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Thread: Tuning VVE and zone boundries

  1. #1

    Tuning VVE and zone boundries

    I'm working on a 2015 base corvette with an A&A supercharger system. The maf dialed in fine at wot and the car is making about 600 rwhp with nothing more than the kit at around 7.5 lbs of boost and an alky control system. However the car drove horribly at part throttle/light load and low rpm which I feel is the due to the 4" charge pipe and the location of the maf before and after a bend.

    So, I'm trying to tune the vve and I'm not having much luck. Up to this point, everything I've tuned with vve was done using the old 2.24 version of software with the bluecat tool and never had a problem. Now I'm using version 3 software for the first time and using the built in ve tool to dial things in and I'm not having any luck.

    It seems that we have a terrible lean spike when we cross the rpm zone 2-3. I've change the rpm setting for that zone and our lean spot moved with the rpm setting we changed.

    I know with the Bluecat tool it would change map and rpm zones automatically but this program doesn't. It would seem logical to change the map/baro ratio zones to something to fit our new map sensor but what reason is there behind tuning the rpm zones? I do have the baro sensor separate from the map sensor now also.

    I also just realized that changing the zone settings will change the entire look of the ve table itself? What am I missing in terms of the whole process of tuning the vve using this new program on a gen 5 engine/vehicle?

    I changed the rpm and map/baro scaling to fit our intended ranges.... I downloaded a tune file for a c7 z06 and noticed that even it does not go to a very high map/baro ratio, it only went to something like a 1.3. Why would that be the case and maybe even a more elementary question I have is why does the ve that is generated on a stock car always look so screwed up? All of the earlier stuff I have tuned with the bluecat tool I just put in the basic shape and values for the ve that I thought made sense and worked from that dialing in my afr error and everything always went smoothly. In order to dial this thing in using the fuel trims or the afr error from my wideband would lead to around a 25% increase in ve at the rpm zone 2-3 boundary.

    I have copied and pasted the generated ve from the intake manifold runner closed to the intake manifold runner open values also to make sure they are both the same.

    Any advice on what step I'm missing in this process or how and why the rpm zones would be adjusted would be much appreciated!

  2. #2
    Here is the current tune file....I'm sure the ve is a mess. We haven't attempted to go much over 4000 rpms and only part throttle so far. Just trying to figure out why the car has a lean stumble when it crosses 3200 rpms. Before when the 2-3 rpm boundary was set for 2500 rpms we got our stumble at 2500 rpms.
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  3. #3
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    Log?
    Post a log and tune if you want help

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  4. #4
    I changed my boundaries to match the break points on the vve table and I re-scaled the row and column axis to get better resolution to see if that may have anything to do with the issue....

    By moving the 2-3 boundary even higher in the rpm I've made the lean stumble mostly go away, but the afr is still going lean and the trims have to jump positive quite a bit to compensate.

    The ve table on this log is very smooth....yet for some reason its like it needs 10-15% more fuel immediately at the zone change no matter where I set the rpm for that zone.

    Attached is the updated tune file an a log to correspond.

  5. #5
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    I believe you're going to have to increase the 3500 RPM and up portions of the table quite a bit as it drops off pretty steep in the current curve. It will drop off at some point but I wouldn't expect it to drop off that steep or that early but I haven't tuned a log of gen 5's so who knows.

    It's going lean after 3500'ish RPM's which corresponds with the VVE table drop off

    Also I noticed it never went into PE in that log. I'd probably lower the throttle PE enable table a good bit for 3K+ RPM's

  6. #6
    Quote Originally Posted by schpenxel View Post
    I believe you're going to have to increase the 3500 RPM and up portions of the table quite a bit as it drops off pretty steep in the current curve. It will drop off at some point but I wouldn't expect it to drop off that steep or that early but I haven't tuned a log of gen 5's so who knows.

    It's going lean after 3500'ish RPM's which corresponds with the VVE table drop off

    Also I noticed it never went into PE in that log. I'd probably lower the throttle PE enable table a good bit for 3K+ RPM's

    Yeah, this log is on the dyno with a small amount of load applied. Map only was reading around 45 kpa at the point on the log I referenced so I'm not too worried about enrichment, but I wouldn't be a bad idea to enrich at that high of an rpm for sure.

