Target AFR and Actual AFR
 

Guys,

I want to flash my ECU and use the xede as a boost controller only. I think I have the target timing exactly as I want it based on my xede adjusted timing.

I want to know if my target Fuel Map numbers will give me the actual AFRs that I want.

Here is the high octane fuel map that I have

https://www.evolutionm.net/forums/at...1&d=1172132785

And here are the actual AFRs that I want to hit

https://www.evolutionm.net/forums/at...1&d=1172132904

Would the numbers in the fuel map translate into the actual AFRs that I am currently getting?

What numbers should I put in the Fuel Map to get these actual AFR numbers?

TIA

Hey, you should just get rid of the xede, if your only gonna use it for boost control. Also glad to see your going to a flashed ECU. I think its better then a XEDE (I had one too, if you didnt know)

To your question, IIRC, those number dont always coralate perfectly with the actual AFR. Meaning, there no way for us to tell you what numbers will achive XX.X AFRs.

nj I could the xede offsets be used as a template ? the xede offsets the ECU fuel map by a % in a cell , if the ECU value is 9.6 and the xede changes it by 9% =10.5 ((9.6 x.09) + 9.6). It would be a very interesting test, it may not correlate directly since the xede does the offset by changing the maf values.

Typically, you would just treat the fuel map numbers as arbitrary numbers, much like the duty cycle numbers in some ECU maps. Then you have three basic 'charts'. You have your actual (what you are logging), you have your desired, and you have the ECU map.

The formula for a cell would then be something like:

newmap = desired / (actual / currentmap)

Look at 2500/90. Desired is 12.8 (12.76). Map is 14.3. Let's assume that when you log you get an actual of 13.9.

12.8 / (13.9 / 14.3) = 13.2

So, if 14.3 in the map gives you 13.9, 13.2 in the map should give you about 12.8.

The problem you have is that you are currently running a piggyback and your ECU table is way lean for your timing, etc. So, to get started you probably either need to adjust the table manually, with a fudge factor on the rich side, or try something like Jorge T suggests. Once you have a rough map, you should be able to fine tune it back to your 'target' (your actual with the piggyback), using the scheme above.

Good Luck,
-jjf

Why is ECUFlash better than the Xede? The Xede offers better resolution and also has decimal increments on the timing table for more fine tuning. IMO, the Xede is a good tool to fine tune the stock ECU.

You will have to load that fuel map and log with a wideband to find out what your actual AFR's will be. There are lots of variables besides your level of modification. Different engines run differently. There is no way to tell exactly what your actual AFR's will be until you run it and log it. AFR targets are arbitrary numbers and just targets. You will probably have to make some minor adjustments here and there if you've never run that fuel map but it doesnt look too far off although I dont really know what a VIII fuel map should look like. For a IX it would be a little lean at spool 3000 rpms load 160-260. Since VIII's spool a little later it may be just right.

I fully understand what you are saying, but given the level of experience that some in this forum have with flashing the ecu, you would think that there should be some rule of thumb.

For example, if you change the Target AFR by 0.2, what will the Actual AFR change by?

With the Xede for example, a 4% offset on the fuel map will move your AFR by a factor of 1. It is NOT a hard and fast rule, but a general guideline.

I am not asking for 100% accuracy here, but a GENERAL rule would do. I am just surprized that there is no such rule.

jfitzpat has given you the answer.

But if you want a rough rule of thumb then in your case a 0.2 adjustment will probably give about 0.23 change in AFR.

I still like the Xede too.

How does the xede have better resolution?? You can edit any map in ECUFlash for the same resolution

You right, one of the best features the Xede has over the ECU is the fact you can do decimal increment of timing. Besides that, I find the ECU to be better in everyway.

Also, in this situtation, where NJ is using the Xede for just boost control, it would seem like a better idea to ditch it and get a MBC, EBC or use ECU controlled boost control.

BTW, did you know Vishnu has made a replacement for the Xede. I dont know if theres been word here, but on the BMW forums, Shiv started using the Xede to tune 335i's, but has since made a new computer called the Proccede (basically an updated Xede with more features and opitions) to use on the 335i's. I believe Vishnu's business relationship with Chip Torque is over, but dont quote me.

In reality it's like this https://www.evolutionm.net/forums/sh...d.php?t=250353 and for the 8 it is perfectly fine and will still be supported.

The Xede uses a 10 bit ADC and allows full resolution offsets. Stock ecu maps values are 8bit.

d

No lean spool active, I have found that you can add about 1.44 to the value and be fairly close to WB AFR. If anything its a little low. Almost always its a direct correlation in change to effect. I havent noticed any big shifts (as in .5=1 or .75=1.5) and the small correction factors make this rule work for me. I used both a PLX and a NGK and was similar in my readings.

nj1266
i can see that you are using a screen shot from LogWorks2 software. x-axis is rpm and y axis is LOAD (i think this calculated load)

how can you calculate the load and use it as y-axis using LogWorks2?

i tried but i couldnt find? i searched but no luck:crap:

1. Log the necessary channels for the calculation using the OpenPort Plug in.
2. Use Tools/Calc to calculate the Load Trace (I've posted the calcs, but I can't remember if it was here or our support forum)
3. Use the calculated trace like any other when you create a new chart.

-jjf