Datalog Analog Inputs with SCT X4 and LiveLink. HELP!

[Midlife Crises]

Recently installed an AEM a/f meter that seems to function just fine but trying to get numbers I recognize on a datalog is driving me nuts. The meter has a 1-5 volt output that when connected to the FireWire as instructed and plugged into an X4 I can view and log the voltage. From the menu in the X4 I can select a formula to change the readout from voltage to A/F. Problem is it is not the correct formula and I can’t figure out how to alter or add a new formula to the X4. Do any of the tuners here know how to accomplish this?
Moving on to LiveLink. When I connect to LiveLink for a log session I can bring up the analog inputs along with other PIDs and record them. Again, the two analog inputs (channel 7 and 8) display only voltage. I have found the formulas in “Tools” and tried to apply them but it does not change the voltage reading to A/F as I believe it should. What am I doing wrong?
Any assistance getting the 1 to 5 volt output to record as air/fuel ratio is greatly appreciated.

 

[DieHarder]

Not a tuner but I believe I have the same software setup as you. Using an AEM 30-4900/X-4 and Lito did my tuning.

According the manual (attached) on pg. 17 use the following AFR Output Transfer Function formula:

AFR (Gas) = (2.375 * Volts) + 7.3125
That should yield outputs between 0 - 5v.

I believe in my setup it's named: Analog In 8 - Orange Firewire

 

[DieHarder]

I'd be happy to send you one of my log's or tell me where to look and I'll give it a shot. According to my read of the manual if the output is between 0 - 5v it's working properly. You may have to interpret the AFR using the chart. All I get on my logs is a varying voltage between 0 - 5v that averages around 2.8 which is (according to the chart) close to what I see on my gauge (14.4 - 14.6).

 

[Midlife Crises]

All I get on my logs is a varying voltage between 0 - 5v

It appears we are set up the same. Analog 8-orange FireWire and that is the formula I entered into LiveLink. I can see and log the voltage just as you mention and have the conversion chart in the AEM instructions. What I am trying to achieve is to get LiveLink to display and record A/F rather than Voltage. I also have Analog 7 wired to a boost gauge with its own formula and it does the same thing.

 

[DieHarder]

It appears we are set up the same. Analog 8-orange FireWire and that is the formula I entered into LiveLink. I can see and log the voltage just as you mention and have the conversion chart in the AEM instructions. What I am trying to achieve is to get LiveLink to display and record A/F rather than Voltage. I also have Analog 7 wired to a boost gauge with its own formula and it does the same thing.

A quick search of the web reveals a couple of results that may help you. The first appears fairly straight forward. The second one not so much but may provide some insights of value none the less.

https://www.corral.net/threads/need-help-with-datalog-equation.1032122/

https://ecutek.zendesk.com/hc/en-gb...Re-scaling-the-Factory-Air-Fuel-Ratio-Sensor-

There are some more reference links out there as well. If the first datalog equation doesn't work I'd recommend contacting AEM to see what they have to say.

 

[DieHarder]

So, it appears the preset equation to convert voltage outputs to A/F for the AEM wideband is: (v*2)+10 which would square for the most part with what I'm logging for voltages. Kinda close but not perfect.
Min: 0.816
Max: 4.349
Avg: 2.818

Inserting into the formula yields:
Min: (0.816 x 2) +10 = (1.632) +10 = 11.632 (Max throttle)
Max: (4.349 x 2) + 10 = (8.698) +10 = 18.698 (Pretty much KO/EO) Gauge reads 18.0
Avg: (2.818 x 2) +10 = (5.636) + 10 = 15.636 (My actual indicated readings on the gauge are 14.4 - 14.7 so not sure which is correct. Other logs indicate the same raw voltages. I suppose you could write in a correction factor of -0.5v volts which would make the logs closer to what the gauge reads. Might have to experiment with the formula somewhat. A quick stab might be ((v-0.5)*2) + 10

 

[Midlife Crises]

OK. I was messing around with LiveLink this afternoon and was able to get voltage numbers to change as I altered the formulas so I should be able to get it to work as intended. Just looking at the raw voltage and comparing it to the AEM chart it does not match up. Idling my gauge reads around 14.6 to 15.0 and the voltage logs about 4.6. When I apply the formula (2.3750*v)+7.3125 that came with the meter I record numbers in the 18 range. This does match up with the voltage of 4.6. I will look more closely at my power supply and grounds as I have read they can be an issue.

 

[DieHarder]

Agreed. Go with AEM's transfer function. However, that voltage (4.6) seems high. Was the engine warm?

When running you should be seeing voltages in the ranges on the chart. For idling (once warm) if you're gauge is reading 14.6 to 15.0 the voltage recorded should be around 3.1/3.3 v to come up those A/F's according to the math. When I log mine I'm seeing voltages in the ranges below.

Applying the math. AFR = (2.375*v) + 7.3125

Min: 0.816; A/F = 9.2505
Max: 4.349; A/F = 17.64
Avg: 2.818; A/F = 14.00

Which is close to what I'm seeing on my gauge (~14.5); though not perfect.

For grounds I separated mine according to recommendations I read when I was researching installation. I think what's important there is to ensure the gauge connections are at battery/frame ground potential. The best frame/battery ground I know of is on the driver's side strut tower.

 

[Midlife Crises]

Exactly what I am thinking. Showing 14-15 on the gauge I should have voltage around 3. If I get to the shop today I will verify solid connections through the FireWire and run battery direct +&- gauge connections for testing. I do have this gauge sharing power with other gauges, maybe it needs to be isolated.

 

[DieHarder]

You have a shop? Now, I'm jealous. Seriously, just wish I had a 3-car garage for projects and such. I actually had a chance to buy a wrecked 08 GT500 that I wanted to transfer the engine/drive train over to my 06. Ran and everything...but passed because I didn't have the room (and the junkyard wanted $13.5K but I probably could have talked him down a bit). In hindsight kinda wish I'd done it.

 

[Midlife Crises]

Shop. An enclosed working area is mandatory here. Temp is in the 30s now and snow fell a couple days ago. I’m fortunate enough to have a detached, heated three bay garage for a shop. House also has a 1 1/2 bay garage attached. I could use 2 more bays easily but damn heating is expensive.

 

[Rick Simons]

IIRC LiveLink will do the V/AFR scaling for you once you tell it what hardware you're using.

 

[Midlife Crises]

Success! I was able to get the AEM A/F gauge and the LiveWire data log to match up close enough to trust. First I connected the A/F meter directly to the battery. “With a fuse of coarse”. Temporarily connected the FireWire with wire nuts and plugged it into the X4. The X4 does not contain the correct formula for the current AEM meter so I selected V for the readout. Letting it idle, the gauge reads 14-15 a/f and the X4 shows 3 volts or a little more. Now hooking up the laptop with LiveLink and the X4 set to volts I get a matching volts reading on the datalog. Entering the correct formula into LiveLink converts the volt reading to A/F and matches the gauge reading. Awesome. I suspect the same setup will work for the Boost gauge as well. A clean voltage supply, the X4 set to volts and the formula applied in LiveLink.

 

[Midlife Crises]

You have a shop? Now, I'm jealous. Seriously, just wish I had a 3-car garage for projects and such. I actually had a chance to buy a wrecked 08 GT500 that I wanted to transfer the engine/drive train over to my 06. Ran and everything...but passed because I didn't have the room (and the junkyard wanted $13.5K but I probably could have talked him down a bit). In hindsight kinda wish I'd done it.

Remember I said a shop is mandatory here. Happy October.