Read this guide made by Eric, Torqued Performance tuning, he’s a renowned eTuner based in the USA.
https://www.wrxforums.com/threads/erics ... logs.7623/
For AccessPort users: https://cobbtuning.atlassian.net/wiki/s ... To+Datalog And: https://www.youtube.com/watch?v=uIo6tqFtA3w
If you’re interested in how to graph and analyse datalogs, here’s a full breakdown of the process for an my07 GT that is returning “take action” results in Learning View: http://forum.liberty-asn.au/viewtopic.php?f=18&t=37404
Whilst I’m not a tuner, I consult regularly on state of tune and DTC issues, worldwide, I have an extensive archive of known good and bad logs, and extensive contacts in the enthusiast community. I’m happy to help out with your logs but only by forum or group posts, please don’t PM.
Note: if you have any obdii plug &/or app combo, but *no logging* and need a quick diagnostic check, make a note of these on board diagnostic parameter values :
During warm idle:
RPM
AFR
Intake manifold vacuum
Fuel correction
Fuel learning
Engine coolant temperature
Is idle stable, year, model, engine, transmission?
Eg for an h4 turbo, the warm idle stats are roughly:
RPM: 700-800
AFR: 14.7
Intake manifold vacuum: -10psi/-20in/hg
Fuel correction: ideally zero or within +/-5%
Fuel learning: within +/-5%
Engine coolant temperature: 86-94C
Is idle stable: eg within 700-800rpm.
If not, get back with your figures as they’re a huge clue to your current state of tune, in closed loop.
Ideally you already have a Cobb AccessPort or OS open source SSM obdii logging interface, eg Vag-com, OBDlink LX or MX or Tactrix Openport, if not:
For open source, this is as affordable as buying a $15 clear blue case VAG-COM KKL 409.1 usb obdii plug.
This works with a PC with FreeSSM (live data no logging), RomRaider Logger and Learning View; and on Android with BtSSM with the appropriate OTG female usbA to your phone usb adapter.
Logging off boost is fine, unless you’re diagnosing load or boost related issues, on condition that you’ve already properly confirmed no boost or lcv leaks eg using this guide:
viewtopic.php?f=6&t=36513
20 minutes cold start to warm log, a/c off
See below for recommended parameters.
Its possible to get a good idea of basic engine health from a cold to warm idle, no haptic input, no a/c.
Since it’s a repeatable test it’s a good baseline to track any improvement after repairs.
If the engine has had recent significant maintenance or repair, reset the ecu prior to logging warm to hot, no haptic input, plus a following off boost fuel learning run.
20 minutes plus, street and freeway driving,
long part-throttle & vacuum pulls… and at least a few minutes of WARM idle
![Smile :)](./images/smilies/icon_smile.gif)
For more detail on the intent behind making diagnostic datalogs see this reply: viewtopic.php?f=6&t=36932&p=459553#p459553
Being stabby with the throttle will fill the datalog with transient data, so limit abrupt throttle to less than half of the log.
Warm idle and steady freeway cruise are useful for analysing closed loop operation, so include a few minutes or way more.
If there’s a drivability fault or issue, try to capture that in the datalogs.
Only if safe for your engine of course, if it can only idle, log idle, again if safe to do so.
The more data the better, by this I mean the length in time of the log.
After ecu reset, some advise to “learn the ecu in” with an off boost drive with some traffic & freeway cruise.
An ecu reset and idle relearn (DBW throttle) might be necessary after maintenance, eg the process can cure rev hang after UEC treatment.
Idle relearn: turn off all accessories, open drivers window, reset ecu (scan tool or pull battery negative temporarily and press brake to drain the electrical system including ecu fuel and knock learning), start the engine via drivers window, let the engine idle for 15minutes plus until fully warmed up.
Ideally you’ll datalog this process and the subsequent ecu relearn drive.
Sharing logs!
*share* a *link* to the csv file using google drive, wetransfer, dropbox etc.
The idea with sharing logs is to upload the csv file from your pc, laptop etc, to the cloud, then share a link to the file in the cloud, aka online data storage.
Its also possible to use the Datazap app, again upload the log csv to the app, share from the app.
Or from the Wetransfer website: send the csv file to your own email, share the download link from the upload confirmation email.
Learning parameters are generally FBCK, FLKC, Fuel Correction (STFT/short term fuel trims) and Fuel Learning (LTFT/long term fuel trim), Knock Sum.
Other essentials parameters for logging are referred to as tuning parameters, but generally vehicle speed, petrol afr, rpm, tps, manifold relative pressure and engine coolant are essential for log clarity.
How to log AP:
https://www.google.com.au/search?q=how+ ... ent=safari
Cobb AP parameter list:
https://cobbtuning.atlassian.net/wiki/s ... nitor+List
When logging, use tuning parameters:
Less parameters = better log resolution, eg don’t use every available parameter, use the parameters in these lists as a starting point and add or remove parameters as required, eg per cylinder misfires/roughness and avcs for a misfire fault, fuel pump duty cycle for a fuelling issue (if stock FPCM), rear O2 parameters for unexpected fuel trims on cars w/o rear O2 delete, etc.
Logging Parameters for H4DOTC:
From Torqued Performance:
A/F Correction #1(%)
A/F Learning #1(%)
A/F Sensor #1(AFR)
Coolant Temperature (C)
Engine Load (g/rev)
Engine Speed
Feedback Knock Correction
Fine Learning Knock Correction
IAM/DAM
Ignition Total Timing
Injector Duty Cycle
Intake Air Temperature
Knock Sum
Manifold Absolute Pressure (PSI)
Manifold Relative Pressure(corrected)(PSI)
Mass Airflow (g/s)
Mass Airflow Sensor Voltage
Throttle Opening Angle(%)
Vehicle Speed (mph)
Optional (but mandatory for health check):
VVT angles (AVCS VVT intake and where applicable, exhaust, Left and Right)
WDC
VVT specific parameters:
Engine Speed
Vehicle Speed (mph) (kph if not logging for a USA based tuner)
VVT angles (L&R)
OCV duty (L&R)
OCV current (L&R)
Logging parameters for H6DO:
From XRT
32bit ECU - H6 3.0R
A/F Correction #1 (%)
A/F Correction #2 (%)
A/F Learning #1 (%)
A/F Learning #2 (%)
A/F Sensor #1 (AFR)
A/F Sensor #2 (AFR)
VVL Lift Mode (raw ecu value) ((aka ALVS))
Accelerator Pedal Angle (%)
Coolant Temperature (C)
Engine Load (Calculated) (g/rev)
Engine Speed (rpm)
Fine Learning Knock Correction (degrees)
IAM (multiplier)
Ignition Total Timing (degrees)
Injector Duty Cycle (%)
Intake Air Temperature (C)
Intake VVT Advance Angle Left (degrees)
Intake VVT Advance Angle Right (degrees)
Learned Ignition Timing (degrees)
Manifold Absolute Pressure (psi)
Mass Airflow (g/s)
Mass Airflow Sensor Voltage (V)
Oil Temperature (C)
Throttle Opening Angle (%)
Vehicle Speed (km/h)
Parameters for Cobb AP (see next posts) Btssm will have similar but different names, if in doubt just google it
![Wink ;)](./images/smilies/icon_wink.gif)
Stay safe and no hero mode!
Here’s an in depth video explaining some of the concepts related to data logging, specifically the role of fuel trims.
https://m.youtube.com/watch?v=FP3bu3UBz5k
And misfire diagnostics:
https://m.youtube.com/watch?v=4iYBzP3kUjk
![Wink ;)](./images/smilies/icon_wink.gif)