RADustin
June 21st, 2022, 01:30 AM
Gents,
Using COS 05230001 on a built N/A 496 big block. It's speed density only, no MAF. Big AFR heads, 10:1 compression and a single plane port injection manifold. Just completed power tour with the truck and it did OK. Really didn't have much time to tune things in before we left, so I roughed it and left it OL and sent it. Now is the time to really get things dialed, honestly most hot rod swap people would probably call it good where its at- but I'm a bit particular.
We found a fuel tank vent issue, so my VE is off due to varied base fuel pressure over a log session. I'm going to basically start fresh and work my way back through the entire tune file. One major sticking point has always been excessive des. airflow and startup/friction airflow. Also warmed up(hot) idle AFR is spot on with current VE settings, but all 'cold' AFRs are SUPER rich. as an act of desperation I went in the OLFA (B3605) and took out 40-50% of fuel during warm up {insane but worked}. While warming up, the commanded vs actual EQ is FAR off but the end result works. Not ideal and I think it is throwing RAFPN calcs off and basically any airflow calc that is done before the engine is hot.
In an attempt to fix desired airflow to more sane numbers as well as maybe some of the startup and friction airflow tables, I'd like to better understand the VE correction factors. I also think this could help with my wildly rich warm up and help get airflows more accurate during warm up, which will make desired airflow more accurate from a better RAFPN. With the warm up so incredibly rich (and a commanded EQ of 1), it is impossible my RAFPN logging is accurate below operating temp. These ve correction factors are temp biased and initialize at a set baro reading apparently? I don't think EFI has this mapped but I was able to bring in the tables via a .cax.
I understand they are used to better match SD airflow calcs to MAF calcs, but if no MAF is present then the VE is the bible and therefore doesn't have a basis for a correction. So I half wonder if all the corrections should be set to 1 for a SD tune and the min and max correction limiters set to 0.999 and 1.001. Thoughts?
Basically my questions are how do these factors play into the final airflow calculations when we are running 100% speed density on the COS? How is the correction updated to correct VE to MAF if there is no MAF? Are we chasing our tails while VE tuning everytime we startup and log at different coolant temps since we potentially initialize a different ve correction (assuming it never gets updated during a run cycle)?
With all that said, how can I use my wideband to temperature correct my VE during warm up? Is VE corrections not what I'm looking for(although a potential issue) and I should be looking at remodeling the charge temp blending calcs? How do I get cold airflow actual to better match the PCM calcs? Obviously I can't change VE as once it is warm it is good. I can(and have) log a BEN for warm up. This is how I 'tuned' the B3605 table. What I would prefer to do is to find a way to get the calc airflows to match actual while warming up, and then use the OLFA B3605 to set it slightly rich so the engine is happy. Setting a target lambda of 1.5 to actually get .9 or so seems very wrong.
I know I'm all over the place here but just looking for a general conversation from both the EFI crew on how their COS is programmed and from users on what has worked for them.
Thanks!
Using COS 05230001 on a built N/A 496 big block. It's speed density only, no MAF. Big AFR heads, 10:1 compression and a single plane port injection manifold. Just completed power tour with the truck and it did OK. Really didn't have much time to tune things in before we left, so I roughed it and left it OL and sent it. Now is the time to really get things dialed, honestly most hot rod swap people would probably call it good where its at- but I'm a bit particular.
We found a fuel tank vent issue, so my VE is off due to varied base fuel pressure over a log session. I'm going to basically start fresh and work my way back through the entire tune file. One major sticking point has always been excessive des. airflow and startup/friction airflow. Also warmed up(hot) idle AFR is spot on with current VE settings, but all 'cold' AFRs are SUPER rich. as an act of desperation I went in the OLFA (B3605) and took out 40-50% of fuel during warm up {insane but worked}. While warming up, the commanded vs actual EQ is FAR off but the end result works. Not ideal and I think it is throwing RAFPN calcs off and basically any airflow calc that is done before the engine is hot.
In an attempt to fix desired airflow to more sane numbers as well as maybe some of the startup and friction airflow tables, I'd like to better understand the VE correction factors. I also think this could help with my wildly rich warm up and help get airflows more accurate during warm up, which will make desired airflow more accurate from a better RAFPN. With the warm up so incredibly rich (and a commanded EQ of 1), it is impossible my RAFPN logging is accurate below operating temp. These ve correction factors are temp biased and initialize at a set baro reading apparently? I don't think EFI has this mapped but I was able to bring in the tables via a .cax.
I understand they are used to better match SD airflow calcs to MAF calcs, but if no MAF is present then the VE is the bible and therefore doesn't have a basis for a correction. So I half wonder if all the corrections should be set to 1 for a SD tune and the min and max correction limiters set to 0.999 and 1.001. Thoughts?
Basically my questions are how do these factors play into the final airflow calculations when we are running 100% speed density on the COS? How is the correction updated to correct VE to MAF if there is no MAF? Are we chasing our tails while VE tuning everytime we startup and log at different coolant temps since we potentially initialize a different ve correction (assuming it never gets updated during a run cycle)?
With all that said, how can I use my wideband to temperature correct my VE during warm up? Is VE corrections not what I'm looking for(although a potential issue) and I should be looking at remodeling the charge temp blending calcs? How do I get cold airflow actual to better match the PCM calcs? Obviously I can't change VE as once it is warm it is good. I can(and have) log a BEN for warm up. This is how I 'tuned' the B3605 table. What I would prefer to do is to find a way to get the calc airflows to match actual while warming up, and then use the OLFA B3605 to set it slightly rich so the engine is happy. Setting a target lambda of 1.5 to actually get .9 or so seems very wrong.
I know I'm all over the place here but just looking for a general conversation from both the EFI crew on how their COS is programmed and from users on what has worked for them.
Thanks!