muthagoose

I’ve been tuning my 01VVT car with @18psi remotely here for the last month or two. Car is setup great on pump fuel (its been a blast tuning with 18psi), still n/a right now working on dialing in the tune on gas/flex before installing my turbo setup. Currently we are working on the E85 tune and had a weird AFR issue come up during WOT 3rd gear pulls. I was hoping to see if anyone had any guesses as to what’s going on other than what Vlad and I have checked so far? This just popped up out of nowhere after about 18 iterations of tune changes. Throwing this thread in Megasquirt tuning section as I think it’s most relevant to.

Info on the car- 01 VVT engine, MS3 PNP Pro, Innovate MTX-L Plus AFR gauge/ Bosch 17025 o2 sensor, gm flex sensor, DW200 pump, id1050x's. etc..

I’ve had the o2 sensor that came with the MTX-L plus die out on me about 3 months into use, on my replacement bosch o2 right now. The AFR on the gauge and the AFR in TS both show the wonky fluctuations. Fluctuations only happen at WOT and around 4k rpms (see attached). I’ve also just started seeing the AFR flat line or get stuck during this spot of RPM's. O2 is installed in the upstream bung on stuck header.

What we have checked:

• No exhaust leak
• Wiring between O2 and Gauge to ECU is fine. Signal wire from Gauge is hooked to stock AFR line at back of head. Gauge is grounded at ECU. I have a new O2 sensor I’m going to install tonight but don’t have hope.
• AFR's are fine everywhere else, also don’t feel the AFR fluctuation at WOT, so leads us to believe its a false reading.
• I do have a coil pack plug that is missing the detent that allows the wiring to "Click" on. Have this secured with ziptie/wire for now. Original thought was maybe at 4k the vibration is making this coil pack lose connection? But then again I don’t feel any loss of power during this situation. Pulse widths are smooth, duty cycles are smooth, VE is smooth, and timing is smooth.

I’d appreciate the remarks, I really wanted to get this out there on the threads in case anyone runs into this in the future. Hopefully we can solve this annoying issue soon.

18psi

iTrader: (76)

Notice how it swings completely lean after about 6k? If the car was actually that lean it would not stay on at all. 22.5AFR means zero fuel, 100% impossible to accelerate, and yet engine speed keeps going up like nothing happened. IDC and PW are also stable. Nothing is wrong.

Hence why I think this is some sort of glitch or electrical issue, perhaps wonky wideband.

*EDIT: looks like that's exactly what it was, wonky wideband

muthagoose

Solved,

Its apparent that the Bosch 17025 O2 sensors are not a fan of launch control, or any O2 sensor for that matter.

The O2 sensor was just bad, replaced it with a new one off of amazon and everything is fine again.