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Datalogging AEM Digital Boost Gauge

4K views 4 replies 3 participants last post by  NJSVTGUY 
#1 ·
Hi Guys,

I was just wondering if anyone has had any success datalogging the analog output from an AEM Digital Boost Gauge (30-4406).

I have wired up my Xcal 3 to datalog the analog output, 0-5 volts that the gauge supplies and attempted to apply this equation to the raw voltage signal:

*Equation*: PSIA=12.5*(volts)-6.25* scale: .5v-4.5v = 0-50psia

which should then provide the boost.

I'm running a JRSC which sees 10 psi at redline. The boost level is indicated on the gauge however applying the formula to the analog output I don't get an accurate boost figure to datalog.

Can anyone advice an amendment to make to the above formula or possible reason the analog output may not be providing an accurate signal for datalog?

Thanks for the help.

Mike
 
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#3 ·
Hi Tom,

Yes I have tried that.

The figures I am getting back don't match what is indicated on the boost gauge.

I will post up some figures from the datalog later, however if I start the datalog with accessories on but prior to turning the engine on, the datalog for the AEM boost gauge (with the equation applied to the RAW 0-5 v) returns a value of around 13. Obviously with the car off this value should be 0.

I will re-check the wiring tonight however I don't see this being the problem. I will also complete a datalog of all analog inputs 1 to 4 to see if it is somehow being picked up on one of the other analog inputs. I don't think this will resolve my problem either as the analog input 2 is reading between 0.5 and 4.5 volts as AEM advise the analog output fror their boost gauge should.

I've had no issues datalogging the AEM wideband by applying the formula through livelink.

Thanks,

Mike
 
#4 ·
Hey All,

Is anyone aware if the analog signal provided by the AEM Digital Boost Gauge provides an absolute pressure. ie. atmospheric pressure plus the pressure created by the supercharger/turbo etc?

If this is correct I am at or around sea level so I have an approximate atmospheric pressure of 14.7 psi.

If this is the case I would need to modify the formula applied to the raw 0-5 volts from the AEM boost gauge to be "[(12.5*v)-6.25]-14.7". Anyhow applying this formula the boost levels I am datalogging appear significantly more accurate.

Can anyone confirm if this correction for atmospheric pressure is required?

Thanks,

Mike
 
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