    The ve table looks backward to me, but this table started out as the table generated from a z06 supercharged file. I'm not sure why the gmve numbers would be so high at a low rpm and fall off as rpms increase given the same amount of load unless it has something to do with the direct injections fuel pressure jacking up as rpm increases....but I also have meth injection which is going to replace a bunch of the fuel that should have been in the ve up in the corner of the map where its making boost and rpm so I didn't figure the shape of this table would be too horrible just to try.

    The thing this is, this lean spike will follow whatever value I input as the rpm break point for the 2-3 zone change. I've set it at 2500 rpms and it has the same lean stumble with the fuel trims jacking way up to compensate. If I move the 2-3 zone rpm it kinda screws up the ve table so I then paste back in the same ve table that had issues at 2500 rpms for example and now it passes by that rpm at the same pratio with no issues whatsoever, but when it gets to the new rpm for that zone change the stumble is there instead....

    Its like if i tune the ve based on afr error or what my trims are telling me its going to have a 15% jump immediately at whatever rpm my zone 2-3 is set for and that just doesn't seem right at all.

  7. #7
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    Yeah, that is strange. I'm hoping one of the guys that have worked with a log of gen 5 stuff will chime in with more first hand knowledge

  8. #8
    Senior Tuner Higgs Boson's Avatar
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    I haven't had a chance to look at your tune but do you have the Prediction Coefficients all zero'd out?

  9. #9
    A little log this time with a short burst of wide open throttle. i just wanted to see where the fuel was going to go....the coolant temp was kinda high so I didn't plan to make a full pull of it anyway. Under 3500 rpm the afr was pretty much right on target. At 3500 rpms it went super rich....

    We just called A&A and they said that our 4" tube must be a really early kit and that they have since added an air straightener to the 4" tubes, and then they went to a 3.5" tube with straightener. Ours is the 4" with straightener so it looks like we're going to get the 3.5" pipe and give that a shot back on the maf.
    Attached Files Attached Files

  10. #10
    Quote Originally Posted by Higgs Boson View Post
    I haven't had a chance to look at your tune but do you have the Prediction Coefficients all zero'd out?
    No. I didn't know that was necessary. Just zero all of those tables?

  11. #11
    Save your time chasing the straightner, its a little better but still sucks

  12. #12
    Quote Originally Posted by NTIMID8 View Post
    Save your time chasing the straightner, its a little better but still sucks
    I figure the smaller diameter pipe will do more for our issue than the straightener, but I'd still like to figure out the vve. Have you successfully tuned any gen 5 engine equipped vehicles in speed density? I'm sure people out there somewhere have to be tuning the vve in these things, we just haven't had many come through our shop but they are starting to show up now.

    I tuned a 2014 when they hadn't been out very long with an ecs kit and I don't recall having any problems with the low rpm driveability using the maf..... not sure what size the charge pipe was where the maf was housed on that one our how it was positioned before or after bends.

  13. #13
    Senior Tuner LSxpwrdZ's Avatar
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    I've found it to be very tricky to get the edges to line up sometimes. To streamline this process I save my "smoothed" VE surface in Excel so I can play with and manipulate the zone boundaries then paste my VE table into the editor and "calculate" (generate coefficients) the VVE. I keep adjusting zone boundaries until my zone edges are a smooth transition. The smoother the VE surface is after you "calculate" the more stable fueling will be when running in SD only and transition across that zone into another.

    I think of the zones as a floating 3d curved tile. Making all those tiles meet each other as smoothly as possible while still keeping the calculated surface as close on fueling is key.
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    wow your coolant temp was 220f anychance you swapping in a 160F tstat

  15. #15
    Quote Originally Posted by Tick View Post
    I figure the smaller diameter pipe will do more for our issue than the straightener, but I'd still like to figure out the vve. Have you successfully tuned any gen 5 engine equipped vehicles in speed density? I'm sure people out there somewhere have to be tuning the vve in these things, we just haven't had many come through our shop but they are starting to show up now.

