Porsche 996 Turbo - Upgraded from stock injectors with single conical spray pattern with 20 degree cone to (Bosch 298) injectors with dual cone spray pattern that is separated by 25 degrees. 

Steady state fuel trims are good (less than 3% throughout the MAF range) following TVUB and KRKTE changes.  WOT lambda is on target following KFLBTS changes.

Having a problem with partial throttle acceleration enrichment -- stuttering (lean out to 1.4 lambda momentarily) in low rpm range (1,200 to 2,500).  Think initial take-off and cruise shift points -- both under moderate load.  Worse when engine is cold soaked (initial start-up).

Need some advice regarding this issue from anyone that has encountered in their tuning.  I know I need to dial in at least some of the following tables:  WFRL, KFBAKL and KFABAK.  I'm logging and reviewing tip-in performance, but can't seem to make the right changes.  I've left WFRL stock since decel enrichment/enleanment is pretty good and focused on BAKL and ABAK.  I've progressively increased both significant amounts in the regions of concern, but the issue persists.  Increased short/long splits from OEM levels of 0.10 to as high as 0.35 and observed initial lambdas low (rich) enough to stall the motor off idle (below 0.7) -- that was not fun in traffic .  Scaled up OEM KFBAKL from warm engine levels of 0.13 (yes, that is right) to values over 3.00.   So, simply scaling my OEM curves up doesn't work (too rich at idle tip-in, too lean between 1500 and 2000 tip-in).  I'm now at the point that I'm testing these maps with "shapes" that are significantly different from OEM (putting a big hump in the middle rpm range - distorting the OEM declining exponential curve).

Just looking for some lessons learned by folks that have been down this path before...  especially after changing injectors with different spray patterns.  I'm using trial and error testing at this point to find proper values, but there must be a better way...

Read the FR section ESUK, but the application notes basically say calibrating tip in should be done on an engine dyno in a very controlled environment...  with a lot of test time to cover all the possible load changes. 

Thanks for sharing any insights.

Unless you haven't calibrated FKKVS properly in steady state - which needs doing on a load controlled Dyno, I would cut your loses and go for a more suitable injector. 

Rick

That can be used but you still need to reach all the breakpoints in order to tune them.

No it can't, but often issues are exaggerated by non linearity at small pulse widths so it needs to be perfect first.

My remaining tip-in (idle to off-idle) stuttering, which is really lean-out, appears to be mostly driven by the transient correction described in ESUK. 

My stock WFRL had much too low of a gradient at idle, so the total correction was too low.  That explained the "dull" tip-in performance -- I was always leaning out, even with the stock injectors.  Per the FR, idle gradient is supposed to be about 1/3rd of WOT gradient.  Making this change provided some improvement.  Now I'm struggling with VAKL,BAKL,AVAK,ABAK...  Getting the short vs long splits right is challenging.  Lots of moving parts in the transients...  I can see the value of a controlled dyno environment for transient characterization.  Steady state, like FKKVS, is pretty easy to get sufficiently close with "real world" logging.  Making progress, but it is tedious.

Question...  Porsche disabled the transient adaptation described in ESUKA.  Any idea why they would do that?  What value do you Audi guys have for CUKA?  Disabled = 0.  Fully enabled = 15.  Also, what value do you have for RKUKKLU?  Porsche set it at 100%, but FR suggests 30%.  The Porsche engineers probably had good reasons for deviating from the recommended values, but reverse engineering their logic is not intuitive whatsoever.

I set CUKA to 15 and made sure the parameters in ESUKA were set to the recommended values.  Seemed to smooth things out at cruise RPMs, but not at idle tip-in.  I had the lower RPM limit set above idle.  So, I didn't expect it to help.  I'll lower the limit and try again tomorrow.