Inaccurate Innovate wideband?

[idt512]

My Innovate MTX-L wideband doesnt seem to be in sync with its own analog wideband output. Ive dialed in my AFRs to 11.0 on the gauge but the analog output reads 1.16V, and according to the formula (10 + Vx2 = AFR) equates to 12.32 AFR. At this setting i get knock in several areas and think i can actually hear the knock. Back when i was tuning with a narrowband I tuned for .94-.96V I had it running nicely with no knock and a steady ramp on the timing advance, but after installing the wideband and without touching any settings i found that it was between 10.0 - 10.3 (according to the gauge) and I aimed for 11.0 right off the bat. So today i went back to 10.3 AFR and the knocking is gone and timing advance is nice again. Something tells me my analog output is correct and the gauge is wrong because of the knocking im experiencing. Anyone else experience incorrect readings on their Innovate wideband?

Ive been trying to tune it out for the past 3 weeks, in doing so ive probably put about 20 runs close to redline in those conditions. I wonder what kind of damage has been done to my engine if i was truly at 12.3 AFRs at 17psi. Everything still feels normal, but it bothers me because its a newly rebuilt engine just last year.

Oh, and yes i did the free air calibration during installation.

 

[gofer]

The analog yellow output 1 on the MTX-L (0v-5v) is set to a 0v = 7.35:1 and 5v = 22.39:1 AFR with a formula... AFR = (V*3.008) + 7.35.

That being said...

AFR = (1.16 x 3.008) + 7.35
AFR = 3.48928 + 7.35
AFR = 10.83928:1

 

[idt512]

Ive never seen that formula, do different manufacturers have their own formulas? Ive read several threads now with the (V x 2) +10 and one in particular was discussing an Innovate wideband so that is what i followed.

Given that new formula, i guess my car just likes it at 10.3 then

 

[gofer]

Ive never seen that formula, do different manufacturers have their own formulas? Ive read several threads now with the (V x 2) +10 and one in particular was discussing an Innovate wideband so that is what i followed.

Given that new formula, i guess my car just likes it at 10.3 then

That's because you're reading threads full of misinformation and generalized formula's.

Yes, each manufacture has their own AFR and voltage range for their particular wideband sensors. That formula I posted above is Innovate's formula specific to their line of wideband gauges, I run a MTX-L myself.

...and the reason why you're seeing a 1.16v output but showing a 11:1 AFR on the gauge is because that formula doesn't take into account any ground offset, which can also change your voltage output being logged. If you've done the free air calibration on the sensor within the last few months your gauge is accurate and based off of the voltage output you're logging you've got a small ground offset that's skewing the voltage a bit from the actual AFR reading. Say your true output voltage is 1.22v but you're logging a 1.16v reading, only a 0.06v difference which seems small but...

AFR = (1.22v x 3.008) + 7.35
AFR = 3.66976 + 7.35
AFR = 11.01:1

Odds are you've got a bit of a ground offset skewing the output voltage too.

 

[idt512]

Well I feel much better knowing it wasnt actually running leaner than 12.0 AFRs. When I said 11.0 its actually bouncing around 10.9 10.8 so the voltage reference is probably correct... One thing i should note is my ground is connected to the cigarette lighter ground because my +12V was initially tapped to the cig lighter power, but I have since moved my +12V to the fuel pump relay because I wanted the wideband to only power up when the engine is running, and not when the key is on ACC. Reason being, I go to work 10-15 mins early and I sit in the car with the radio on and I prefer to not have the wideband powered up.