After roughly a year on and off cruising the nefmoto boards, reading and rereading ∞ the wiki, exploring and analyzing the tuned files others have made, creating comparisons and tables depicting which parameters individuals alter when tuning so that I could gain a sense of whats absolutely necessary for relatively modest gains and decipher what parameters are likely based more so on tuner preference and/or properly coding out various unwanted components (SAI, n249, CAT, post-CAT o2...). I finally reached a point where I felt comfortable enough to quit starting with already tuned files as "base tunes" of some sorts and actually going hands off and giving it a shot without the training wheels... So as I was saying, I just recently completed a file that I remapped myself with extremely minimal referral to the wiki or any tuning pdf... I am very pleased with the overall power output of the engine as well as the throttle response as far as low RPMs are concerned. Due to the fact I made this tune on my own without any guidance or map/table references, regardless of my confidence in my understanding and grasp on things at this point, I think it is a good idea to remain modest and not get overwhelmed with confidence only to result in irreversible damage to various components due to who knows what... I have yet to encounter a DTC and I've driven the car for roughly 40 minutes total in about 4 different short drives while recording logs. below is a graph taken from a short drive earlier today. Btw, Just so you know. I didn't touch on fuel much. I didn't feel that the modifications I was making would require alterations made to parameters such as kflbts, but next time I open the tune up thats where I'll likely be going next along with other minor adjustments in their respected parameters..

So here is my question.
First off, I've been logging over the past 48 hours whenever I have a chance... Take a look at a graph from the most recent log:


When me and my fiance were reviewing the log I grew concerned due to the dramatic spikes where the A/F ratio becomes extremely lean for a brief moment... Way outside stoichiometric / ideal fueling for optimal torque (barely barely BARELY on the rich side... ya know?)

Anyways my fiance quickly pointed out that the spikes occur during deceleration after longer periods of increased speed (more so in regards to gears past 1st or 2nd...) I am not having any luck finding any info from multiple google searches so I am turning to anyone here for some assistance.

Thanks in advance if anyone can assist. I'll post log when I get home.
evaluate when driving and now even more so

So I shouldn't be too concerned by those lean spikes? I just want to ensure that I'm not going to break anything pushing it to redline. I thought maybe someone could take a look at the log I took and see if anything stands out that should be addressed before pushing things any further. Regardless, I'm just going to go with your recommendation and log that 3rd gear pull.

What parameters should be logged during this session?

By the way, Vehicle:
Make/Model: 2001 MKIV Jetta, Engine: 1.8L 20V, Turbo: k03s, Engine Code: AWW, ECU: 06A906032DL

Right now I'm logging:
"IgnitionRetardCyl1","IgnitionRetardCyl4","IgnitionRetardCyl2","IgnitionRetardCyl3","LambdaControl","AdaptationPartial",
"CountMisfireTotal","LambdaPartProtection","TargetAFRDriverRequest","AirFuelRatioDesired","AirFuelRatioCurrent","BoostCorrectFactorPID-I
Range1","ChargeLimitPID-I","WastegateDutyCycle","EngineLossTorque","RequestedTorqueTractionControl","EngineSpeed","BoostPressure-
Desired","BaroPressure","BoostPressureActual","AdaptationIdle","EngineLoad","EngineLoadCorrected","EngineLoadSpecified","EngineLoad-
Requested","EGTModelBeforeCat","IntakeAirTemperature","EGTSensorBank2","EGTSensor","FuelInjectorOnTime","VehicleSpeed","ThrottlePlate-Angle","AvgIgnitionRetardKnockControl","AccelPedalPosition","IgnitionTimingAngleOverall","CondOverboostActive","CondFuelCutoff"

I know the wiki mentions the parameters to log that will help diagnose and troubleshoot exact issues, but I'm not experiencing any noticeable issues so far while driving. What I'm saying is, there is nothing occurring while driving that makes me worried that something wasn't tuned properly (you know, like the car almost dying while idling, experiencing rough driving conditions, check engine lights...) none of that. With that being said, I completely grasp the concept of the phrase "dial in your fuel"... I've always taken that term very seriously since I got into this stuff... I understand the consequences that come with neglecting to ensure your fueling is correct before pushing the limits of your tune. So the first order of business for me, was to begin logging my file, paying extremely close attention to AFR and fuel related parameters. When I began to see these spikes out of the corner of my eye on the laptop I grew concerned. I innitially thought the spikes were fuel being cut... And I just went back to ecu_xplot to take a look at "CondFuelCutoff" and wouldn't you know it! look at the red parts of the lower end along the graph:



So now that I have concluded that the lean spikes in my log regarding "CurrentAirFuelRatio" ARE in fact some type of bi-product of fuel being cut due to "CondFuelCutoff" kicking in for a breif moment... But this confuses me. (If someone could chime in, I would really appreciate it a lot!) I'm curious if CondFuelCutoff (fuel cut) is a common regularly occurring command that takes place even in cars running stock files? I ran a lot of logs, for months before actually flashing any tuned files but sadly, after looking back just a moment ago, "CondFuelCutoff" was never selected to be logged  thats on me... Anyways I thought "CondFuelCutoff" is a command automatically ran by the ECU when the pre-cat sensor detects the AFR is too rich and therefore, the ECU will cut fuel briefly to try and reestablish a stoichiometric AFR... Now from what I personally see in the graph is that my AFR doesn't seem to get dramatically rich enough to justify cutting off fuel for any period of time? Maybe I'm missing something...

BUUUUUT, I did however buy some new BKR7E NGK plugs from autozone when I was up there and I'm running hitachi coils with a little under 30,000 miles. So I think once I put these new NGK plugs in with proper gapping (because when I put in the set of BKR7Es that I'm running now, I wasn't tuned. So I gapped them like 0.01 towards recommended tuned gap specs from stock specs. So maybe my plugs aren't able to keep up with the demands of my tune? IDK lol I need a little help :/

These are my ECU_xplot PID settings for my specific car, are my settings correct? innitially ecu_xplot seemed to have come stock, setup for a twin turbo with much larger injectors than my single k03s and 317cc injectors.



Thanks in advance again. Also, if you or anyone else could tell me what you guys think would be some essential logging parameters I'm all ears. Or if my list is on the right track, maybe it would be a better idea to just give me a list of all the dead weight in my current logging parameters. I'm going to go record the 3rd gear pull @nyet said I should do after I finish getting these new plugs put in. So I'll be back in a couple hours.
Thanks!

My list:

http://files.s4wiki.com/ME7L-ecu/8D0907551M-typical.cfg

This is for a narrow band car, so it is lacking actual AFR.

Thank you nyet 

Why would there be spark during fuel cut? What's the purpose?
You're just pumping air through the engine - what would be the "air-to-fuel" ratio with fuel being close to zero?

Besides, in low load areas this is pretty much irrelevant. Stop going "woo, it's lean, it's gonna grenade!", and start actually thinking about what and why happens in the engine. The main "dangerous" moment where you should avoid going lean - is WOT pull from boost onset to redline.

EDIT: And even if there was spark during fuel cut - what would burn without actual fuel, huh?
EDIT2: Sorry for sounding a bit annoyed, but seriously - your questions show either complete lack of understanding how the engine works or inability to hear what you're being told. If it's the former, - well, it's fine to learn, but please do some basic reading on principles of ICE operation before even considering tuning it yourself.