Can't affect VVE?

[cscott]

I'm attempting to tune SD via VVE in my C6Z, but I can't seem to affect the fueling with even large changes to VVE. I've had no issue tuning MAF though. My tune (attached), has the MAF disabled. No matter what changes I make to the VVE (calculating coefficients too), there is no change in the fueling. The car was moderately modified, including third-party tune, when I bought it. Cam, LT, injectors... and now heads. I suspect there is some property in the cars tune that I can't find which is preventing me from affecting fueling via VVE.

Can anyone take a look in the tune, and let me know if there is anything set that would prevent changes to VVE from changing fueling? There seems to be something else in control of the fueling w/ the MAF disabled.

TIA

[JayRolla]

There are 4 different VVE tables. 1 usually used. I always make same changes to all of them. Are you doing this?

[cscott]

I made the changes to the 2 non-DoD tables since the car isn't DoD. Should I be updating all 4 tables?

[JayRolla]

I made the changes to the 2 non-DoD tables since the car isn't DoD. Should I be updating all 4 tables?

I always do even if I know it's dod or not but that might not be your issue.

[07GTS]

not sure if its failing properly try this

[edcmat-l1]

Need to check your codes when you get it running and make sure P0103 is set. If it isn't, you're not in speed density and no changes you make will have any effect.

[Alvin]

There are 4 different VVE tables. 1 usually used. I always make same changes to all of them. Are you doing this?

only the last table in that list is used..

There is a pid you can logged "MAF status" or something alone those lines. Make sure it says MAF failed. Make changes to the last table in that list (OPEN) and you should be good to go.

[STAGEUP]

only the last table in that list is used..

There is a pid you can logged "MAF status" or something alone those lines. Make sure it says MAF failed. Make changes to the last table in that list (OPEN) and you should be good to go.

This....

[cscott]

I still seem to be chasing my tail.

Latest attempt:

1. Created a scan "1". Scan includes a pid verifying MAF failed (disabled) and some AFR data in the AFR_Error_13.5 histogram. I created this histogram because something is still generating a value for Air-Fuel ratio commanded which values seem erratic. I the erratic values made it too difficult to compare changes, so I I created the AFR_Error_13.5 histogram with a fixed 13.5 as target value.

2. Select all cells in the last VVE table (Manfiold Switch Open).

3. Multipled all cells by .8

4. Calculated coefficients
,
5. Flashed to ECM

6. Generated scan "2". As can be seen in the AFR_Error_13.5 histogram, there was no substantial affect.

[edcmat-l1]

30 seconds of run time is not near long enough to make a consensus. Engine isn't up to operating temp.

Put it back in closed loop and use the fuel trims to dial it in. Run it for MUCH longer after making any changes. You can't flash it and judge the results of your changes in the first 30 seconds of run time. You shouldn't even be paying attention to what the AFR is at that point.

[Alvin]

I still seem to be chasing my tail.

Latest attempt:

1. Created a scan "1". Scan includes a pid verifying MAF failed (disabled) and some AFR data in the AFR_Error_13.5 histogram. I created this histogram because something is still generating a value for Air-Fuel ratio commanded which values seem erratic. I the erratic values made it too difficult to compare changes, so I I created the AFR_Error_13.5 histogram with a fixed 13.5 as target value.

2. Select all cells in the last VVE table (Manfiold Switch Open).

3. Multipled all cells by .8

4. Calculated coefficients
,
5. Flashed to ECM

6. Generated scan "2". As can be seen in the AFR_Error_13.5 histogram, there was no substantial affect.

I recommend at least 15 minutes of data of DRIVING to work with. Snapshots don't work.

Also these have a injector tip temperature offset table that maxes out after a reflash. It takes about 15 minutes for that to resolve. It will cause it to be overly rich especially in low load areas. You can zero it out to avoid this. Almost no GM trucks come with this table populated. I've never had any issues zeroing it out. No aftermarket injector I'm aware of comes with data for this table.

[JayRolla]

only the last table in that list is used..

There is a pid you can logged "MAF status" or something alone those lines. Make sure it says MAF failed. Make changes to the last table in that list (OPEN) and you should be good to go.

Thats why I said only one is used. I am just a weirdo and make them all match.

To OP like edcmat said you're not even at proper engine temp. Should not even start logging till you're at normal temp. Then you need to drive it for some time and use the fuel trims to make your changes. Should be in closed loop using the narrowbands to adjust your VE table and MAF curve for cruising, idle, closed loop.

[cscott]

The car was almost completely un-drivable. Bucking/sputtering, etc. AFR showed super-rich, so I came home to start working with it. I was hoping to lean it out enough to be able to drive it. Can I assume that the 20% reduction in the VVE will have an affect after driving for a short distance so I can safely continue on a longer test drive?

The short scans were just meant as a test to determine if I was able to make a change so I'd have some level of confidence before I went for another test drive.

FWIW, the tune that came with car appears to be MAF only. Dynamic Airflow High RPM Disable/Enable were set to 400 rpm / 390 rpm.

[cscott]

I recommend at least 15 minutes of data of DRIVING to work with. Snapshots don't work.

Also these have a injector tip temperature offset table that maxes out after a reflash. It takes about 15 minutes for that to resolve. It will cause it to be overly rich especially in low load areas. You can zero it out to avoid this. Almost no GM trucks come with this table populated. I've never had any issues zeroing it out. No aftermarket injector I'm aware of comes with data for this table.

Seems related to what I was experiencing. I'll check it out. Thanks.

[cscott]

Thats why I said only one is used. I am just a weirdo and make them all match.

To OP like edcmat said you're not even at proper engine temp. Should not even start logging till you're at normal temp. Then you need to drive it for some time and use the fuel trims to make your changes. Should be in closed loop using the narrowbands to adjust your VE table and MAF curve for cruising, idle, closed loop.

So I shouldn't bother with WB until testing WOT/PE? I see now why the tune you provided earlier had Dynamic Airflow High RPM Disable/Enable set so high. So the idea is to use the narrow bands to gather fuel trim data... but by setting Dynamic airflow enable high, the ECM won't actually use it until Dynamic Airflow reinstated?

[edcmat-l1]

So I shouldn't bother with WB until testing WOT/PE? I see now why the tune you provided earlier had Dynamic Airflow High RPM Disable/Enable set so high. So the idea is to use the narrow bands to gather fuel trim data... but by setting Dynamic airflow enable high, the ECM won't actually use it until Dynamic Airflow reinstated?

Closed loop has nothing to do with airflow. Dynamic airflow determines when the PCM is operating in "Hybrid" mode or "MAF only". Has nothing to do with closed loop.