Hi,

Since stock, my LTFT idle and cruise were about 6-7% (idle mostly 4-6). I was using a conservative tune. After installing a few mods (Test-Pipe, IC, LICP, UICP, CAI...all from AMS), I have +12.5% LTFT idle and cruise.

What would be the best option?

- Try to lower injector scaling, in order to make LTFT lower;
- Flash that "trick" to stop Fuel Trims affecting WOT;

I use the car a lot in trackdays, with varying wheater conditions, since I usually race in different cities (differente temperatures, umidity, elevation);

Is there any other thing to do in order to make the car safer after installing the CAI? Until I am sure about this, I am avoiding going WOT, but I have a TrackDay next Sunday and it would be nice to be safe. Otherwise, I will remove the mods until a pro could remote tune my Evo.

Thank you,
Best regards,
Ziki

 

Recalibrate your MAF. If you injectors were scaled and calibrated correctly before, they aren't going to magically change to something else. However, the AMS cai has a drastically different mas calibration than stock. Fortunately, Cobb has already calibrated it on one of their publicly available maps, so you can just run theirs as a start point, and see how it does. It will likely work well enough to not have to mess with it. Here are all the values from 0.00 to 5.00 volts at stock resolution.
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.11 0.27 0.46 0.76 1.12 1.53 2.00 2.46 3.02 3.58 4.17 4.82 5.50 6.21 6.98 7.83 8.67 9.60 10.57 11.64 12.77 14.18 15.43 16.76 19.00 20.43 21.95 23.76 25.46 27.49 29.39 31.35 33.38 36.24 38.59 41.05 42.41 44.96 47.60 50.19 52.92 55.80 58.72 61.74 64.85 68.10 71.47 74.98 78.64 82.41 86.28 91.21 95.37 99.60 103.99 108.31 112.63 117.07 121.82 126.74 131.94 137.36 142.97 148.79 154.78 160.99 167.37 173.88 180.58 187.45 194.46 201.64 209.03 216.59 224.29 232.20 240.18 248.31 256.65 265.13 273.78 282.56 291.32 300.27 309.54 319.11 328.97 339.13 349.16 359.21 369.47 379.83 390.61 401.55 412.87 424.44 436.27 448.37 460.73 473.34 486.24 486.2

 

Wow, those numbers seem too high for me. I run an AMS intake too but those numbers are much higher than mine. I wonder what kinda loads are hit when using that MAF scaling.

 

I am not sure what load is hit. For this to work, it would require that your injectors be tuned correctly as well. Generally Cobb's maf calibrations tend to be dead on, so I would run this and if your trims are wacked, tune your injectors accordingly. If you aren't sure what settings your injectors should be at, I would start with the setting you get from the injector manufacturer. If you are using DW 800's or stock use cobbs injector settings. If you are using DW 1000s, use 975 scale and latencies of:
3.50/2.18/1.94/1.70/1.46/1.10/0.84.

 

I have stock injectors, and I am using EcuFlash. Should I rescale injectors/latency in some way before using the maf scale you have provided?

Thank you,
Ziki

 

If you are on stock injectors, I would not change their scaling at all. Load the maf calibration, reset you learned ecu parameters by disconecting your battery for 5 minutes, and log your fuel trims and maf voltage, and see what you are at. If your trims are less that +/-5% out, I would leave it, and monitor for a few days, and see what they settle out to before changing them.

 

Thank you kosmic. I am going to try it out.

Best regards,
Ziki

 

I would love to see your WOT logs after this is done, please post if possible

 

+1 curious to see the logs too

 

i wouldn't bother with my maf scaling and i would just decrease your global scaling until your trims are better. i wonder if that would make you go near static though.....

 

I have talked to some tuners and I have the impression there is not a single solution for this fuel trim adjustment. Some say you have to adjust maf scaling. Others say you just need to adjust injector scaling. Others say you have to change Injector Latency. And some say you might need to adjust all of them.

I have done a small python script to help calculating new maf tables according to http://www.***************/forums/sh...ad.php?t=18023. You provide your rom file, the EvoScan log (with MAFV, STFT and LTFT columns) and it will calculate a new maf table.

Is there a formula for adjusting injector scale and latency. I mean, I have read if you change latency by 0.1ms, the cruise LTFT would change by 10%. Is there such numbers for injector scale?

Btw, if I go to the injector adjustment route, should I adjust the scale or the latency, or both?

What about making some tweaks in injector scaling, in order to make the trims lower, then proceed to the maf remapping as a fine tune?

Another thing: At EcuFlash, the MAF tables are "MAF Compensation", "MAF Compensation #2" and "MAF Compensation #3", isnt it?

Thank you,
Ziki

 

You shouldn't have to adjust the injector settings, that is trying to take a short cut to fix the PITA process for MAF scaling. Adjusting injector settings (both scale & latency) will only make it possible to correct your fuel trims. The reason why you want to scale your MAF is not only to correct your fuel trims but mainly to hit the proper load cells that you should be in. Generally, if you increase the size of your MAF housing less airflow will be detected by the MAF sensor. This will mean you will be in the wrong (lower) load cells for all maps with a load axis.

 

I have done the MAF rescale procedure as stated in the previous link. I could bring my FT to < 2.0%, after 3 iteractions. They are better (smaller) than my stock values (6 to 7.5%).

The only problem I get now is that, sometimes, when I start the engine, the RPM go to low, almost dieing, then fluctuating again to higher values. I have rescaled the maf tables during the day (hotter) and such thing happened tonight (colder). I am not sure if temperature would make this. Is there something I could do (in ecuflash) in order to correct this?

Thank you,
Ziki

 

Did you reset your ECU after flashing with the new scaling? Whenever you change MAF or injector settings you have to reset the ECU or it never seems to fall into the correct place even after driving it for days. Unplug the ECU for about 5 seconds and plug it back in, that will reset your ECU. Also, do you have a wideband? When you car is idling funny, what does your AFR look like?

 

i'd be willing to bet they're super lean. when you STFT goes to 0 you enter open loop at idle. did you adjust the idle area of the fuel table to compensate for the changes you made to the MAF scaling?