AFX Step-Saver Idea

Thinking out of the box here......literally.

I think I have been doing what everybody else generally does and that is to free air calibrate the AFX with the black knob and then next match up hp tuners via the offset voltage formula second.

But......

I am totally reliant on the output wires and never use the AFX box face readings. In reality I only care that the sensor and HPT are in sync. Do I really need to waste a good offset voltage adjustment knob to obtain a perfectly calibrated in between box reading I only look at long enough to say okay before I go spend time "fixing" the real reading I use.

So......

When I am heating up the sensor in free air, why not just use the AFX black knob to calibrate the voltage to read 16 AFR or 5 volts in HP Tuners and move on?

Free air calibration and the analog output aren't completely tied together.

You can check your power supply cleanliness during warmup because the box will spit out stoich (3.96v) for a short period.

After some wiki-oogle I see how it doesn't work the way I was assuming. Thanks for the reply.

Like DSteck said on the warmup the AFX will output a stoich signal from the 15 to 5 second countdown. From 5 on down to 0 it will output the lowest possible reading which in the AFX case is 0.6177 lambda or 9.00afr.

Every car's charging and electrical system has a little bit of noise in it and will throw the numbers off very slightly, normally its not enough to cause issues however I always calibrate my scanner to read correctly before I start tuning a car.

Thanks for the reply.

The first time I ever used a wideband I cut off the pigtail of a narrowband and made a plug n play for a PLX wideband simulating a narrowband in the OE bung. That setup turned out to be maintenance free and my first WB benchmark. A couple of years later with an engine and transmission swap, I bought an AFX with NTK sensor and welded in a separate bung. I ran the AFX two ground wires to the battery and then the AFX output ground to the HPT EIO. I ran an extra ground to the battery from the other HPT EIO ground slot. Added a jumper to a separate EIO slot from AFX signal EIO slot for reading voltage. Since that time like most people I have been calibrating plus dumping a csv file for voltage to take an average of the stoich readings since. I agree I had a wishful thinking mistake about the calibration knob and resistor wire to sensor, etc. which DSteck pointed out.

On another note I may have inadvertently stumbled onto another way to reduce my startup time, for my setup anyway. Three days ago, I added a jumper between the HPT EIO ground terminals to complete a gauge grounding requirement when I am not using the EIO plugged into HPT interface box. An unexpected side benefit came in checking my csv stoich voltage average the last three days, my voltage difference has been no worse than .002 where it typically was .03 before. If I pull the jumper it goes back to .03 territory. If I can consistently get within .002 by this added ground jumper then that's close enough for what I am doing and I won't worry about offset adjustments.

Yeah I normally just tune on the dyno and I use separate power to energize my wideband. I keep a spare 12v car battery charged and power my AFX off of that. It is noise free using the external battery!