# Thread: AEM EGR Wide-band math check

1. ## AEM EGR Wide-band math check

Hello, I am wondering if I could get some help. I set up an AEM wideband through my EGR on the ECU. I am wondering if someone could verify that the calculations are correct.
I attached my Wideband formula and formulations. I also included my graph settings to make sure that they are right.

I have attached some screenshots for reference. Let me know which would work better for my idle tune, the WB ERR graph or the updated graph. I know that if this math is off the entire tune will be off.  Reply With Quote

2. Here is what my AEM x series math looks like:
AFR Sensor user math ([2811.10]*2.3750)+7.3125
AFR Error user math 100*((([2811.10]*2.3750)+7.3125)-)/  Reply With Quote

3. Why multiply and not divide? This is where I got my formula from -> https://www.corvetteforum.com/forums...hp-tuners.html

What makes your formula different and is it more accurate?

Sorry for the questions, I'm new to tuning and want to make sure that I have it correct. One wrong calculation and everything will be off.  Reply With Quote

4. The AEM X-Series (newer style) wideband added the proper math formula into the paper work. That is the formula. It is perfectly accurate with this wideband as it has a calibrated resistor built in, but can be free air calibrated down the line if needed (sensor degredation).

quote from your link:HP Tuner Scanner

• Now that the wiring is done, you need to set it up in HP Tuners. You will need some information on your specific wideband that will be in the widebands paperwork. You will have to set up a formula to change the voltage (0-5v) into your AFR wideband reading. It will look like this:

VOLTS / (VOLTAGE RANGE/DEVICE RANGE) + (MINIMUM VALUE OF DEVICE READING) = AFR

VOLTS = the voltage that the wideband 02 sensor is putting out to the EGR wire

VOLTAGE RANGE = typically 5v (0-5v), some people use the narrowband 02 input (not recommended) which is 1v (0-1v)

DEVICE RANGE = the range your wideband is set to read. If the wideband is set to read from 10 – 20 AFR, then the range will be 10. If set to read from 8 – 22 AFR, the range will be 14, etc.

MINIMUM VALUE OF DEVICE READING = the lowest number that your wideband is set to read. In the above examples, it would be 10 for the first example, and 8 for the second.

I am using a PLX SM-AFR 250 that is set to read AFR from 10-20, so I will use it for my example. The formula will be:

VOLTS / (5/10) + 10 = AFR or,

(VOLTS / .5) + 10 = AFR

• Since HP Tuners Scanner will be using the EGR or AC Pressure switch to get its readings from, we need to add that into the formula. The PID for the EGR on LS1 based cars is PID.2811 (EGR Position). Now the formula reads like this:

([PID.2811]/.5)+10 = AFR

• The formula for the A/C Pressure switch is the same, you will just have to change the PID to PID.7101.

([PID.7101]/.5)+10 = AFR

Your math is /.4+8.5, why did you use that math? What AEM wideband do you have? I have only seen two formulas for aem: ([PID.7101]/.5)+10 = AFR and ([2811.10]*2.3750)+7.3125 second formula is for the xseries  Reply With Quote