This is 100% correct. However, it doesn't say to scale lower than the actual value to keep duty cycle down. You scale lower because of how the ECU calculates fuel for closed loop. If you were to scale, say, 650 cc injectors at 650, you would be initially lean and the ECU would increase fuel trims to compensate. By lowering that value, you can keep trims near 100 (0).

 

EvoScan should be between 90 and 110, and Mitsulogger should be between -10 and 10.

(The quote you posted says within 5%, but I've found that a dirty air filter can skew the trims by 15% or more, so i think 10% is okay)

 

alright that makes sence, thanks for clearing that up for me. so if i click on my LTFT low mid and high what should i see on the maps. cuz im looking at them right now

 

and if they are off what would this cause?

 

If they get too far off, the ECU can no longer control the fuel mix in closed loop. Also, on the Evo's at least, the fuel trims will sometime affect open loop (WOT) fueling as well. this is a pain because the trims reset after flashing. So, you tune your AFRs dead on after a couple of flashes, but then the trims stack up and your AFR at WOT changes.

 

so all of the fuel trims should be within that 90-110? low mid and high?

 

Yes. The High trim is usually stays at 100 in EvoScan because it applies changes at airflow values so high that you are usually in open loop when they occur.

** This quote was referring to MAF scaling and not injector scaling ... both can affect fuel trims. **

 

SO is tis in reference to maf modding? like the removal of the restricor plate

 

alright, well that sucks then. haha cuz mine are off, but i havent seen anything telling me that they were off in my afrs at wot. whats the best way to change it? rescale to 400? and redue the fuel maps? or rescale, log the stock maps back on then edit them? im confused. thanks bubble

 

Modifying the intake box/filter/etc can throw off MAF readings which can throw off the fuel trims (the MAF reading is the "Air" part of the "Air to Fuel" Ratio of course). The Hz values mentioned relate to where the fuel trims take effect per the MAF scaling table. The stock MAF scaling table isn't in Hz, but you can simply divide the left column values by 10 to get a ball park Hz value.

So, if your trims are off, it could be caused by injectors or MAF readings. the only way to know is to use known injector scalings and adjust the MAF scaling, or adjust MAF scaling with the stock injectors and then add your larger injectors and scale them as well. This makes for a tricky predicament, because lots of stuff is based on that MAF reading, and if you adjust your injector scaling to compensate for what is really an airflow issue you could likely have a problem you are just covering up.

 

That's because trims (for the most part) only affect closed loop. As I said, you can tune the map to get rid of the rich condition in open loop, but correcting it in closed loop can only be done by correctly scaling the injectors.

The fix is to set a conservative fuel map, perhaps based on the stock map -2 AFR or so. Then, scale your injectors per the ECUFlash injector scaling tutorial. After that is done, tune your fuel map.

Just a note: it takes a while for the fuel trims to settle where they want to be. So, after the initial scaling, drive around for a couple of days before checking the trims again. The trims will only move while you are in closed loop, so watch the O2 Feedback Trim to get a feel of where your crossover point is. If you use my gauge set with EvoScan it has a closed loop indicator just above the AFR value.

 

alright thanks for the help

 

No problem. I do what I can.

 

alright so this is my plan. just to clearify before i start doing it.
im going to leave my moded timing maps because they are fine.?
im putting stock fuel maps (low and high) back on and droping all values 2 afrs
scale injectors to 390
then go out and tune the fuel maps?

 

if 390 is about 15% below your actual injector size, then yes. Read some of the threads on injector scaling before heading out to try this. You may need to adjust the latency as well to get the mid fuel trims in check. You aren't going too big so it might not be an issue.

Just so we are clear, 2 AFR is 2.0. That should put most of the WOT values at ~10.0. If your actual AFRs are below 10.0:1, abort and bump up the fuel map ... there is a such thing as too rich. If you have an FMU installed, you might want to put the fuel map around 11.0 since it will be adding fuel as well.

Then, just tune like you normally would, of course logging knock. And you might want to make a pass with real time gauges running to catch any knock early. You may need to adjust timing slightly to avoid knock during tuning, but if you get the AFR's to match what they were before, you will not have to change the timing map.