1UZ-FE / SAFC Neo weird tuning problem?

[Sciflyer]

Car is a 1994 Soarer V8, headers, exhaust & intake, otherwise stock

Had a strange problem while dyno tuning at WOT, AFRs could be adjusted up to around 4500rpm, but no matter what was tried the AFRs after ~4500rpm would not change at all :-/

SAFC was reset, wiring checked etc, nothing worked... result is i got a 20hp increase in the midrange where it worked, but then it just drops back to sub 11:1 AFRs in the upper rpm and power here of course is unchanged....

Could the ECU somehow be overriding or ignoring the SAFC/sensor input?

Doesnt make sense to me, and the dyno guy had never seen it before either

I'll upload the dyno printout later which makes it obvious but would be interested to hear any theories?

[CrUZida]

Does the problem happen at xx rpm or at xx throttle position (which just happens to line up with 4500rpm) ?

Because I know 1UZ's do something wierd at about 70% throttle (random guess)

[Sciflyer]

I would guess that 100% throttle would be do-able at that rpm without kickdown screwing up the dyno results.

Apparently the stock ECU wont go into open loop at anything less than 100% throttle? and its pointless trying to make corrections in closed loop

Anyway here are the printouts, firstly a stock one from XSpeed a while back



and the results from Hyperdrive while trying to tune the SAFC, base run in blue, the best result we could get in green



You can see the attempt to get around 13:1 from about 3500rpm on, then at 4500 nothing would stop it from dropping back down to teh awesome stock 10.5:1

A couple of other things ive noticed-

*Hyperdrive dyno intake temp seems very high, rpm scale looks wrong (redline is ~6200rpm not the 5700 shown in the printout...
*Cant explain that persistant dip in the high rpm...