Boost Compensation tuning explained (again) MicroSecBit too!

[SA]

Where/how do I change my boost fuel correct table ? Looking at the other boost comp thread I think I need something above and below the "zero" line. I would love to see some other folks boost fuel table and throttle inj corr tables.
BLKMGK, if you want me to post the attachments for you just e-mail them to me. tarmour@catt.com

There's also a "pressure compensated" basemap provided by AEM for the Vipers.  Should already be in your Dodge Startup Calibrations folder.  Pressure comp worked very well on all the stock or slightly modded Viper motors I've tuned.  It didn't work in one case where the motor had a REALLY nasty cam and VERY high compression while tuning on an engine dyno.  It may have come around eventually but I reverted back to 3D mapping and the tuning went a lot smoother.  I'm sure the dyno loading was affecting the results too.  

It all comes down to personal preference.  Use what works best for you.  There's always more than one way to skin the cat.

SA

[blown1]

Thanks SA, I had seen that early in the game and had no clue what it was. Still though, in a boosted application don't I need negative and positive numbers in the boost fuel correct table ? How do I get positive numbers ?

[barrydklein]

Just drag the line upward with your mouse and the line will go into positive terratory.

Barry

[SA]

Just drag the line upward with your mouse and the line will go into positive terratory.

Barry

...or hit "S" and change it to table view then type whatever value you want into each spot.  Also remember the highlight... right click...and calculate function.  Comes in handy here.

SA

[blown1]

Well $hit, thanks guys. I swear I was just playing in the table view, but I was looking at what BLKMGK sent me and it was already there. Works fine...duh.

p.s. I hope SA isn't charging me overtime  

[BLKMGK]

Well $hit, thanks guys. I swear I was just playing in the table view, but I was looking at what BLKMGK sent me and it was already there. Works fine...duh.

p.s. I hope SA isn't charging me overtime  

He also spoted a HUGE error in my Boost Comp table when he graphed it. At 1.5BAR of boost it went to NEGATIVE 97%!   No other map in my "collection" has this that I've found so far. That one is actually a conversion from a later beta DOWN to 1.11. When I have time and it's not so late I'll try doing another and see if this error crept in during conversion. Already contacted one person I sent this mapping to - very scary to have missed that!

[KILURV8]

Can anyone post a picture of their injector mod table/Graph just so I can get an idea.  I understand absolutly everything that BLKMGK wrote excep the injector mod stuff.  I have to read it through a couple more times.  I understand what it is for, but dont quite grasp what it should look like when all is said and done.

[WadZii]

http://forum.aempower.com/bbs/viewtopic.php?t=11428

check out that cal... good example

[MP]

Here's an example picture for the Fuel Map, Boost Fuel Correct, and Throttle Inj Correct tables for Boost Comp Mapping.

[fperra]

If I set up the boost fuel correction table for a 3 bar map (-14.4 to 30.08 psi), can I then adjust the max range on the fuel map to reflect the max boost I plan to run. I only want a max boost of 20 psi, so if I adjust the fuel map to -14.4psi to 25 psi (a little headroom for boost creep), is this OK? It seems to me that this would give a little better resolution on the fuel and ignition map.

[blown1]

If you look at a Full Boost Comp'd mapping you will see that all fuel columns are the same vertically.  This is setup usually so that say 100KPA is a "zero point" - no change (the zero point can be anywhere you choose). But 200KPA effects a +100% change in fuel and 0KPA is a -100% change in fueling. Points in between are linear. Making sense so far?

Now - you can Boost Comp a mapping that's done cell by cell just by applying those % changes to the existing map.
Okay, go do a WOT pull at the lowest load value your W/G will allow - easy if it's a N/A motor! Tune that load row to whatever A/F you need WOT and make the cells above and below that load the same so there's no interpolation.

  I'm not understanding enough to know where to start with my table.....I know the columns will be the same, but where do I get my numbers from ? If my WOT boost from 2500 -6000 rpm is 8psi up to 10 psi .... then I take an average of the 7.95 row and the 9.47 row....average them and that would be placed in all the columns Just use the 9.47 row ?

Current map:


Boost comp:


Boost comp graph





   Also, what number should be at the top of my boost fuel correct table ? I'm still not clear on what the "percentage" numbers on the left side of the table represent. My "guess":  If I use max boost to start the map  then that would be 100% so my table should top out at around 140% Is there a way to change the load on the table ?

[mx5]

then I take an average of the 7.95 row and the 9.47 row....average them and that would be placed in all the columns Just use the 9.47 row ?

Either pick the 7.95 or 9.47 one (i.e. the one who think is tuned better). Then scale the numbers down (same principle as boost comp) to be at 0psi (100kPa) and put the scaled numbers in the new boost comp map (that's going to be your row). the goal is when the numbers go through the boost comp table index (for 7.95 or 9.47) to get as final result your original numbers.  Switch (at least temporary) the load to kPa - it is much easier to calculate in the metric units!

Of course this boost comp row (your boost comp map) is just initial one. You will start fine tuning/polishing it from there

[blown1]

If I set up the boost fuel correction table for a 3 bar map (-14.4 to 30.08 psi), can I then adjust the max range on the fuel map to reflect the max boost I plan to run. I only want a max boost of 20 psi, so if I adjust the fuel map to -14.4psi to 25 psi (a little headroom for boost creep), is this OK? It seems to me that this would give a little better resolution on the fuel and ignition map.

I "think" you can. Then you would need to have the line on the boost fuel correction table cross 100% directly above whatever boost you used to create your boost corrected fuel map. If you look at my tables, that is what mine would be like......It would be nice if the load on the on the boost fuel table could be set up to match the actual load breakpoints that we choose.

NOTE: This is just my stab at the correct answer. I'm learning this too.

[blown1]

then I take an average of the 7.95 row and the 9.47 row....average them and that would be placed in all the columns Just use the 9.47 row ?

Either pick the 7.95 or 9.47 one (i.e. the one who think is tuned better). Then scale the numbers down (same principle as boost comp) to be at 0psi (100kPa) and put the scaled numbers in the new boost comp map (that's going to be your row). the goal is when the numbers go through the boost comp table index (for 7.95 or 9.47) to get as final result your original numbers.  Switch (at least temporary) the load to kPa - it is much easier to calculate in the metric units!

Of course this boost comp row (your boost comp map) is just initial one. You will start fine tuning/polishing it from there

When you say scale down, I'm not understanding.  Say at 9.47 psi I have 18.1  ....... what would that scale to ?
 
In picking the "row", there may only be a few cells that are used in that row meaning only those cells used/hit will be correctly tuned...other cells in that same row will have an incorrect tune Maybe I need to look at this again after a good nights sleep  

p.s.  If I change to kpa......I may really be confused  

Edit:  So 9.47 psi = 166.57kpa so the scaled 18.1 @ 100kpa = 10.87 ?? This has to be done for each column ?  ?

[Alstare]

Honestly what shape of your Ve table initially is not that important, since that's what your going to be "tuning" with your WOT runs, it just gets you closer to start out with and keeps you in the area.

I usually just grab a semi tuned load ROW off there existing conventional map or a row off a base map for the car and then copy it up and down all the colums.  Then I just get the car to idle with an AFR at what I want to target by moving the entire Ve map up or down to get it in the range.

Then just make a few cut short, highly monitored WOT pulls at the lowest load you can maintain to make sure the AFR is in the ball park, then start the full out tuning process from there.

The hardest part seems to be just getting the Ve table in the initial range, the rest resembles a likeness to tuing a vafc...