VE table tuning vs horsepower ???
Thread Starter
Joined: May 2003
Posts: 377
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From: Fairfax County, VA (You know you're here when you see the bad roads)
VE table tuning vs horsepower ??? Correct me if Im wrong, but the VE table is the computers attempt to map out how much air gets in to the cylinder and any given load vs rpm spot on the map.
So, is it reasonable to assume that when tuning for mods, a good indication as to the mods effectiveness would be it impact on the ve table?
i.e., should I expect that when I add headers, intake, etc...much of the ve table should increment up in value, indicating that MORE air is getting in to the cylinder due to the modifications?
Here is the puzzling thing, after tuning for all on my mods (headers, intake, etc.) my entire VE table has all of the values settling LOWER that my stock VE table. On the order of 10% lower. Am I missing something??? Shouldnt my VE tuning trend towards a HIGHER volumetric efficiency??
FWIW, I have my commanded VE afr set to 14.7 stoich, and my PE commanded set to around 12.8 or so. The above trend is noticed when VE tuning using the redily available methods to disable, MAF, adaptive fueling, etc.
THANKS!!!!
So, is it reasonable to assume that when tuning for mods, a good indication as to the mods effectiveness would be it impact on the ve table?
i.e., should I expect that when I add headers, intake, etc...much of the ve table should increment up in value, indicating that MORE air is getting in to the cylinder due to the modifications?
Here is the puzzling thing, after tuning for all on my mods (headers, intake, etc.) my entire VE table has all of the values settling LOWER that my stock VE table. On the order of 10% lower. Am I missing something??? Shouldnt my VE tuning trend towards a HIGHER volumetric efficiency??
FWIW, I have my commanded VE afr set to 14.7 stoich, and my PE commanded set to around 12.8 or so. The above trend is noticed when VE tuning using the redily available methods to disable, MAF, adaptive fueling, etc.
THANKS!!!!
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Some thoughts:
- was the previous tune correct (matching the previous engine mods)...?
- is the wideband working correctly...?
- do all the injector tables match the actual injectors...?
- did you set the stoich AFR in the tune to the correct value for the fuel you're using.
Are you comparing the modified VE against your previous one or against stock...?
- was the previous tune correct (matching the previous engine mods)...?
- is the wideband working correctly...?
- do all the injector tables match the actual injectors...?
- did you set the stoich AFR in the tune to the correct value for the fuel you're using.
Are you comparing the modified VE against your previous one or against stock...?
Thread Starter
Joined: May 2003
Posts: 377
Likes: 0
From: Fairfax County, VA (You know you're here when you see the bad roads)
Some thoughts:
- was the previous tune correct (matching the previous engine mods)...?
- is the wideband working correctly...?
- do all the injector tables match the actual injectors...?
- did you set the stoich AFR in the tune to the correct value for the fuel you're using.
Are you comparing the modified VE against your previous one or against stock...?
- was the previous tune correct (matching the previous engine mods)...?
- is the wideband working correctly...?
- do all the injector tables match the actual injectors...?
- did you set the stoich AFR in the tune to the correct value for the fuel you're using.
Are you comparing the modified VE against your previous one or against stock...?
-Im not sure I can completely rule out that my wideband may be doing something wierd, but as far as I know it is functioning properly, and calibrates as it should in free air.
-the injectors are stock
-the stoich value is unchanged from factory. Im tuning a stock ls1 with bolt ons to run pump gas
relevant mods are long tubes, lid, removed AIR injection. No obvious leaks
Correct me if Im wrong, but the VE table is the computers attempt to map out how much air gets in to the cylinder and any given load vs rpm spot on the map.
So, is it reasonable to assume that when tuning for mods, a good indication as to the mods effectiveness would be it impact on the ve table?
i.e., should I expect that when I add headers, intake, etc...much of the ve table should increment up in value, indicating that MORE air is getting in to the cylinder due to the modifications?
Here is the puzzling thing, after tuning for all on my mods (headers, intake, etc.) my entire VE table has all of the values settling LOWER that my stock VE table. On the order of 10% lower. Am I missing something??? Shouldnt my VE tuning trend towards a HIGHER volumetric efficiency??
FWIW, I have my commanded VE afr set to 14.7 stoich, and my PE commanded set to around 12.8 or so. The above trend is noticed when VE tuning using the redily available methods to disable, MAF, adaptive fueling, etc.
THANKS!!!!
So, is it reasonable to assume that when tuning for mods, a good indication as to the mods effectiveness would be it impact on the ve table?
i.e., should I expect that when I add headers, intake, etc...much of the ve table should increment up in value, indicating that MORE air is getting in to the cylinder due to the modifications?
Here is the puzzling thing, after tuning for all on my mods (headers, intake, etc.) my entire VE table has all of the values settling LOWER that my stock VE table. On the order of 10% lower. Am I missing something??? Shouldnt my VE tuning trend towards a HIGHER volumetric efficiency??
FWIW, I have my commanded VE afr set to 14.7 stoich, and my PE commanded set to around 12.8 or so. The above trend is noticed when VE tuning using the redily available methods to disable, MAF, adaptive fueling, etc.
THANKS!!!!
Thread Starter
Joined: May 2003
Posts: 377
Likes: 0
From: Fairfax County, VA (You know you're here when you see the bad roads)
I agree, and what you said makes logical sense. But if that were the case, then wouldnt the expected outcome from the increased airflow be an adjustment upward in the VE table? Not down as I am seeing? The only other possibility if your statement is correct would be that by installing headers and an intake I have drastically DECREASED my engines power and efficiency. See what Im trying to say?
Thread Starter
Joined: May 2003
Posts: 377
Likes: 0
From: Fairfax County, VA (You know you're here when you see the bad roads)
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kind of odd since you didnt cam it......with aftermarket cams you will see that cause they arent as efficient at idle and cruise so you have to take some out. However the mid to top end you will probably have to add a bunch.
But it might be that with those headers that the volume effiency at idle isnt as good......and really gets better with RPMs so you have to add a bunch. If the wideband is comfirming that........I would tune it to what it is telling you. And check the plugs here and there also. They are the real tell tells of what is going on.
But it might be that with those headers that the volume effiency at idle isnt as good......and really gets better with RPMs so you have to add a bunch. If the wideband is comfirming that........I would tune it to what it is telling you. And check the plugs here and there also. They are the real tell tells of what is going on.
Thread Starter
Joined: May 2003
Posts: 377
Likes: 0
From: Fairfax County, VA (You know you're here when you see the bad roads)
yeah, id be very interested to see what the commanded AFR errors would be for VE when scanning a completely stock car with stock tune. I would assume that everything would be dead on for the most part....but maybe not. If not, that would prove your theory.
