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Senior Member
1,091 Posts
Discussion Starter #1 (Edited)
Recently picked up a DashDAQ XL by Drew Technologies from tunertools. This thread will serve as an introduction to the device as well as news and related things I can do it to help with getting info out of our cars.

It's a linux-based programmable OBDII/CANBUS device than can monitor/log various engine sensors and do calculations to those signals on the fly. It can read and clear check engine lights. It also features connectivity to aftermarket sensors as well as GPS support. It is definitely not cheap, in comparison to other available OBDII readers but the constant support, updates and programmability are what give sense to the cost. The 2nd gen Mazdaspeed3 has an immensely revamped ECU rendering earlier OBDII readers unhelpful in monitoring vitals necessary for tuning.

Current readable signal list: (to be expanded)

DashDAQ Available Signals Report

Time: Mon Jun 21 20:07:41 2010
Firmware Version: DashGUI-2.1.2-1949

Device: a-Generic OBD2 Version:2.1.2-1949
   9998   "Latency"   "OBD Latency"   "ms"   0
   9999   "Updates"   "OBD Update Rate"   "Hz"   0
   9996   "NET"   "OBD Network Type"   ""   0
   33   "LOAD_ABS"   "Absolute Load Value"   "%"   0
   14   "TP"   "Absolute Throttle #1 position"   "%"   0
   37   "TP_B"   "Absolute Throttle Position B"   "%"   0
   39   "APP_D"   "Accelerator Pedal Position D"   "%"   0
   40   "APP_E"   "Accelerator Pedal Position E"   "%"   0
   13   "MAF"   "Air Flow Rate from MAF"   "g/s"   0
   36   "AAT"   "Ambient air temperature"   "°C"   0
   27   "BARO"   "Barometric Pressure"   "PSI"   0
   1   "LOAD"   "Calculated Load Value"   "%"   0
   28   "CATEMP11"   "Catalyst Temperature Bank 1, Sensor 1"   "°F"   0
   20   "EGR_PCT"   "Commanded EGR"   "%"   0
   34   "EQ_RAT"   "Commanded Equivalence Ratio"   ""   0
   22   "EVAP_PCT"   "Commanded Evaporative Purge"   "%"   0
   42   "TAC_PCT"   "Commanded Throttle Actuator Control"   "%"   0
   32   "VOLTS"   "Control module voltage"   "V"   0
   17   "MIL_DIST"   "Distance Travelled While MIL is Activated"   "miles"   0
   25   "CLR_DIST"   "Distance since DTCs cleared"   "miles"   0
   2   "ECT"   "Engine Coolant Temperature"   "°F"   0
   9   "RPM"   "Engine RPM"   "RPM"   0
   26   "EVAP_VP"   "Evap System Vapor Pressure"   "PSI"   0
   23   "FLI"   "Fuel Level"   "%"   0
   19   "FRP"   "Fuel Rail Pressure"   "PSI"   0
   300   "FUELSYS1"   "Fuel System 1 Status"   ""   0
   301   "FUELSYS2"   "Fuel System 2 Status"   ""   0
   4   "LTFT1"   "Fuel Trim Bank 1 - Long Term"   "%"   0
   3   "STFT1"   "Fuel Trim Bank 1 - Short Term"   "%"   0
   11   "SPARKADV"   "Ignition Timing Advance (#1)"   "°TDC"   0
   12   "IAT"   "Intake Air Temperature"   "°F"   0
   8   "MAP"   "Intake Manifold Absolute Pressure"   "PSI"   0
   200   "MIL"   "Malfunction Indicator Lamp (MIL) Status (On/Off)"   ""   0
   24   "WARM_UPS"   "Number of warm-ups since DTCs cleared"   ""   0
   132   "O2B1S1wr"   "O2 Bank 1 Sensor 1 Current (wide)"   "mA"   0
   180   "O2B1S1w"   "O2 Bank 1 Sensor 1 Lambda (wide)"   ""   0
   103   "O2B1S2"   "O2 Bank 1 Sensor 2 Fuel Trim"   "%"   0
   102   "O2B1S2_V"   "O2 Bank 1 Sensor 2 Voltage"   "V"   0
   303   "OBDSUP"   "OBD Requirements"   ""   0
   35   "TP_R"   "Relative Throttle Position"   "%"   0
   16   "RUNTM"   "Time Since Engine Start"   "sec"   0
   10   "Speed"   "Vehicle Speed"   "MPH"   0
Currently, I'm interested in monitoring the following signals (this list will grow):
[x] Intake Air Temperature
[ ] Boost Air Temperature (this signal is not documented yet)
[x] Air/Fuel Ratio
[ ] Engine Knock (this signal is not documented yet)
[x] Engine Coolant Temp (ECT)
[x] Short Term Fuel Trim
[x] Long Term Fuel Trim
[x] Fuel Rail Pressure

Air/Fuel Ratio is monitored from an oxygen sensor in the downpipe. The signal is a value of lambda, and ranges from 0 to 2. The normal Air/Fuel ratio is 14.7 : 1, so to make the value meaningful in terms of display we can apply a calculation to the signal so it'll always display Lambda x 14.7.

