JZS161 Single Turbo Problem

[carnetics]

Hi guys

First post here. Bought the car off a member on here recently. Need some help to diagnose an issue before a retune at ST Hitec (Mechanic adjusted TPS and Soichi wasn't happy recommended a retune)

This is the problem I have I hope it's clear

When the car gets hot after 1 hour of driving, the AFRs when not moving with foot on the brake in drive starts to climb into the lean range. It Starts to run rough, AFR can reach up to 18-19 and idle drop to 400. If I shift to neutral it corrects itself but when I shift back to drive it drops Rpm and can also stall. Once I get moving its fine. O

Only happens when car gets hot after about 40 mins of normal use.

All temps are within normal limits. No codes. New coil packs and plugs. Will be getting a new radiator (current Mishimoto one is leaking) and also replacing the O2 sensor for the Innovate LC2 that the HKS FCON ecu uses to run closed loop and also the first thermostat.

I'm trying to get the Mechanic to test for a vacuum leak as well but he doesn't seem too interested in doing that.

Anyone have any ideas as to what else I should be looking at? Fuel pump is new, no issues when cruising but in heavy traffic start stop it does this once the car gets properly hot. It's doing my head in.

Any and all feedback more than welcome.

[BlakeNZ]

did you manage to get this sorted?
i believe it has to do with the tune, especially to do with the air intake fuel map correction. These JZ motors are massive heat sinks, and once that large alloy inlet manifold is heat soaked , it can take AGES to disippate the heat.