VAG-COM

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VAG-COM

• TDI Fest 2002
• TDI-Specific Procedures

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Summary

• Introduction
• Basic operations
• Checking the air system
• Setting the injection timing
• Special adaptations
• Performance Measurement
• More Information

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Introduction what isVAG-COM?

• Emulates the dealers VAG-1551 and VAG-1552 tool
• Uses Windows-based PC (100 MHz recommended)
• Used by enthusiasts, general repair ships,
  transmission shops, locksmiths, dealerships
• Uses VAG protocol (separate from OBD-II)

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Basic Operations

• Read/Clear/Print Fault Codes (DTCs)
• Diagnose MIL (Check Engine Light - CEL)
• Monitor/Log/Print Measuring Blocks for various
  running parameters
• Recode convenience items (power locks, radio,
  etc.)

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Note

• The following advanced operations are intended
  for an A4 TDI (ALH engine). Expect some
  variations if you have an A3/B4 car (A3 Jetta,
  Passat)

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Air system part I MAF

• Go into Engine measuring block 003
• Start Logging data
• In a high gear (4th/5th), give full throttle from
  1500-2000 rpm up to 3500-4000rpm.
• Find and Open the Log file in Windows Explorer
• Graph MAF specified/actual/rpm -vs- time in Excel

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Checking the MAF - continued

• The MAF is OK if the actual value is more than
  850-900 mg/h at 3000 rpm.

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Air system part II Turbo

• Go to Engine Measuring Block 011
• Start Logging the data
• In a high gear (4th/5th) give full throttle from
  1500-2000 rpm to 3500-4000 rpm
• Find and Open the Log file in Windows Explorer
• In Excel graph actual/requested boost/rpm vs time

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Turbo - continued

• On a stock vehicle, one should see a spike at 2.1
  bar quickly regulated at 1.9 through the whole
  rpm range

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Setting the injection timing

• Engine has to be warm (coolant above 85ºC)
• Go to Engine Measuring Block 000
• Switch to Basic Settings
• Take note of the values in fields 2 (timing) and
  9 (fuel temp)
• Report in the following graph (also in the
  Bentley manual)

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Setting timing-continued

• Specification is between the blue and red lines
• To slightly advance timing, you need to be in the
  upper portion of the graph. Setting is done
  mechanically, slightly rotating the pump sprocket
  once its three screws have been loosened.
• It is strongly discouraged to set your timing
  outside of the specification!
• Graph is available at http//pics.tdiclub.com/memb
  ers/ericmaurier/timing.xls

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Special adaptations Login code

• To perform the following adaptations (except
  idle) you need to use the Login function. Enter
  12233 as a Login code.
• Misuse of some of the adaptations can lead to
  engine failure. This is done at your own risk!
• Note that the EGR setting is for off-road use
  only...

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Channel 1 injected quantity

• Check the injected quantity at idle, engine warm
  and all power consuming devices turned off.
  Specification is 2.5 to 9 mg/h.
• To change the amount of injected fuel perceived
  by the ECU, go to adaptation channel 1.
• If you have driveability problems, you may want
  to increase it to 3-4 mg/h.
• For slightly improved throttle response, you may
  try to decrease the value.

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Channel 2 idle speed

• No login required
• To increase idle speed, increase the value and
  vice-versa

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Channel 3 EGR

• To decrease the EGR rate, increase the number to
  the highest possible value (typically 33768)
• This will prevent/slow down the intake manifold
  clogging problem and reduce smoke
• Though the MAF at idle is still within
  specifications (370 mg/h) do not use this
  adaptation on the road -)

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Channel 4 start of injection

• This channel commands the start of injection over
  the whole operating range of the engine,
  including at full load. Advanced timing there may
  lead to severe damage to the engine because of
  the increased combustion pressure.
• It is in no way a substitution for the mechanical
  pump setting seen previously
• In a nutshell dont mess with it!

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Channel 5 starting conditions

• Though undocumented, this channel effects the
  injected quantity the ECU allows when cranking
• You may want to experiment with it as a temporary
  fix for bad-start problems

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Performance Measurement

• Butt Dyno

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More Info

• Mk IV Lock/Unlock Horn/Flash
• Select46 - Cent. Conv. (35 - Cent. Locking
  for manual window cars)Adaptation - 10Channel
  (03..08)Adaptation Value (1 on, 0
  off)SaveChannel 03 Auto LockChannel 04 Auto
  UnlockChannel 05 Unlock, horn soundsChannel 06
  Lock, horn soundsChannel 07 Unlock, turn signals
  flashChannel 08 Lock, turn signals flash
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