OK, so I need to start looking into this.

KRKTE is for how long the injector stays open?
what is the injector latency map? and where?
MLHFM is for MAF scaling?  RS4 MAF values are slightly lower than stock S4..hmmmm

I know Tony has a little info to share once he reads this.

OK so i guess im on the correct path with KRKTE, oh yea forgot about the RS4's were all Bosch sensors, makes perfect sense.

ill look for the 5x1 maps tonight if i get a chance and post up what i find and where.

having issues finding these, care to take a looksee?  another set of eyes helps when staring at hex sometimes.  I did find TVUB  im using hbox

coool, thanks, lemme see if thats similar to my hbox, at least i got addys for us spec ecu now

KRKTE is used for idle and part throttle as well. But during idle and part throttle you have O2 sensor feedback, so the injection time is constantly adapting. Make SMALL adjustments to KRKTE and keep testing; you can drive yourself crazy if you make large adjustments and keep overshooting. Keep an eye on long term fuel trims; idle trim means you need to adjust latency; part throttle trim means you need to adjust KRKTE. You can use the short term trims, but remember they will constantly fluctuate as the AFR oscillates between rich and lean in idle and part throttle.

As for scaling the MAF, you should try to get the injectors dialed in perfectly before dealing with the MAF. So either use stock injectors and a different MAF, or get your new injectors tuned with a stock MAF, and then switch to a different MAF. If you try to tune the MAF and injectors at the same time you can do it, but you are not tuning them for actual values; you are tuning them to be in the correct relation to each other. You can set your injector scale (KRKTE) and you MAF scale to the theoretically correct values, and go from there. If you end up underscaling the MAF though, you will have abnormally low load values. Some tuners prefer to work this way, since you don't have to correct a lot of the maps dealing with load limits. But if load reads abnormally low, then all maps that protect your car under high load, are essentially disabled until you retune them. Not to mention it sucks not being able to compare MAF and load readings from your logs to other cars anymore.

If you log your car with a stock MAF and record MAF air mass, MAP, and RPM. Then you should be able to switch to a new MAF and correctly rescale if by comparing a before and after log. You would just need to match up the two logs and see what the difference in the MAF reading is, when the MAP and RPM are the same.

Currently I am running Siemens 630cc injectors and a stock MAF while I get all of my low level fueling settings sorted out. In the B5 S4 you should be able to get up to around 400hp before you reach the flow limits of the stock MAF.

Does that help at all?

If you change the size of the MAF, you should just scale the 512x1 map up or down based on the change in cross sectional area. Unless you have a flow bench, that is the best you can do. If you are sure your fueling variables are correct, then you can use the short term fuel trims to determine if certain parts of the 512x1 map are scaled wrong. But this is more work than I have seen any tuner out there do.

So if you are running a larger MAF, scale the whole 512x1 map by (New Area / Old Area). This will tell the ECU that more air is flowing into the engine for a given MAF voltage. There is also an air mass correction map that allow you to scale the air mass reading based on RPM and air mass. You would use this if at certain RPMs and air mass you get abnormal turbulence in the MAF tube and need to correct for it. Some tuners also use this correction map to tweak the idle AFR.

Just to let everyone know what I have been doing. My S4 has K04 turbos, Siemens 630cc injectors, stock MAF. I started with a stock tune that had the fuel injector scale corrected for the larger injectors. I then did numerous 10 to 20 minute test drives giving the car time to learn the response of the new fuel injectors. During the drive I would try to have idle, part load, and WOT, and multiple types of driving types. After each test drive I would read the long term idle fuel trim and the long term partial load fuel trim. Using those trim numbers I would adjust the fuel injector scaling and fuel injector latency map.

The long term partial load fuel trim is a percentage correction of the reference load for fuel injection. So if the long term partial load fuel trim is 5%, that means the car is scaling up the load by 5% to make the car run richer. The fuel injector scale is in (ms injection time / % load). So to adjust for the car needing to add 5% fuel to run at the correct AFR, I would then scale up the fuel injector scale by 5%.

The long term idle fuel trim is also a percentage correction of the reference load for fuel injection. So if it is -1% that means that the car wants 1% less fuel at idle. To adjust this change the injector latency map. The latency map is in ms, not ms/% like injector scale. To convert the percent fuel trim into a ms value you have to multiply by the fuel injector scale. You take the fuel injector scale in ms/% times the long term idle fuel trim in % and that gives you the long term idle fuel trim in ms. Then you use that value and either add it or subtract it from your injector latency map.

Keep repeating the test drives and tweaking of the injector scale and injector latency until the long term trims are sufficiently close to zero.

Hope that helps.

Correct. It is easier to change one part at a time, since you then only have one variable to deal with.