent most of the afternoon searching for it but haven't found it.

When you make a change to the VVE table, using the histo or manually changing it, do you?
hit the calculate coefficient button then go to the other VE tables and make the same changes OR copy paste the first VE table to the others. If so, do you hit the calculate coefficient button each time?

Thanks for any help.

[GHuggins]

You have to hit calculate coefficient before it'll let you go to any of the other tables, so make changes - smooth or whatever you prefer - calculate coefficients - copy the table that is now present - go to next table - past - calculate - next table - paste - calculate - and on and on

Otherwise you'll lose all of the changes you've made - which sucks :/

[Jay@HAP]

You have to hit calculate coefficient before it'll let you go to any of the other tables, so make changes - smooth or whatever you prefer - calculate coefficients - copy the table that is now present - go to next table - past - calculate - next table - paste - calculate - and on and on

Otherwise you'll lose all of the changes you've made - which sucks :/

Thank you for reply. That's how I've been trying to do it.

This thing has been a pain in the ass.

This is the first E38 I've done that suffers from the rich after hot flash. It won't idle after any VVE changes. Shit shouldn't be this hard. lol

[metalbew]

Can i ask why you started on VVE graph and close to the bottom you are on VE vs Fuel Trims then close to the bottom you are at LTFT + STFT, then at the end you are back to the VVE vs Fuel Trims and all that other stuff disappeared?

[5FDP]

He had just changed the label on the graph is all. You could either have it say VE vs Fuel trims or LTFT + STFT. If you notice in the pictures the same parameters and math function is used.

My guess is that he did this write over a length of time or from two different scanner setups that used different labels. In the end you are still setting it up the same way.