NefMoto

So, you want to tune your car? Well to do that safely you need to log it.  Dont know how to log? Get ready to read, and read, and read, and learn.  Please keep an open mind, not all of us think the same way.  Be sure to ask questions if anything confuses you, or sounds wrong to you.  ;)


Logging is the concept of gathering data from your cars sensors to see what the ECU sees.   This is needed at the CORE of tuning.  You can not safely tune a car without logging it, IMO.

Logging tools:

• Laptop, your gonna need a newer fast laptop with freespace on the harddrive to store data you are collegting
• Cable and Software,  There are a couple different companies out there that sell software and cables.
• Examples of Software/Cable combos available:  Ross-tech VAG-Com USB interface (http://www.ross-tech.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=VCKII&Category_Code=VAGCOM), ECUx from APR tuning (http://goapr.com/products/ecuexplorer.html)

Logging method:
Different tuners subscribe to different methods of logging and styles of tuning, but the principles are the same. The goal is to get a good running car that has drivability and power. Power goals and how hard you want to push your parts will determine your tuning style, but your logging method should still include the basics.   Depending on what your tuning will determine what exactly you want to log.  For instance if you have your boost dialed in and your tuning the timing, no need to log boost.

Important things to log:

• Boost; Absolute or Relative, preferably both, but at least one.  Units can always be converted later but psi is the easiest and most commonly used.
• MAF:  how much air your engine is eating OM NOM NOM.  preferably in g/s
• Total Timing:  after correction factors, retards and advances, what timing the engine is actually seeing is important.
• Correction Factors (aka Ignition Timing Retard):  How much timing your ecu is pulling to keep your engine from detonating, this is really important.
• Knock Voltage:  It may seem like a crazy amount of knock, but it helps to compare logs
• Throttle and Pedal Angle: good to know your getting 100% when you ask for it.
• Injector Duty Cycle: Extremely necessary when dialing in AFRs (also get a damn wideband cheapass...)

How to log with VAG-com: MJB Motorsports Guide to logging with VAG-Com (http://www.mjbmotorsport.com/datafaq.html) along with some of their Measuring Block Guide (http://www.mjbmotorsport.com/datalog.html)

edit: ill be sure to come back and work on this, time to head in to work :)

Great info, thanks for the post.

You should also log:
-Exhaust Gas Temperature: Lets you know if you are running too lean and generating too much heat.
-Engine Speed: You need this for basic comparisions.
-Intake Air Temperature: Allows you to see how much heat soak you have, incase that ends up increasing knock.
-Specified Boost Pressure: Lets you compare against actual boost pressure to see if the ecu is achieving the pressure it wants.
-Wastegate Duty Cycle: Lets you see if the ecu is actually trying to generate boost or not.

Here is a link to APR Data Logging Guide
 
http://www.goapr.com/support/datalogging.php

Sorry to say that, but the MJB Links are down.. :'(