ngk afx error

[backchannel]

My afx reads lower than scanner using the pre-set pid. What would I change in a custom pid. Pre-set is V/0.7142+9. Scanner reads about 0.3 higher.
thanks for any help

found it.

[EC_Tune]

And it was???....

[thesubfloor]

My afx reads lower than scanner using the pre-set pid. What would I change in a custom pid. Pre-set is V/0.7142+9. Scanner reads about 0.3 higher.
thanks for any help

found it.

Try using Volts/0.713 + 9.11.

My HPT matches almost exactly with the NGK AFR meter using those values.

Christopher

[1.8t]

I don't know about you guys, but I have to modify my equation every single time I go to log my car to make it match from my HPT readout to the NGK display. I have a very accurate way of doing this and and I usually have to add or subtract somewhere between .02 to .06 from my previous 9.XX value.

Is this normal?

[backchannel]

Well, this is quite annoying. The error is small but changing. I'd like to tune from logging but can't tell if it is the wideband or the scanner that miscalculates from the voltage. Playing with offsets and ramp rates doesn't seem to make the readings equal from 9 to 16:1 consistantly. Any guess which display is reading the o2 better?

[lito]

When in doubt, always take the leaner one. Better safe than sorry.

[Trannyman95]

I spent hours dialing in my AFX when I first got it and that was about a year and a half ago and it is has been pretty much spot on ever since. My formula that I came up with is V/.6901 + 9 . It took a lot of time getting the skew from 9 and up to stay consistant and it really seemed like system voltage played a role also and the car has to be running for it to read the same. Key on engine off with lower vehicle voltage and the two are off a few tenths. I have not had a single problem with this WB and works great as a portable type unit for tuning different cars.

[backchannel]

I spent hours dialing in my AFX when I first got it and that was about a year and a half ago and it is has been pretty much spot on ever since. My formula that I came up with is V/.6901 + 9 . It took a lot of time getting the skew from 9 and up to stay consistant and it really seemed like system voltage played a role also and the car has to be running for it to read the same. Key on engine off with lower vehicle voltage and the two are off a few tenths. I have not had a single problem with this WB and works great as a portable type unit for tuning different cars.

that sounds good. I was doing it with engine off , then running without thinking about voltage affect.

[1.8t]

I have mine powered and grounded directly from a battery and use a switch to turn the w/b on/off. I still have to modify the equation ever so slightly. What I have figured out is that matching the w/b to the HPT display at, lets say 12.5 a/f, will require a different equation than matching the two at 14.5 a/f. Apparently the equation I am using is not linear. Depending on what a/f I use to match the two, the a/f's at the opposite end of the spectrum will be ~.06 or so off. Thats not really a big deal, but it was driving me insane trying to understand the variability.

[5_Liter_Eater]

I spent hours dialing in my AFX when I first got it and that was about a year and a half ago and it is has been pretty much spot on ever since. My formula that I came up with is V/.6901 + 9 . It took a lot of time getting the skew from 9 and up to stay consistant and it really seemed like system voltage played a role also and the car has to be running for it to read the same. Key on engine off with lower vehicle voltage and the two are off a few tenths.

Thanks for that tip. I always calibrated my PID by turning on the key with the motor off and watching the gauge slowly go lean and alter my equation based off of that. What I realized after reading this was that with the motor on and 2V more voltage it's different. So I got that corrected by taking a bunch of digi pics of the WB gauge and HPT to see where they were in relation to each other in steady state ~14.7. I found that they were ~.3 different (HPT being leaner) But now I'm wondering if my equation is not so linear either. My WOT target AFR is 11.5:1. My WB gauge is pegged in the low 10's but my AFR error doesn't seem to be that great. I don't have time to compare the two when I'm doing a WOT run, 600 RWHP takes some concentration but I don't think they're the same at that low of an AFR.

I'm starting to see the draw of being able to use the WB's serial output but then again there would be no way to pipe that into HPT via the AC input.