Tuning help! - HEGO 2 @ 64 volts!!!

[VenomousISA]

Hello Everyone,

In need of dire help.

2003 Ford Mustang GT
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5.4 4V motor (Lincoln Navigator)

W/ original 03' GT PCM - modified to new engine layout
W/ twEECer RT device using CalEdit & CalCon for tuning (Mike Glover - STKR)
(general mods: 5-Speed TR-3650, Velocity Stacked Intake Manifold (5.0 Coyote) w/ MMR Intake Adaptor Plates for 5.0 Coyote intakes, 90mm Accufab Throttle Body w/ custom 4" K&N intake, Injectors #60lb/h Siemens Dek High Impedance [60lb/h @ 43.5psi and up to 100lb/hr @ 80psi], DeatschWerks DW300m Fuel Pump - 340LPH @ 40psi, Zeitronix ZT-3 AFR Controller / Bosch Wide Band (standalone), DataQ-145 (not hooked up yet), EGR Deleted, ### MAF)
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Was in the process of tuning session. On my 3rd tuning session over a 1 month period. After doing a 5 minute street drive and a 5 minute freeway drive, did a couple WOT's. Came back from my tuning drive, saved my datalog, then it was observed that HEGO2 pegged at 64 VOLTS [RICH] and stayed there ending our tuning session.

The Tuner, Mike Glover said that the prior tuning sessions showed this HEGO2 as "weak" then got better with some tweaking. But that it has progressively gotten worse until it became "dead" according to the readings on CalCon V1.35.

I attempted to swap out Driverside upstream narrowband 02 sensor with a new one, but no changes.

What should i check next?

Ideas?

 

[VenomousISA]

any thoughts on this?

 

[Noobz347]

My only thought is that your 64 Volt reading is inaccurate.

No idea why

My other thought that the value of "64" is not a voltage reading but something else... Probably LAMBDA

Replace the O2 sensor and try again.

 

[VenomousISA]

Thanks for the reply.

I got wind from a Chicago buddy of mine that he had something of a similar issue, and his signal wire from the 02 sensor was snipped in the middle somewhere within the harness. He said he T-Tapped into the signal wire near the ECU, and ran a new wire towards the 02 sensor and T-Tapped back into it and was able to complete the circuit. I have yet to try that method.

I already attempted to replace HEGO2 02 sensor with a BOSCH, which should be Driverside upstream near the header. But I have the same 64v reading.

 

[VenomousISA]

All thoughts welcomed, your statement about LAMBDA will allow me to at least look down that "keyword" rabbit hole pertaining to such high voltage - lets see what that yields..