Analog inputs - SRT Forums

forcefedjunkie · 07-20-2006, 01:06 PM

We have found these to be so useful in the past couple months since we implemented them, that I thought I'd pass on some tips concerning their use as well as applications we've used. For those not familiar with our gauges, they come standard with two 0-5v analog inputs which go to a 10 bit A/D converter, and allow the user to enter a linear conversion so that the correct units can be displayed rather than raw voltage.

Currently our SRT-4 has an AEM wideband connected to the analog 1 input, and a GM 3 bar MAP (you could use a Chrysler just as easily) to analog input #2. The wide band came from AEM with its analog output set for 0-5v = 10-20 A/F ratio, so I entered the equation V(oltage) * 2 + 10 through the menu. The menu wants to see this equation as a slope (2) and intercept (10). So "2" and "10" are entered when prompted. This is a very quick and simple step which is further described on our manual.

Since I'm using a MAP clamp, the "boost" (MAP sensor) reading on the gauge gets "clamped" when this device kicks in. This is great in one regard, I know what the MAP clamp is set at, and can accurately adjust it. However, I did not know what the true level of boost was above the clamped level. For this reason I added the 3 bar MAP sensor, which I tee'd into the vacuum line by the throttle body. Now I can accurately read boost up to 29 psi. I calculated the slope to be 9, and the intercept (also known as zero offset) to be -14.4 for my location. Atmospheric pressure changes will effect this reading. A change in atmospheric pressure of 0.2 psi will throw off the reading by 0.2 psi. Changes of more than +/- 0.2 psi are not that common. Worst case this pressure can change by .4 psi. For me, that is acceptable, knowing my boost level to +/- 0.2 psi is good enough. However, if I were to travel to a location with a significant altitude change, all I'd have to do is take a few seconds to enter a new intercept (offset) to correct for this. There is an easy way to determine the correct intercept. Turn the ignition on with motor off, and look at the gauge's reading. If it's not zero, note the value, and adjust the intercept by the same amount. For example, you have entered an intercept of -14.4, and the gauge reads +0.2 psi with the engine off. You need to correct the intercept to eliminate this, so change it to -14.6. Now you will see "0" with engine off. This is also how to correct for zero shifts in the sensor itself. These sensors, whether they be a MAP, oil pressure, or whatever, are not extremely precise units. They are very good, but not perfect. For example, on another test vehicle we found our aftermarket MAP to read about 0.4 psi high, so we used the intercept entry to eliminate this error. Slope is virtually never an issue. Bottom line is the accuracy of your readings are as good as the conversion you enter. You can eliminate sensor errors, since you are entering the conversion.

We've also had fuel pressure and oil pressure senders connected to the analog inputs. These have especially easy converions since they usually have "0" for the intercept. A 100 psi fuel pressure sender for example would have a conversion of slope = 20, and intercept = 0, or voltage*20 + 0 = psi. Again, you may find that these senders have a slight offset from the factory, which may be very small, 1-2 psi, so a value other than zero may be needed for the intercept if high accuracy is required.

In the near future you will also be able to connect EGT sensors to our gauge. Some tuners prefer exhaust temperature readings over A/F ratio, but these very low level, non-linear signals are difficult to log. We'll have a solution soon using these same analog inputs.

I hope this is somewhat informative, and conveys the value and ease of use of these inputs.

Todd

KeyboardCommando · 08-01-2006, 10:39 AM

Thats good to know...especially since I have a wideband gauge I really like but I wouldn't mind getting rid of my fuel press. and oil press. gauges for 2 of your gauges

Sota · 10-02-2006, 09:31 PM

Is it possible to rename the analog items with specific names? Say for example I were going to explicitly use an A/F on Analog 1 and a Oil Pressure on Analog 2? Also could it then display the proper units?

forcefedjunkie · 10-06-2006, 01:01 PM

Quote: Originally Posted by Sota227990

Is it possible to rename the analog items with specific names? Say for example I were going to explicitly use an A/F on Analog 1 and a Oil Pressure on Analog 2? Also could it then display the proper units?

They already do display proper units provided you enter the correct conversion.

Adding an option to allow people to enter their own descriptions would be nice but accomplishing this with two buttons would be very tedious.

We appreciate the suggestion though.

Todd

lyncoo · 03-26-2007, 01:12 PM

can i tap into the wire comming off the dtec to see what my voltage is comming out of it

forcefedjunkie · 03-26-2007, 04:00 PM

Quote: Originally Posted by lyncoo

can i tap into the wire comming off the dtec to see what my voltage is comming out of it

The gauge will read any 0-5v signal. The gauge has a high impedence input so it will not effect the voltage level.

Todd

lyncoo · 03-26-2007, 07:48 PM

Quote: Originally Posted by forcefedjunkie

Quote: Originally Posted by lyncoo

can i tap into the wire comming off the dtec to see what my voltage is comming out of it

The gauge will read any 0-5v signal. The gauge has a high impedence input so it will not effect the voltage level.

Todd

thanks this guage is awsome

KeyboardCommando · 03-26-2007, 07:57 PM

make sure you reconnect the flux capacitor to the gauges #2 input enfibulator dihedral thats solderd together with the controlling dinglearm.

lyncoo · 03-26-2007, 08:06 PM

Quote: Originally Posted by KeyboardCommando

make sure you reconnect the flux capacitor to the gauges #2 input enfibulator dihedral thats solderd together with the controlling dinglearm.

now im lost

KeyboardCommando · 03-28-2007, 11:10 AM

Quote: Originally Posted by lyncoo

Quote: Originally Posted by KeyboardCommando

make sure you reconnect the flux capacitor to the gauges #2 input enfibulator dihedral thats solderd together with the controlling dinglearm.

now im lost

theres a video of an "inside the automatic transmission" .... reaaally old and not serious chrysler training video... its hillarious... okkk...moving on...

ac_srt4 · 04-13-2007, 08:10 PM

hey i have the pro gauge and hooked it up with the aem uego.
the reading on the gauge for afr is SLIGHTLY off compare with uego (about 0.3 or so). not sure if this happens to any of you?

forcefedjunkie · 04-16-2007, 05:07 PM

Quote: Originally Posted by ac_srt4

hey i have the pro gauge and hooked it up with the aem uego.
the reading on the gauge for afr is SLIGHTLY off compare with uego (about 0.3 or so). not sure if this happens to any of you?

Use the intercept value to correct for this. For example, if the Aeroforce gauge reads high by 0.3, then lower the intercept factor in the conversion by 0.3 (if it's 10 lower it to 9.7). You probably used chassis ground for the AEM unit, and the Aeroforce gauge uses signal ground. Chassis ground is not always at the same potential as signal ground and can cause this type of discrepency. This is an easy fix and will correct the reading for the entire range.

Todd

goats srt · 02-13-2008, 07:10 PM

damn i need to try hooking my ergo to the scan gauge what color wire coming off the ergo do i hook up to the scan gauge was it red or blue

forcefedjunkie · 02-15-2008, 11:17 PM

Quote: Originally Posted by goats srt

damn i need to try hooking my ergo to the scan gauge what color wire coming off the ergo do i hook up to the scan gauge was it red or blue

If it's an AEM Uego use the white wire.

Todd

**NoisufnoC** · 02-26-2008, 11:38 AM

bumping this up...

i've got the turboxs tuner pro wideband which has a 0-5v output where i can set the max and min for AFR. assuming I set the min for 10 and the max for 20 like the AEM UEGO i should be able to use the same settings...right?