RPM Zone Boundaries

[ns158sl]

Does anyone have a clear way to address zone boundaries. I spent quite awhile dialing in this VVE on a dyno. I can't say I love the way it looks. I don't want to spend much more on dyno time until I have a decent way to either lower or raise the boundary RPMs. My trims are within 2 percent or better everywhere besides a couple 4 cell quadrants. Another question would be, should I care what it looks like if the trims are becoming 0 anyways?

Thanks
Eric

[Alvin]

If you post the file I'll smooth it out for you.

I use a tool that we created and is not available for public or else I'd tell you how.

[ns158sl]

Holy crap thanks Alvin!

[Alvin]

here you go

Dyno Calibration VVE.2.hptCapture.JPG

[Alvin]

You should be using manifold switch open btw. your first screen shot was closed. I don't know any V8 GM platforms that don't ONLY use the OPEN table.

[ns158sl]

Oh wow, Thank you! Good to know! I can never remember which one to use so just copy and paste one to the other.

[TheMechanic]

here you go

Dyno Calibration VVE.2.hptCapture.JPG

What the.... WOW nice. That's a heck of a nice program.

[ns158sl]

So I had a chance to try a little bit of tuning on the dyno. Trims are off close to 8 percent, which is fine, problem is it is dragging the contours/peaks same way only to the new breakpoint? Am I over looking something? I am tuning with smokeshows formula so maybe Im getting MAF reversion and throwing the VE off? Ill try and disable the MAF tomorrow and see what happens. Thanks again!!

[Alvin]

I'm not a fan of backing out VE from MAF.

[TheMechanic]

I'm not a fan of backing out VE from MAF.

What do you mean "backing out VE from MAF"? I'm genuinely curious.

[Alvin]

There are people who instead of failing the MAF and tuning speed density they try to use the MAF/Dynamic airflow to backout VE numbers. There is a crazy long thread around here were people are trying to work out how to do with with filters and what not. In my opinion making more work for themselves than doing it directly.

I'll do it in very seldom situations like cars that won't run or have another problems with a failed maf like late late gen 5 stuff. But failing the MAF and getting VE right takes maybe 3 flashes? Then you know it is good and can stand on solid ground by itself.

[GHuggins]

He's talking about using formulas like this one to correct the VE table. I use the MAF reading simply because that's how the OE does it on the newer ones, which is why I personally don't see a problem with it except for if you have bad cam reversion. Bad cam reversion is the only reason I've found that makes this not work. The OE uses airflow error based off of the MAF reading to apply a correction factor to the VE and map models on the newer stuff so again I don't see a problem with doing what the OE already does. Cam reversion will completely throw off the MAF reading and if that's happening then the reading you're using to correct the VE table will then be thrown off. I've personally found issues with using dynamic airflow and have stopped using that. Primarily because of torque control routines for decel on the newer ones and dynamic having transients included into it causing it to want to add fuel in the decel regions. Otherwise, I don't see a big issue with it and it may even be something I'm doing wrong in the setup process causing the trouble there. Then from what I see mainly just the stage 3 cams or bigger will have problems with reversion to throw off the MAF readings. Usually "stage 2's" and under won't have a problem. I also don't like to make the VE tables that smooth. I prefer them to keep fuel right and not just look good, but again, that's just me. The way Alvin's program changes the boundaries I imagine might fix a decent amount of that...

As long as you don't have reversion to throw the MAF reading off then I haven't seen an issue back calculating the VE. In fact you can usually fail the MAF and get trims nearly identical to the errors that the formula shows you. Just what I've seen anyway...

This is Cringer's dyn equation just using MAF instead. It's simpler than my older MAF formula, so this is what I use.

(([16.71]+([16.71]*([50116.156]/100))-[2311.71])/[2311.71]*100

[ns158sl]

Good to know. I had to go get gas and working out EVAP bugs still, then Ill try again.

Im using this formula.

(([16.71.avg(200)]*(1+(.01*[6.156.avg(200)]+.01*[8.156.avg(200)])/2)-[50070.56.avg(200)]/60*4*[50030.92.avg(200)]*[2312.avg(200)]/[2126.240.avg(200)])/([50070.56.avg(200)]/60*4*[50030.92.avg(200)]*[2312.avg(200)]/[2126.240.avg(200)]))*100

I don't need to use all the averaging being this was on a dyno, but either way.

Thanks again for all the input guys. Still trying to figure out if there is a method to the madness other than calibrate vve, change a boundary whether RPM or MAP, then recalibrate vve, lol. I find it odd GM uses the same breakpoints from a truck cal to a LS7. So maybe a guy shouldnt care about it?

[GHuggins]

Good to know. I had to go get gas and working out EVAP bugs still, then Ill try again.

Im using this formula.

(([16.71.avg(200)]*(1+(.01*[6.156.avg(200)]+.01*[8.156.avg(200)])/2)-[50070.56.avg(200)]/60*4*[50030.92.avg(200)]*[2312.avg(200)]/[2126.240.avg(200)])/([50070.56.avg(200)]/60*4*[50030.92.avg(200)]*[2312.avg(200)]/[2126.240.avg(200)]))*100

I don't need to use all the averaging being this was on a dyno, but either way.

Thanks again for all the input guys. Still trying to figure out if there is a method to the madness other than calibrate vve, change a boundary whether RPM or MAP, then recalibrate vve, lol. I find it odd GM uses the same breakpoints from a truck cal to a LS7. So maybe a guy shouldnt care about it?

Don't even get me started with EVAP I've been in so many circles in regards to "its" correction factors throwing things off that I've gotten dizzy. LOL

Seriously though, a lot of people won't even consider the evaps propagation factor or how increasing airflow for a cam can throw off it's corrections due to the extra vacuum being applied to the system especially at idle. I've actually gone as far as having one customer test a half hole size orifice in the evap purge valve. Seems to have completely fixed its fuel skewing so far. Wish there was a table where I could just say to remove "this much fuel" for purge flow, but no one's found it yet.

[ns158sl]

Yeah, Ive already put in a new GM canister and vent solenoid. I am not throwing any faults but from a cold start it must be running a test around 160 degrees and usually the afr will plummet to 12:1, the idle will then oscillate and die. I thought this would of went away after dialing in the VVE and MAF on the dyno. Ill have to do some more troubleshooting, then search, then might have to start a new thread.

[GHuggins]

If you can cut the orifice size down to half in the purge valve it'll take care of a lot of that. Actually some of the problem I was chasing on some cammed gen V's interestingly enough. Not having stalling problems, but it would run it's test and cause the throttle to blip. Dialing the orifice back took care of a lot of it. Propagation factor is how long it takes the vapor to get into the cylinder. Not really sure what you would call the over richness caused by the excessive flow from the higher airflow at idle? Guess it's just a multiplier somewhere that nobodies found yet. Basically it would see cruise airflow at idle although the rpms aren't there causing things to get skewed. I haven't seen this issue yet on a gen 4.