Okay, so I've already searched for answers on here and have read a few people having similar issues, but no real answers. Most of the people who experienced problems like this had aftermarket camshafts and just needed to pull timing at lower Cylinder airmass/rpm. For me, I would think my stock Z06 tune should run with zero drive-ability issues. I tried this regardless, with no luck.
Vehicle details:
2007 Z06 with 15k miles
-Halltech MF103 intake
-Ported stock TB (by Tony Mamo)
-Intake shroud cut for more air-flow
-160* T-stat
-B&B fusion cat-back
-TR55 plugs .040" gap
I bought the car with 12.4K miles on a stock tune with zero issues running these mods
-Halltech MF103
-B&B fusion cat-back
-Then I added the TR55 plugs, still no problems.
Again, the main issue is large drops in timing while cruising at low rpm and low cylinder airmass. The spikes usually happen between 21-30% TPS (NOT accelerating) and of course cause severe bucking . I believe I can't get the LTFT's perfect because the timing is constantly dropping and raising back to normal, too. Now, anytime I accelerate, the car runs very smooth. The harder I accelerate, the more spot on the tune seems to be.
*Another note* I went to "The Tuning School" last November, so I got one year of free tech support. When I called them, sent a tune/datalog, they said they've only seen this a few times and each time there was either a ground problem with the ECM or the ECM was defective in some way.
IMO, I don't think this is the case, for one main reason. As a test, I turned off virtual VE, fuel enrichment, COT, DOD, AND disabled MAF High. After doing this, I was able to completely eliminate all the surging and bucking. That being said, the LTFT's would never dial in very well and as soon as I turned MAF High back on, all the surging came back and got worse. I realize that was not a fix, nor the way you should do things, but it did get rid off all the surging, which is interesting. So, if you can get rid of the surging that way, how could there be a mechanical problem with the ECM ground or overall ECM??
I should also note that I originally planned to tune this car MAF only and disable VE (I'm not familiar with Bluecat, but plan to be in the future). I originally had it disabled, then enabled it back on to see if this would help the issue, but saw no change.
Any help would be much appreciated! I'm going to post my datalogs and tunes in a second. I just didn't want to write this on my tiny netbook...