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brain damage, setting up main VE vs RPM vs MAP histogram in HPT
so I'm trying to level up my tuning from "total noob" to "regular noob"
and i'd like to make more use of the histograms, namely setting up a histo to match the main VE table in the editor and an AFR% (or rather lambda %) error table.
with the primary VE vs RPM vs MAP i'm having trouble defining a parameter for the VE in % ( think thats what the editor table uses)
I can get it in gram/cyl...but for some reason that's hard for me to grasp (if you have a short sweet explanation of that, please share)
I think I have the AFR error % set but will need more testing.
lol I struggled with this all weekend. Never could get it to work. Just displays the afr instead of the eq ratio %. Read a million threads and how to's. In for info
Here you go, you should be able to look up the MATH when you setup the graph. If you look at the filter section I have filtered anything out that is greater than 13.0 commanded AFR. As I was using the WB to tune WOT only I did not want the readings for the part throttle. You can use the filters to your advantage and isolate the data you want.
Doug,
Histograms are invaluable.
Since you live in my area, I'd be more than happy to have you over and show you the ropes.
Ron
wow Ron That'd be great! I'm approaching the point where my questions have questions!
Originally Posted by JohnDaMan
Here you go, you should be able to look up the MATH when you setup the graph. If you look at the filter section I have filtered anything out that is greater than 13.0 commanded AFR. As I was using the WB to tune WOT only I did not want the readings for the part throttle. You can use the filters to your advantage and isolate the data you want.
Histograms are what make or break a tuner. Once you know how to log what you want to see you can adjust it. If you can't log the issue, you can't fix it.
Really good tuners/experienced tuners have a lot of histograms they can apply to a plethora of channel logging data.
One of the craziest I know is using a MAF to populate the VE table. Which, if you tune, you know you can set the MAF pretty quickly on the dyno hitting each cell. And it's a lot easier than trying to hit each VE cell. But then you can populate the VE table at the same time by solving for the correct equation since it's that't just calculated airflow and you are logging actual airflow through the motor. And then of course you check that by going SD and see if the wideband agrees still.
Anyway, I was lucky enough to find a tuning mentor over on the Corvette site 5 years ago. Little did I know then I'd be doing this for a living. Well sort of. I'm retired and this pays the bills and gives me something to do.
Always happy to help the new guys.
I'm not the best tuner, but I work hard at it and learn something new all the time. But then, I tune mostly Dodges.......
no maf on the turbo truck. but I am also tuning my '66 long bed c10 and it's been kinda tough to get the VE really nice everywhere (in speed density currently, will back on the maf after a little more tuning) and the idea of using the maf to populate the VE never occurred to me.
You'd just need a MAF for the streetable cells. WOT you're only hitting a narrow group from like 80kPa and up on a non-boosted car. But you hit those on the dyno. The cells from say 30kPa to 75kPa from 1200-4800 for driving around part throttle are tougher to get to. On a loaded dyno, it's easy to vary the load to see all the different cells. But on a dynojet, it's harder. Which is why you have to street tune those cars... but you still don't hit all the adjacent cells that can affect fueling unless you have a lot of hills around to lug up and down.
The MAF trick gets all the cells calculated out... so you may need to do some tweaking on it, but it'll be much closer.
It's a lot easier to do this with EFILive vs HPT. I haven't tried with v3. But v2 was pretty much a nightmare to build the equation for a Gen III PCM. It was missing PIDs to complete the equation...
There are a lot of cells in the VE table that are simply impossible to hit.
For instance....400rpm and 100kpa.
Stick shift cars make it easier to hit more cells for sure.
I suppose an auto with the converter locked could get close.
Stalled auto, forget it. The drive around area will be dictated by the stall speed.
Add a turbo and try to hit those 80-110 kpa cells. It will light off into boost and blow right past them.
Since there is a formula to convert MAF readings into VE table numbers, perhaps you can share it?
cylinder fill airmass = m[g] = MAF[g/s] / RPM * 15
( where 15 = 120/#cyl )
then convert mass to volume by dividing by air's density;
then convert to fraction of actual volume by dividing by cylinder volume;
then convert to % by multiplying by 100.
in EFILive we can just convert MAF straight to VE in native units like this:
VE[g*K/kPa] = MAF[g/s] * DAT[K] / MAP [kPa] / RPM * 15
where DAT is the dynamic/blended air temperature lookup.
Looks like EFI live has some nice functionality that HPT simply doesn't have.
We don't have access to DAT as far as I know.
I appreciate the explanation.
I tune lots of Dodge Hemis. They are all SD tunes. Dodge doesn't use a MAF.
I tune these on a loaded dyno (can be very hard on the car.....melting wiring)
I then test extensively on the street and always end up with large changes to the VE table.
WOT tracks nicely though.
04-24-2017, 07:47 AM
brain damage, setting up main VE vs RPM vs MAP histogram in HPT 
