HPTuners question

KYWes · Mar 27, 2021

I've created a User Defined math parameter using the Math Parameter Manager tool in VCM Scanner. How do I use it in a Transform of a channel I've created?

This is the function I created:

I'm trying to create a channel using my MPVI2 w/Pro Link to track and log fuel pressure readings from my Glowshift fuel pressure sender.

The formula above works. I got data from Glowshift showing voltages and their corresponding pressure readings.

When I do a log with VCM Scanning it shows and records the actual voltage so it's reading the sender but it's not transforming the data to PSI.

I've created the channel, I've gone to transform but my formula is not available under User Defined.

I've tried using a formula from an AEM transform provided by HPTuners but the formula doesn't work for my application.

How do I apply my user defined math expression in my transform for my channel?

KYWes · Apr 15, 2021

I've gotten answers to my questions working with Tech Support at HPTuner.

First my assumption was wrong regarding using a Math Parameter on a Transform. A formula created in Math Parameters is not for use on a Channel Transform. Formulas created with the Math Parameter Manager are for use with the Graph, Chart, and Gauge functions only.

Secondly, my formula was good but I did not have my parentheses or brackets placed correctly. Once I straightened these out my formula worked like it was supposed to.

My situation:
I have a Glow Shift Fuel Pressure sensor/gauge system. The Glow Shift provides voltages from 0 to approximately 3 volts. In contrast AEM and others use a 0-5v scale. Using data provided by Glow Shift I created a formula to convert the voltage supplied by the sender to a number representing the fuel system PSI. The formula is ([30012.10]-O)/M

[30012.10] is a code in HPTuners that represents the volts provided on the Blue Channel of the MPVI2 Pro Link connector.
O represents the offset
M represents the multiplier
(I can also tweak the variables of the formula to ensure what is logged in HPTuner matches what the gauge reads.)

Using a data chart from Glow Shift for their sender, I calculated the Offset at .5v and the multiplier as .02758. Thus O and M are constants in the formula. The result is a number corresponding to the PSI of the Fuel Pressure on my 1995 Z28 Camaro.

Now that I've got the process working, I can record the fuel pressure of my car under driving conditions. Under normal driving this is pretty useless data though it will show if the fuel pressure is out of spec.

My main purpose for this effort is to view and log the fuel pressure under WOT acceleration on high rpm conditions. This should help me know if my fuel pump and fuel system is providing the necessary fuel pressure for maximum power.

Note that HPTuner has formulas for other manufacturers, namely AEM, so this was only necessary because I had a Glow Shift Fuel Pressure gauge. The Glow Shift gauge kit is good quality and less expensive

regulars520 · Nov 5, 2021

I have the same gauge and I am also trying to log my fuel pressure. Did you get this to actually log or just display on the gauge in HP Tuners?

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