    I tuned a 2014 when they hadn't been out very long with an ecs kit and I don't recall having any problems with the low rpm driveability using the maf..... not sure what size the charge pipe was where the maf was housed on that one our how it was positioned before or after bends.
    In early development I was sure the 4" pipe was the way to go so as to avoid having to scale the MAF so much. As it turns out the 3 1/2" pipe is smoother but requires scaling the MAF nearly 30%. The 3 1/2" with the honeycomb is as smooth as I can get it. The bends are as far away from the MAF as is possible within the confines of the C7 engine bay. I even had new silicone hoses made with a more gradual transition from 3" to 3 1/2". If anyone has any suggestions beyond that, I'm all ears.
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  16. #16
    Advanced Tuner Redline MS's Avatar
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    Quote Originally Posted by Tick View Post
    I'm working on a 2015 base corvette with an A&A supercharger system. The maf dialed in fine at wot and the car is making about 600 rwhp with nothing more than the kit at around 7.5 lbs of boost and an alky control system. However the car drove horribly at part throttle/light load and low rpm which I feel is the due to the 4" charge pipe and the location of the maf before and after a bend.

    So, I'm trying to tune the vve and I'm not having much luck. Up to this point, everything I've tuned with vve was done using the old 2.24 version of software with the bluecat tool and never had a problem. Now I'm using version 3 software for the first time and using the built in ve tool to dial things in and I'm not having any luck.

    It seems that we have a terrible lean spike when we cross the rpm zone 2-3. I've change the rpm setting for that zone and our lean spot moved with the rpm setting we changed.

    I know with the Bluecat tool it would change map and rpm zones automatically but this program doesn't. It would seem logical to change the map/baro ratio zones to something to fit our new map sensor but what reason is there behind tuning the rpm zones? I do have the baro sensor separate from the map sensor now also.

    I also just realized that changing the zone settings will change the entire look of the ve table itself? What am I missing in terms of the whole process of tuning the vve using this new program on a gen 5 engine/vehicle?

    I changed the rpm and map/baro scaling to fit our intended ranges.... I downloaded a tune file for a c7 z06 and noticed that even it does not go to a very high map/baro ratio, it only went to something like a 1.3. Why would that be the case and maybe even a more elementary question I have is why does the ve that is generated on a stock car always look so screwed up? All of the earlier stuff I have tuned with the bluecat tool I just put in the basic shape and values for the ve that I thought made sense and worked from that dialing in my afr error and everything always went smoothly. In order to dial this thing in using the fuel trims or the afr error from my wideband would lead to around a 25% increase in ve at the rpm zone 2-3 boundary.

    I have copied and pasted the generated ve from the intake manifold runner closed to the intake manifold runner open values also to make sure they are both the same.

    Any advice on what step I'm missing in this process or how and why the rpm zones would be adjusted would be much appreciated!
    I've mentioned it several times but the background math in how HPT converts to VVE back to coefficients is wrong. I wish they would go back through and fix it as its causes a lot of chasing your tail...
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  17. #17
    Senior Tuner LSxpwrdZ's Avatar
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    Quote Originally Posted by Redline MS View Post
    I've mentioned it several times but the background math in how HPT converts to VVE back to coefficients is wrong. I wish they would go back through and fix it as its causes a lot of chasing your tail...
    I've often wondered how well the back calculation is especially on the Gen5's. I find it very odd that a factory VE surface would truly be as choppy and uneven as it is yet keep a very stable GMVE with transition between zones.
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  18. #18
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    Highly suggested exercise to verify your math: run the stock numbers through the model (you think) the VVE calcs use. if you end up witha different surface, then the model is off.

  19. #19
    HP Tuners Owner Keith@HPTuners's Avatar
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    Quote Originally Posted by Redline MS View Post
    I've mentioned it several times but the background math in how HPT converts to VVE back to coefficients is wrong. I wish they would go back through and fix it as its causes a lot of chasing your tail...
    How are you determining it's wrong?
    We got this guy Not Sure, ...

  20. #20
    Senior Tuner Higgs Boson's Avatar
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    Quote Originally Posted by redhardsupra View Post
    Highly suggested exercise to verify your math: run the stock numbers through the model (you think) the VVE calcs use. if you end up witha different surface, then the model is off.
    is there a gen v update to the tool?