2018 Yaris SE 5MT - T-Sport w/Valvematic!

[atomic_hoji]

So, no such luck on the AFR sensor. Swapped the Yaris' 1NZ sensor in and it didn't change the behaviour - now, the Yaris does use a different part number, but same electrical checks, 4-wire, etc.. and the car ran the same using it. I cleaned the 2ZR sensor by soaking it in gas for several hours and wiping clean - it was pretty clean when I pulled it anyway, but I thought while it was out I'd do it for good measure.

What I did find after I swapped the 1NZ AFR sensor is that when I went to clear the codes there is now a MAF code as well for 'MAF sensor circuit out of expected range' or similar; I'll have to check the OBD2 code, but I think it's P0101. This is new since installing the FPC ECU.

I did also find that the LTFT is better than it was before. The test drive I did after installing the FPC ECU sets the LTFT at -27% (this was before playing with the AFR sensors at all, but after installing FPC ECU) instead of the almost -40% worst case that I had seen prior; loaded the old data and it was fugly, lol. So I think the FPC ECU has helped, but then it's hard to say given there's clearly some other problem.

In a quick read on the P0101 code, apparently the MAF can get tripped up reporting air flow if the signal is noisy from nearby, high current wires. Since I've checked and double-checked the wiring supplying the MAF, I tried a shielding wire quickly - a grounded wire wrapped around - with no change. But, the MAF is basically snuggy-bunny with the main ECM, so going to have to try to rig up a test where I can move the ECM well away from the MAF and see if that helps. The other thing is the OBD2 code does point to a MAF problem, which I boggles me because it's a brand new MAF and electrically checks out when doing the troubleshooting checks. Thinking that maybe mixing the xD 2ZR-FE intake with a 2ZR-FAE iM MAF could cause an issue?! If the calibration assumes a larger intake diameter, so it's reporting X g/s air flow, but in reality with the smaller intake only X-- air is getting in, so it runs rich and the ECM adjusts ST/LTFTs to accommodate ...? Also going to look at the injectors as a last check - they're pink, like they're supposed to be, but who knows, maybe the iM owner had bigger injectors installed?! I can't read the injector numbers while they're in place, so I figure as a last resort I'll confirm the numbers and make sure they match the model injectors.

So more troubleshooting to do.. Generally it drives ok. Misbehaves some at idle and is rough when shutdown; like shutting a diesel off, lol. Since installing the FPC ECU I have found it's touchy when dropping throttle from accelerating; e.g. pulling into traffic and accelerating up to speed quickly, then shifting and letting off the throttle to cruise the revs 'wobble' and rock the engine around on the mounts.. like stabbing at the throttle. Not sure if the FPC ECU change is related or if it's whatever else is causing the fuel issues worsening.

I feel like when I figure this out the AH-HA moment I will feel both relieved and like a dumb-ass - it feels like it's going to be one of those simple things..

-- Adam