Digi! i thought you resolved your issue with a new brake switch?
That is exactly what it feels like and what it looks like. i have a datalog which managed to capture a normal drive and the lead up to a lag episode, and the aftermath which was full on lag.
I have never got any CEL or DTC either. Which suggests the ECU might be at fault because anything which strays away from its command and expected response/result should cough up a DTC. But for it not to notice, a sensor must be reporting the malfunction as normal. I guess if overheating the oil can cause a limp mode effect without DTC, there might be other failsafe/protection modes which dont trigger a DTC. I have never experienced the full on oil temp related limp mode to be able to provide any insight on how the ECU restricts RPM and performance.
Anyway, back to your question. When it happens, the engine is literally choked and gasping for air. According to my logs, it recognises that the gas pedal is floored but the throttle plates are being restricted. It definitely feels like a commanded choking restriction rather than a dodgy TPS reading. What happens to me is the throttle position seems to be limited to max 20 degrees opening up til about 3500-4000rpm upwards, at which the car screams and takes off. But the throttle plate doesnt get to 20 degrees quickly. Just like you said, it takes an eternity. So when the lag hits, i really struggle to get the car off the line. Even a shitbox can accelerate away with minimal effort. Taking off uphill or with a full load requires some careful riding of the clutch and building momentum by holding the revs at 2200rpm then riding the clutch. by doing this, the throttle opens appropriately to match the revs. If this isnt done then the throttle position stays at whatever it is at idle, eventually opening more as the rpm eventually increases.
Merging into traffic, overtaking or even just turning at intersections can be damn dangerous, because you press the gas pedal like you normally do in the same circumstances and nothing happens. You become a sitting duck for the few seconds before you get thrown back when the engine screams to life.
When it happens, i also notice the VVT system change. The change in VVT and throttle plate behaviour are the only things that stand out consistently in all my logs taken during the lag episodes. Unfortunately, i havent been able to fully explore the potential VVT and VVEL system fault path because of lack of support. I really need some datalogs from other vehicles to compare with mine. The reason is because when the car behaves normally, the VVT system does not behave like it does in most other cars - Toyotas, or even in the R35 which has CVTCS also. So currently i have concluded that due to VVEL, VVT behaviour on our cars is different to that of non VVEL engines. Without other people's logs, i cannot go further with this avenue.
Without my Scangauge, i would've not been able to pick up instantly on the throttle restriction during these lag episodes.
I hope that helps in some way. Another thing id like to mention is that i took it to the dealer and they blamed my G3 intakes. I scoffed at them and i have not removed any of my mods. I have not de-modded because the car was running fine for a while with all these mods. However, after demonstrating the lag to the tech he disgruntledly took the car into the workshop and came back 5mins later to hand the car back to me. The issue didnt come back for about 2 weeks. You can imagine the heartbreak when it happened again...
Ever since then, i've been taking a few punts, chucked some money into replacing sensors without success. The one thing that i have noticed is that after performing what i have grown to call the trifecta of relearns (gas pedal rest position, throttle body rest position and idle air volume), the issue doesnt come back for about 1.5 weeks. For me, that's about a tank and a bit. I discovered this after i replaced the gas pedal and also after trying to resolving my sagging idle. I did the trifecta again after cleaning my throttle bodies last weekend so we'll see how it goes. Im getting tired of holding my breath
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