Sudden lean condition after warming up

[maKe]

Good morning,

I've got quite unusual problem that I can't seem to figure out yet on my own. After cold start I can steadily idle the car, and after 5 mins or so, it's pretty rock solid lambda 1 idle between 850-950 rpm's. After coolant temps achieve +80c (81-84c) and it's idling without any issues for few minutes, then the lambda starts to read 1.3-1.5 and the car starts to sound like it's missing one cylinder and hesitates really badly when inputting throttle.

What is also very confusing is my wideband 0-5v input to the EMU. I have AEM X-series LSU 4.9 wideband meter/controller connected to ecu input. 0-5v signal positive to emu input and negative to emu sensor ground. Wideband controller itself is to the chassis ground. I had to calibrate 0v to approx 1.25 afr and 5v to 15.2 afr to even get emu read the same lambda number what the aem meter is showing.

It's a jzx100 chaser with 1jz-gte vvti engine that I've built and installed emu in it. E85 fuel, 1300cc ev14 @ 4bar fp, vag coils, 272 bc cams, custom intake manifold with 90mm tb, no IACV valve etc. Currently just running base map with working idle and low load vacuum fuel table and cranking tables that I´ve made to just move the car around. Ignition is spot on when checked with timing lamp.

Heres the tune and log from yesterday. Hope you guys can help.

[maKe]

Log and tune:

[Paulo11]

I think, you just must tune your VE map properly.

[maKe]

I think, you just must tune your VE map properly.

That would be true usually, but never saw such drastic change in afr's by just idling for a while. Well, installed new plugs and changed the wiring a bit as I had flex fuel connected to sensor ground and not to ecu/chassis ground. +12v feed to to the emu straight from battery via relay so the voltage reads correctly now (had approx 0.5v voltage difference before when measured from the battery and compared with emu readings).

Then made sure that I had all enrichments and corrections switched off after coolant temps approached ~80c and guess what, I couldn't replicate the situation anymore.

Maybe it had something to do with IAT temps, IAT placement and charge temp approximation map when using advanced lambda strategy but all seems to be good now. Time to fabricate charge piping, exhaust, breather kit and power steering reservoir and hit the dyno then.