Questions/issues with vve tuning c7 zo6

[Greg Powrie]

I am newer to hp tuners and having a problem trying to tune the vve on my 2016 zo6. First issue is when I setup the scanner histogram for pressure ratio it doesn't seem to read correctly. I am logging barometric pressure sae, intake manifold absolute pressure sae, and manifold absolute pressure- hi-res. Other issue is when I failed the maf and start the car the timing retards negative and the car obviously runs terrible. I have the car running well in maf only mode. If maf only the timing at idle is 13-23 degress, maf failed between -7 and about 5 degrees. Don't understand where the change in timing numbers is coming from. I can post the log files and tune file in a few if needed. Also the car has a camshaft, DOD delete, upper and lower blower pulleys, headers, intake, ect.

[Higgs Boson]

delete intake map sae and leave hi-res in Channel list. make sure your using Pressure Ratio in your Graph.

the ecm is torque based and without the maf you will need to more carefully modify your torque tables (Virtual Torque under the Edit menu)

first get your VVE tuned correctly and some of that spark retard will go away as it is.

[Greg Powrie]

Thanks for the response. I delete intake map sae from the channel list. I am using pressure ratio under engine-airflow-volumetric efficiency. I have been working on the torque table a bit. I have noticed that it seems that everything seems to affect the torque model. I thought at this point it would make more since to tune the vve before going too on the torque tables. I bought the tuning school books for the gen 5. They get the car running but its less than perfect. They don't explain what any of the changes are doing really just what to change and how much.


Also I just went back through the logs with the failed MAF and noticed the cylinder airmass changed significantly at idle.
it was idling at .58 where its normally around .27 in MAF only. I didn't change that area of the timing table as it never touched it until failing the maf. I think I can alter that area of the timing table and get the car to run so that I can work on the vve. I don't see why the airmass should have gone up or changed significantly failing the maf.

[TriPinTaZ]

Thanks for the response. I delete intake map sae from the channel list. I am using pressure ratio under engine-airflow-volumetric efficiency. I have been working on the torque table a bit. I have noticed that it seems that everything seems to affect the torque model. I thought at this point it would make more since to tune the vve before going too on the torque tables. I bought the tuning school books for the gen 5. They get the car running but its less than perfect. They don't explain what any of the changes are doing really just what to change and how much.


Also I just went back through the logs with the failed MAF and noticed the cylinder airmass changed significantly at idle.
it was idling at .58 where its normally around .27 in MAF only. I didn't change that area of the timing table as it never touched it until failing the maf. I think I can alter that area of the timing table and get the car to run so that I can work on the vve. I don't see why the airmass should have gone up or changed significantly failing the maf.

It is common for a larger camshaft to have an increased MAP value or "pressure Ratio". This is because the larger cam has more overlap and reduces the amount of vacuum in the intake manifold therefore raising the pressure ratio which is directly derived from MAP. 100KPA = 1 atmosphere or zero vacuum. When a car is at idle with the throttle blade closed the intake manifold actually has negative pressure (IE less them 100KPA or 1.0 Pressure ratio).

The solution is if your car now idles at .58 pressure ratio, you need to move the timing values from the .27 area down into the .58 area. Then blend the timing into the rest of the higher RPM values just above idle.

You're likely going to need to adjust your Virtual Torque as well. Also you likely will need to reduce the VVE values in the pressure ratio areas where your new idle sits.

[Higgs Boson]

the spark table is against airmass, not map. you don't move your timing value.

[Greg Powrie]

Made a lot of progress last night with it. The reason the air mass went up was the amount of timing it was pulling due to the torque model. Played with the virtual torque and didn't get anywhere. Went back to where I started with the torque tables and started making the adjustments to the vve. That changed the commanded axle torque significantly which the torque table was not unless I made a huge adjustment to it. Now the car idles and low load is looking good. The vve table needed a lot of adjustment to get in the ball park. It was getting late so I was kinda doing a hack job of it and not smoothing it much. Need to clean it up and can now see kinda where it's going. I am hoping that this explains some of the issues I was having with the torque model in maf only. Every adjustment I made to the torque table it seemed would only give me about 1/4 of the affect I expected. I only have 1 spot that is limiting me in maf only so I hope this ends up helping that. Right now it limits me in first at the track. Traction control off it would ramp the throttle from 40% to wot all the way through first gear. Log shows the source being trans during that though so I may have to look elsewhere, not sure on that 1 yet.

[Greg Powrie]

Also getting the vve in line brought the pressure ratio back to .27-.28 at idle. The timing g being pulled is what raised it to .58

[TriPinTaZ]

the spark table is against airmass, not map. you don't move your timing value.

You're right, but he was referring to pressure ratio and I didn't think it through and assumed he was referring to spark vs pressure ratio. Which as you mentioned doesn't exist lol.

[Greg Powrie]

You're right, but he was referring to pressure ratio and I didn't think it through and assumed he was referring to spark vs pressure ratio. Which as you mentioned doesn't exist lol.

Sorry I think faster than I type and I ment the air mass came back down not the pressure ratio. I am not used to talking pressure ratio and air mass. Everything I am used to is kpa vs rpm so this is a little different. Lol.