Just wanted to say thanks for this post... and highlight the importance of doing this "last step" in my transition from stock injectors to the EV14s (298s, Ford Racing GT500). I've owned my car for 5 years and have been refining my tune, with lots of help from ddilenger, S4Wiki and Nefmoto posts. My hardware changes (bigger turbos, injectors, fueling upgrade, RS4 MAF, etc) were completed years ago. Cold surging was my last, lingering issue and I think I've finally resolved it.
I had bucking issues during cold start/warm up phase, struggling with them for quite some time. My warm engine tune is spot on, with RKAT and FRA both with trims of +/- 1%, varying some with air temps and different fuel, but never more than +/-3%. I initially assumed it was an enrichment problem (since I was trying to accelerate when encountering the lean out). Seems rational, right? I fucked with MAF curves, FKKVS, idle torque curves and KFBAKL to no avail. I only recently realized my lean out during warm up at engine speeds above idle was actually occurring during a decreasing load situation (load at cold idle is above the tip-in load). I know how weird this sounds, but my load decreased when coming off cold idle (1,000 rpm) and engaging 1st gear or accelerating in 2nd gear from a rolling idle (rpm ranging from 800 to 1500 or so). So, load driven accel enrichment, KFBAKL, was useless and the other steady state items I played with weren't appropriate for this transient condition. Only increasing KFWWL (appears to) ameliorate the issue.
After increasing KFWWL and increasing the factory KFFWLW weighting curves at low load levels (low loads drop the weighting to almost zero), I think I might have actually addressed the issue. First attempt today showed much improvement, but I need to test again with higher values. Logs show lean out is still occurring, but it isn't as extreme and I didn't "feel" the car buck/surge like I've grown accustomed to experiencing.
Strange enough, fixing the warm up curves, allowed me to set KFBAKL back to stock levels (much lower values than I had been running). And acceleration was smoother for it.
I'm now thinking you only need to alter KRKTE, TVUB, FKKVS/FKKVSNWS and KFWWL/KFFWLW when converting to EV14s. The EV14s are so linear that FKKVS only needs moderate changes (from 1.00) at off idle injection (2 to 4 ms or so) and low rpms (1000 to 1500 or so). Hell, I might not require that with higher KFWWL values. KFBAKL tuning might offer throttle response improvements, but my tip-in lean out seems to be no worse than 5%, lasting no more than a fraction of a second, using stock values. So, big changes (50%+) to KFBAKL, like I've seen suggested in some posts here, shouldn't be necessary. Of course, I've only tuned my car, a 2001 Porsche 996 Turbo -- a sample size of 1. Your experience might be different, but I'll bet the turbo Audis using ME7 might be similar.
So after all this... A big thanks to nehalem regarding his following post, which pointed me in the right direction.
Sup players! Nehalem back again with your rock-star EV14 injector update. No doubt, Santa arrived early this year!
Lol, anyways. For the standard injectors, here's the deal. EV14 52# @ 3-bar / 60# @ 4-bar. Run the following:
KRKTE: 0.05495
TVUB: 2.5203 1.2695 1.0081 0.8881 0.7654
The elite trick:
KFFWL_0_A / KFFWL_1_A: Multiply the entire table by 1.10, or a 10% increase. Could be more or less, but I've found 10% to work quite well so far. Obv, I'll update as I continue to tune. Car starts right up and doesn't hesitate very much during cold operations. You'd obviously be an idiot if you go testing the car's power while the engine is cold. What I do know is that this trick restores most of the car's cold-temperature smoothness and eliminates the nasty bucking we all have grown to know and hate. My theory, in fact many people's theory, is that the characteristic bucking occurs because the car's electronic throttle interrupts and retards timing and throttle-plate angle, which to the driver feels super-non-linear because there isn't a physical cable connecting your foot and the throttle. Thus it's really an issue of "expected" versus "perceived" acceleration, for you HCI (human computer interaction) experts.
Therefore, you can't just "press the gas" more like you would on a cabled throttle [or an old / antique / carbed] car. Basically, without this trick, the incorrectly calibrated cold start of the engine (read: overly lean AFR) makes the response feel like the car is straight up terrible to drive until the operating temperature raises a bit. The worst part is that the closed-loop lambda operations turn the leanness into compensated richness, and thus the fueling variance of cold-starts without this trick straight up sucks. It sucks, got that everyone, it blows huge dongage. Use this trick. [or whatever "trick" you like to use, just sayin.]
One last bit:
KFZWWLRL: If you run advanced timing, like the baller we all know you are, then you probably want to *double* the warmup timing retardation chart. But hey, you know your setup, and it's your engine.
KFLF, FKKVS, KFKHFM are still stock M-box.
OK home stars. Knowledge is power. Fly high young jedis. Dr Brown out.
p.s. I run the Stock MAF / Stock Airbox / Stock Bosch MAF sensor from the early model A-box. M.Y. 2000 car.
