Originally Posted by wadzii

Boost comp quickie how-to

First off read the boost compensation thread the OP put up a link to. Know what microbit/sec does but dont worry about it just yet.

I'm going to use screenshots of aem V1 software, v1 works exactly the same way, the tables names have changed very slightly but it's easy to figure out. The main difference in the v2 software is that when you change the load breakpoints they also change in the boost fuel trim table, in the v1 sofware they dont change. SO for VERSION 2 ONLY, IF YOU CHANGE LOAD BREAKPOINTS GO BACK TO THE BOOST FUEL TRIM TABLE AND FIX IT!!!!

here's what the aem v1 base fuel map for ap1 looks like. You can follow this to make a new map or convert your existing map to boost comp.



Since boost comp works by applying a trim based on fuel at atmospheric pressure we need to tell the ecu how much fuel the motor needs there. The main fuel map is where we do it. To start we'll take the 0psi/100kpa load row and copy that to the entire map. Simply highlight the 0psi row, ctrl-c, highlight the whole map, hit ctrl-v



Now thats done, lets go setup the boost fuel correction table. This table is set for the range of the map sensor and doesnt change. You'll find this table in the Fuel Trims template

To get the values take the lowest number on the Map as Load, then divide by 14.7. For a stock honda map sensor that means -13.9/14.7= -95. Then for the max value thats 10.94/14.7= 74 Then use the calculate function to draw a straight line (hit the letter M while viewing a graph to bring up the menu of things you can do)



last thing to setup is your throttle fuel trim. You'll find this table in the same template as boost fuel correct table. I have a custom template with the fuel map, ignition map and throttle correction on the same screen.

The throttle mod table is going to do sort of an s-curve. Usually this is a good place to start.




Now everything is set, time to tune. When you first start the car it'll probably be too rich or too lean to drive or whatnot, so increase or decrease the lower throttle values of the throttle inj corr table to get it where it'll idle/drive.

First thing we need to do is tune WIDE OPEN THROTLE. Remember the entire fuel strategy is based on WOT fuel. That what the fuel map is to us now, JUST a WOT Fuel map. If you are street tuning put the car in 3rd at a low rpm, go WOT just long enough for the afr to stabilize. Now adjust that rpm column, the whole column. Keep the fuel map flat. Keep doing this going higher and higher in the rpms. After about 3 WOT pulls you should be able to have the WOT fuel dialed in. Rule of thumb a 10% change in the fuel map will result in 1 point afr change. Need to go from 13:1 to 12:1, add 10% fuel. (hit M on the keyboard, then E, enter 110 in the box to add 10%, enter 90 to reduce fuel by 10%) The map will end up nice and smooth, there should be no huge changes between breakpoints. If the map looks "funny" or "ugly" its probably not right. You want the same afr at WOT from idle to redline. Turbo cars shoot for around 11.5:1, NA cars 12.5-13:1

Once you have wot dialed in its time for part throttle.

Best bet is to get on the highway get the car in 6th gear at a medium rpm.. 3500 or so. Adjust the throttle inj corr table so that at light throttle you are around 14-15:1 then have the afr taper up to your WOT afr as you approach WOT.

On boosted cars. DO NOT be alarmed if you are in boost at say 30-40% throttle and your afr is leaner than your wot afr. That is fine and a good thing. If you have an EGT you'll see that your egt's dont really go up even if you're in boost at part throttle. Fuel is there to keep egt's in check. This is one HUGE advantage of aem over kpro. You can lean the car at part throttle even in boost. Your plugs will last longer, your oil will last longer and you'll get much better milage.

Trust what you feel, at part throttle you dont need a specific afr. You want the car to drive good more than obtain a specific afr.

One last thing ... Idle fuel. So you've set your throttle mod on the highway, the car drives good, wot fuel is spot on, but at idle its too rich or too lean. Go to your advanced idle template and adjust the fuel offset vs rpm table. Keep the line flat, but move it up or down to get the fuel at idle right.