What is your problem exactly when tuning with the neo ?
You have to keep in mind that you're tuning by modifying the MAF signal, with the neo. That signal is a 0 to 5V, it gives the "load" information to the ECU. Fuel injection and ignition are directly linked to that signal. If you modify it, you will get a different AFR. So it works - or it's not wired correctly.
Then, you have to understand the limits of that system :
- If you bring the signal to 0 or 5V, the ECU will not like it,
- At a certain value, the MAF gets "pegged". The ECU is not programmed to handle that value and beyond, it will either cut fuel or go back in closed loop mode, bringing you to 14.7 AFR. Generally that value is around 4.7 V on our tibs. So don't be surprised if, by increasing the MAF voltage at high rpms, you get very lean AFR. You may have pegged the MAF. At high rpms and high load, if you have to increase that value beyond 4.7V because your AFR is a bit too lean, then stop and buy bigger injectors. Your MAF must never go beyond that 4,7V. You'll certainly need a MAF clamp, or fuel cut defender (cheap on ebay). Those boxes will keep your max MAF value at 4,7V when it wants to go higher.
- By modifying that signal, you are also modifying ignition. At WOT, the ECU will retard ignition when load is incresing. If you reduce that load signal, you stay with a high ignition advance. Good for hp, bad for reliability. Very bad with boost.
With the ZT2, you have an excellent datalogger, with user inputs. Considering you're tuning by modifying the MAF signal, the best thing to do would be to tap your ZT2's user input in the MAF wire. Thus you'll be able to monitor and log your MAF signal.