So, you'd go into Device Manager and add a Rescale Signal Calculator. In Parameters, you'd find the Rescale Signal Calculator and select the following:

Input Signal: O2 Bank 1 Sensor 1 Lambda (wide) = Generic OBD2.O2B1S1w
Multiplier Signal: Rescale Signal Calculator.m (Constant Multiplier)
Multiplier Sign (1 or -1): 1
Constant Multiplier: 14.7
Offset Signal: Rescale Signal Calculator.b (Constant Offset)
Offset Sign (1 or -1): 1
Constant Offset: 0
Name: AFR
Precision: 3

Boost Pressure is calculated by subtracting the Intake Manifold Absolute Pressure and the Barometric Pressure, so you'd create a Rescale Signal Calculator Parameter and set the following options:

Boost Rescale Signal Calculator:

Input Signal: Intake Manifold Absolute Pressure = Generic OBD2.MAP
Multipler Signal: Rescale Signal Calculator.m (Constant Multiplier)
Multiplier Sign: 1
Constant Multiplier: 1
Offset Signal: Barometric Pressure = Generic OBD2.BARO
Offset Sign: -1
Constant Offset: 0
Name: Boost
Units: PSI
Precision: 1

Senior Member
1,091 Posts
Discussion Starter #3 (Edited)
Some things I've observed:

Engine load at idle: 20%
Engine load in gear, going downhill, no gas: 3-5%
Engine load in gear, going downhill and maintaining speed: 5-7%
Engine load caused by air conditioning turned on (regardless of fan speed): 3-6% additional
Engine load is largely affected by road incline/decline, as well as rate of acceleration, gear, rpm

Fuel rail pressure at idle: 400+- PSI
Fuel rail pressure will jump to 1200 PSI almost as soon as you touch the gas
Moderate pressure on the pedal will bring it up to 1600 PSI. I believe the highest I've seen is just under 1700.

Long term fuel trims range from 5-9% (only performance mod is short ram intake/turbo inlet pipe)
Short term jumps wildly between +- 5%

Intake air temperature will climb rapidly at standstill/slow speed. Once moving over 40mph, intake and ambient deviate by 2-5 degrees. At over 70 mph, intake and ambient become the same. Not sure what boost air temps are unfortunately. (intake air gets heated by the turbo and cooled by the intercooler, best possible estimate from first gen is anywhere from 30-50 degrees warmer than intake)

I have my drive up from LA-SF data logged.

Recorded boost, intake air, ambient air, fuel level, MAF air flow, AFR, LTFT, STFT, and some other parameters.

On a pull from 30 to 100mph, boost spiked to 17.69 PSI

Senior Member
1,091 Posts
Discussion Starter #5
Well, intake air temperature should not go below ambient air right? How could it? When I was cruising back on highway 5, it was 106 outside.

Wanna know what my intake air temp was at 75mph?

106 as well.

The point being that a cold air intake does not snag as much engine bay heat when idling or going slowly, but this car does not like to be driven slowly. It likes to go fast, it likes to go faster when already going fast, and besides, if you're looking to not blow the engine early you're ideally not stepping on it til you're past 3500 rpm, and probably 3rd gear for that matter so you're not boost limited to 7 PSI.

How fast is 3500 rpm in 3rd gear? About 40mph. What's your intake temp? Almost ambient.

What's the gain of cold air vs short ram in this scenario?

Not much.

Senior Member
1,091 Posts
Discussion Starter #6 (Edited)
A user asked for some pics of how I have mine setup:

Driver view- DashDAQ on the left, iPhone on the right

First set of gauges:

Air/Fuel Ratio, RPM, Fuel Rail Pressure, Mass Airflow, Short Term Fuel Trim, Long Term Fuel Trim, Speed, Load %

Second set of gauges:

Boost, Air/Fuel Ratio, Short Term Fuel Trim, Intake Air Temp, Fuel Rail Pressure, Long Term Fuel Trim, Ambient Air Temp, Engine Coolant Temp, Load %

Yes, there are redundant gauges. I usually watch the second one as my car is getting warmed up, and switch back to the first set while monitoring a pull. This was after my car was sitting on and in my driveway for about two minutes, and as expected, the intake air temp will climb as the car is not moving.

114 Posts

WOW! Not only am I thoroughly impressed with what you have installed and where, but your detailed scientific methodology is spot on!

About the device. Yes it is expensive, but it offers so much for the price. Customizable (functional and beautiful) interface, update capabilities, Linux platform and so much more! What is the device refresh rate like? I imagine it would be pretty quick, with the MS3 being CAN bus.


THANK YOU for adding to the proof that cold air intakes DO NOT add much advantage in most situations on turbocharged engines. I would think that an inlet path to the turbo should be as short and restriction free as possible (you know, like those race cars). Since the air is gonna get compressed (and thus, heated) anyway, the real important issue is how much heat can be dissipated before it gets to the throttle body/manifold. I have a friend with a 2007 WRX who would NOT STOP arguing with me that his cold air intake did something significant to lower overall intake temps. I kept saying: "Not with that heat-soaked TMIC it's not"

Senior Member
1,091 Posts
Discussion Starter #9

What is the device refresh rate like? I imagine it would be pretty quick, with the MS3 being CAN bus.
According to my log files, I see about 12 updates per second. It's logging around 15 parameters. I've read the DD can handle up to 200 per second.

Think these numbers are applicable to the 2.5 liter engine?
I could speculate, but I'd like to test it out to be sure since the intake system on a N/A has less fluctuation of air temperature flying before the intake manifold than in a turbo setup.

People really need to understand that the greatest performance gain comes from removing the restrictive stock airbox. How you choose to filter, meter and feed air in after removing the restrictive airbox is up to you (SRI vs CAI), and is of a lesser consequence. Other cars come with amazing stock airboxes to which switching to an aftermarket intake yields little to no gains.
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