the tuner added timing to try get rid of the dip but it had no effect. It was done as a diagnostic measure to try eliminate possible reasons for the dip. if even a really advanced spark doesnt make a change, then the problem must be mechanical right?
the z32 afm has not been tested in another car, but it has not shown any abnormal behavior. it has fine resolution up to 160kw initially, and then again up to 200kw on the second tune (around 3v on the first power level, and 3.4v on the second). I would expect if it was the afm, we would be seeing some weird outputs and perhaps even a flow ceiling, but the second tune with an increase in power and hence flow resolution sort of rules that out.. but if that power/torque curve could be a result of a faulty meter, then I can definitely add that to the list of things to diagnose.
no fault codes were found, and my tuner removed all safeguards temporarily to make sure the computer wasnt trying to safemode or anything, for example, fault knock sensors can cause the ecu to pull lots of timing to protect the engine when there is nothing wrong, so we pulled that to be sure it wasnt.
essentially my tuner has eliminated all possible electronic causes out, hes increased the output of the ignition system, there is no missfire and there is plenty of fuel.
current tune now has no ignition dumping to try quick fix the dip, holds a safe AFR throughout the range, so its up to me to try find the cause. if I can fix it, the ecu should be able to relatively safely extrapolate fuel and timing to keep it safe, but i will definitely put it back on the dyno