I have been tinkering with tuning for a while with Neptune with great success. I'm getting to a pretty deep understanding of all the features and settings of the tuning program.

I have this weird issue I can't seem to figure what is going on. When I let off the gas fast, and the throttle plate shuts very quickly. While watching my wideband, the A/F's spike way rich for a sec after throttle close, then go lean like it should for proper deccel fueling.

Example: like while on the freeway, cruising at around 14.5, snap the throttle closed, wideband reads in the 12's or even 11's sometimes, holds rich for a sec, then goes lean.

No matter how much I adjust the fuel map cells in the area below the currently logged cell, this happens. I can put them at zero and the fuel still spikes rich. I have played with Tip-In, and have this running wonderfully. I have recalibrated my wideband many times, and it works great. I strongly believe that the wideband is reading correctly, and is not the culprit. Base fuel pressure is around 55psi, AEM FPR, stock lines. I'm running Bosch 1000cc EV14 injectors (High Impedance). VictorX mani, skunk2 65mm TB. Fuel pumps are in-tank Walbro, and inline Bosch 044.

Could this be the way I re-installed the OEM TPS on the VictorX manifold? Too much fuel pressure? Fuel pressure spike on throttle close? Is there a "Tip-Out" setting that anyone has heard of? (Haha I doubt it). Any thoughts on what this is? It is bugging the crud out of me.

 

Yes, there is no tip-out setting available. That's what occurs when you go to no load quickly.

 

Its normal... eCtune has a setting for tip-out, but Ive not had much success with it. Doesnt seem to make much of a difference. Im sitting at "-10" tip-out right now & still have a slight rich spike in between shifts and immediately upon decel. I just threw -10 at it to see whta it would do. I wouldnt worry about it much unless it becomes a driveability issue.